| 摘要 |
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 water 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.
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