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US 11,524,514 B2Granted
Tamper-proof medium for thermal printing
AssigneeOmya International AG
InventorsRoger Bollstrom, Gilbert Botty, Philipp Hunziker
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Abstract
The present invention relates to method of manufacturing a tamper-proof medium for thermal printing, wherein a liquid treatment composition comprising at least one acid is deposited on a substrate which comprises a thermochromic coating layer comprising at least one halochromic leuco dye.
Claims24
A method of manufacturing a tamper-proof medium for thermal printing, the method comprising the following steps:
- a) providing a substrate, wherein the substrate comprises on at least one side a thermochromic coating layer comprising at least one halochromic leuco dye,
- b) providing a liquid treatment composition comprising at least one acid, and
- c) applying the liquid treatment composition onto at least one region of the thermochromic coating layer in form of a preselected pattern,
- wherein the thermochromic coating layer further comprises a salifiable alkaline or alkaline earth compound and the salifiable alkaline or alkaline earth compound is at least partially converted into a corresponding acid salt when the liquid treatment composition is applied.
1 more element
Dependencies are inferred from the claim text.