Visually changing paper time indicator employing controllable barrier
US6452873B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 14, 2000 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Jun 23, 2020 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41M2205/40
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.