US Patent 9110446 Dye-based time-indicating label

A multilayer time indicator comprises:A. A topsheet,B. An activating layer,C. A timing layer,D. A dye layer, andE. A substrate.In one embodiment the topsheet and activating layer comprise a first or activation section of the indicator while the timing layer, dye layer and substrate comprise a second or base section of the indicator. In one embodiment the activating layer of the first section and the timing layer of the second section are each protected with a release sheet. In one embodiment, the first and second sections of the indicator comprise a kit which can be converted into an active time indicator by removal of the release sheets and joining of the activating layer to the timing layer. In one embodiment the first and second section are joined to one another by a common release sheet or liner which maintains the indicator in an inactive state until the release sheet is removed and the activating layer is joined to the timing layer.