Visually changing paper time indicator employing controllable barrier
AssigneeTemtec, Inc.
InventorsRobert Holt, David J. Haas
Life of this patent
Estimating the term…
Abstract
A time indicator rapidly changes color after a specific time interval. The indicator comprises “back part” that includes a base substrate with a colored dye or colorant deposited on a first surface. A colorant impermeable barrier layer overlays the colorant or colored dye. The indicator further comprises a “front part” that includes a substrate having an adhesive on a first surface thereof. When the back part and front part are put into adhesive contact with each other, the parts coact with each other to cause the colorant impermeable barrier layer to change to a colorant permeable layer to permit the dye to migrate through the layers to cause a color change visible through the front part.
Claims18
A time indicator comprising:
- a back part including a base substrate with a migrating colorant on a first surface;
- a colorant impermeable barrier layer overlaying the migrating colorant to prevent the migration of the colorant therthrough;
- and
- a front part including a substrate with a migration modifier on a first surface, such modifier for modifying the colorant permeability of the barrier;
- wherein, when the back part and the front part are put into contact, the migration modifier coacts with the barrier layer without substantially coacting with the colorant to change the barrier layer to a colorant permeable layer to permit the colorant to migrate through the layer to cause a change that is visually perceptible through the front part.
Dependencies are inferred from the claim text.