Long term rapid color changing time indicator
US7139226B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 2004 |
| Grant date | Nov 21, 2006 |
| Priority date | — |
| Expiry date | Feb 2, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04F1/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A long term rapid color changing time indicator includes a front part and a back part. The front part includes a transparent layer, an opaque layer, a colorant layer, and a neutralizing layer. The colorant layer includes a matrix and a colorant having a non-migratory form that does not migrate in the matrix and having a migratory form that migrates in the matrix. The back part has a reactant. When the front part and the back part are placed in contact, the reactant migrates into the neutralizing layer and a portion of the reactant is depleted by a coreactant. The unreacted reactant migrates into the colorant layer and reacts with the non-migratory form of the colorant converting the non-migratory form to the migratory form such that the migratory form of the colorant migrates through the opaque layer to cause a visual color indication in the transparent layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.