Thermally-activated time-temperature indicator
US4428321A · kind A · utility
47Cited by
21References
9Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Nov 16, 1981 |
| Grant date | Jan 31, 1984 |
| Priority date | — |
| Expiry date | Nov 16, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S252/962
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Device which visually indicates exposure to a temperature within a predetermined range for a predetermined length of time. An opaque microporous sheet has a colored stratum on the back and a transparent fusible coating on the face. The coating is a solid solution of amorphous rubbery polymer in crystallizable solvent which, upon melting, gradually penetrates and transparentizes the microporous layer, rendering the colored stratum visible.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.