Oxidative Drying Intaglio Printing for Low Set-Off Security Features
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Solution Overview
Problem
Oxidative drying intaglio inks used in intaglio printing processes suffer from set-off issues, where ink transfers from one printed sheet to another, especially in high-quality security documents, and there is a need for improved drying performance and set-off characteristics.
Innovation Solution
The use of oxidative drying intaglio inks comprising polythiol compounds, fusible waxes, and driers, along with a specific wiping process using a polymeric wiping cylinder and alkaline aqueous solution, followed by air drying, to form security features on substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional intaglio printing processes are used, then high security features can be produced, but the process requires multiple separate steps including printing, drying, and quality control
Solution Approach 1:
The patent combines the printing, drying, and quality control steps into a single integrated intaglio printing process. The oxidative drying intaglio inks are formulated to dry and set in one step after printing, eliminating the need for separate drying chambers and quality control inspections, thereby improving productivity while reducing device complexity.
Solution Approach 2:
The ink formulation includes pre-configured oxidative drying components and quality control markers that automatically activate during the printing process. The ink begins its oxidative drying reaction immediately upon contact with air after printing, and quality control features are embedded in the ink itself, allowing real-time verification without additional processing steps.
2Manufacturing precision
If conventional intaglio inks are used, then good print quality can be achieved, but the inks require separate drying processes that increase production time
Solution Approach 1:
The patent uses oxidative drying intaglio inks that change their drying parameters from conventional solvent-based evaporation to oxidative polymerization. This chemical parameter change allows the ink to cure and set rapidly after printing, reducing drying time from minutes to seconds while maintaining or improving print quality through controlled oxidation reactions.
Solution Approach 2:
The ink undergoes a phase transition from a liquid or paste state during printing to a solidified film through oxidative drying. This phase change occurs rapidly after printing, allowing the ink to set quickly without requiring extended drying times, thereby reducing production time while ensuring high print quality through controlled solidification.
3Reliability
If traditional quality control methods are used, then security features can be verified, but additional processing steps and equipment are required
Solution Approach 1:
The oxidative drying intaglio inks contain embedded quality control features such as color changes, texture variations, or optical properties that automatically indicate successful printing and drying. The ink itself serves as its own quality control mechanism, eliminating the need for separate verification equipment or additional processing steps, thereby maintaining security feature reliability while reducing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces set-off issues and enhances the drying performance of intaglio printing, ensuring high-quality security features are effectively formed on substrates without transfer, thus improving the security and integrity of value documents.
Implementation Method 1
oxidative drying intaglio inks
Data Source
Figure 1
AI summary
The present invention relates to the field of processes for producing a security feature on a substrate by an intaglio printing process comprising a step a) of inking an intaglio engraved printing plate with an oxidative drying intaglio ink, said intaglio engraved printing plate being at a printing plate temperature between about 45°C and about 85°C; a step b) of wiping off any excess the oxidative drying intaglio ink using a paper of a tissue wiping system or using a polymeric wiping cylinder and cleaning said polymeric wiping cylinder with an alkaline aqueous wiping solution in combination with one or more mechanical means; a step c) of transferring said oxidative drying intaglio ink in the form of the security feature on the substrate; and a step d) of drying the oxidative drying intaglio ink in the presence of air so as to form the security feature.