Temperature history indicator and its manufacturing method
US4931420A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1987 |
| Grant date | Jun 5, 1990 |
| Priority date | — |
| Expiry date | Apr 29, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24876
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A temperature history indicator and its manufacturing method wherein the indicators are formed as chips, labels, tags or the like and accompanied with those goods or their packings which must be stored at a certain temperature or lower and when their storage temperature rises higher than the certain temperature over a not-permissible time period, this fact can be visibly shown by development or change of color caused by chemical matters in the indicator, characterized in that when temperature rises higher than a certain value, a hydrophobic organic compound enclosed in microcapsules melts and diffuses causing a dye-precursor and a color developer, which are prepared independently of the compound, to be contacted with each other to irreversibly achieve color development or change, that this color development or change system is rendered operative when the temperature rise continues to exceed a permissible time period, and that when the tops of the color development or change systems are coated with a transparent material, the arrangement of a bonding agent is improved neither to break those chemical compositions which cause the color development or change nor to lower their color de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.