Leach resistant ink for protecting documents from alteration and document protected thereby
US5058925A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 13, 1989 |
| Grant date | Oct 22, 1991 |
| Priority date | — |
| Expiry date | Dec 13, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S428/916
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
An initially colorless, chemically sensitive protective ink which can be readily printed or applied onto a document substrate and which reacts upon contact with an oxidizing agent to form a noticeable color change is provided. The protective ink, when printed onto a document, resists leaching by water for an extended period of time, both before and after contact with oxidizing agents, and provides visible evidence of any attempted tampering. The leach-resistant ink includes a colorless material which becomes colored upon contact with an oxidizing agent and a complexing agent which reacts to form a complex with the colorless material. A fixing agent which promotes insolubilization and fixing of the complex to the document substrate is also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.