Defrost indicator
US4892677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 1984 |
| Grant date | Jan 9, 1990 |
| Priority date | — |
| Expiry date | Dec 19, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S428/913
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A new process is described which is useful for producing novel articles of manufacture useful for monitoring the time-temperature history of perishable items. The process initially involves forming a solution comprised of a diacetylenic monomer and a solvent. The solution is frozen, and the frozen solution having crystalline diacetylenic monomer therein is irradiated to partially polymerize the diacetylenic monomer. Partial polymerization of the crystalline diacetylenic monomer admixed with frozen solvent results in the production of a novel article of manufacture having color. The novel article of manufacture is comprised of frozen solvent, diacetylenic monomer, and colored polydiacetylene. Due to the intensity of the color of the polydiacetylene, the entire article of manufacture appears to be colored. The colored article of manufacture may be attached to various perishables to monitor the shelf life of the perishables. upon exposure to temperatures above a critical temperature, the frozen solvent melts and extracts unreached monomer from the colored polymer, thereby causing a sharp color transition which indicates that the perishable should possibly be discarded.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.