Low Energy UV Curable Offset Ink for Security Printing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional UV-curable inks used in security document printing suffer from slow curing and set-off issues due to low energy curing systems and the presence of pigments, which hinder efficient polymerization and lead to delays in multi-step printing processes.
Innovation Solution
Development of low energy radically curable offset and letterpress printing inks utilizing specific photoinitiators and (meth)acrylate compounds, combined with machine-readable materials and fillers, that can be cured efficiently with UV lamps in the 280-400 nm range, ensuring rapid surface and through-cure properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional UV-curable inks are used in security document printing, then the printing process can be performed, but the curing is slow and set-off issues occur due to low energy curing systems and the presence of pigments
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by incorporating specific photoinitiators (such as TPO, BAPO, or a combination thereof) and (meth)acrylate compounds with optimized ratios. This parameter change enables the ink to cure rapidly under low energy UV irradiation (280-400 nm), resolving the contradiction between printing speed and curing efficiency by ensuring complete curing within the printing cycle without set-off issues
Solution Approach 2:
The patent creates a composite ink system combining multiple components: photoinitiators, (meth)acrylate compounds, pigments, and additives in specific proportions. This composite formulation synergistically improves both printing performance and curing efficiency, allowing high-speed printing while maintaining reliable curing even in the presence of pigments that would otherwise hinder polymerization
2Reliability
If multiple security features are applied in sequence, then comprehensive security protection is achieved, but the multi-step printing process is delayed due to drying periods between steps
Solution Approach 1:
The patent enables continuous printing operations by ensuring that each security feature layer cures rapidly enough to prevent set-off during the next printing step. The optimized photoinitiator system allows the printing process to continue without interruption or extended drying periods, maintaining both the completeness of multiple security features and the efficiency of the overall printing timeline
Solution Approach 2:
The patent incorporates photoinitiators and curing agents in advance within the ink formulation itself, so that curing begins immediately upon UV exposure during the printing process. This preliminary preparation of curing capability eliminates the need for separate drying periods between printing steps, allowing multiple security features to be applied in continuous sequence
3Manufacturing precision
If high pressure is applied during intaglio printing, then the intaglio printing quality is improved, but set-off issues are pronounced when offset inks are not completely dried
Solution Approach 1:
The patent modifies the chemical composition of the offset ink by incorporating specific photoinitiators and (meth)acrylate compounds that enable rapid curing upon UV exposure. This parameter change ensures that the offset ink layer is completely cured before the high-pressure intaglio printing step, eliminating set-off issues while allowing the intaglio process to proceed with the necessary pressure for high printing quality
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
The solution enables high-speed printing of security features with improved curing efficiency and reduced set-off, allowing for faster production of secure documents without compromising quality.
Implementation Method 1
UV radically curable pigmented offset printing inks and UV radically curable pigmented letterpress printing inks... utilizing specific photoinitiators and (meth)acrylate compounds, combined with machine-readable materials and fillers, that can be cured efficiently with UV lamps in the 280-400 nm range
Data Source
AI summary
The present invention relates to the field of low energy radically curable inks for offset or letterpress printing of security documents. In particular, the invention relates to low energy radically curable offset or letterpress printing inks for offset or letterpress printing on a substrate or security document, said low energy radically curable inks having a viscosity in the range of about 2.5 to about 25 Pa s at 40° C. and 1000 s−1 and comprising radically curable (meth)acrylate compounds, one or more one or more photoinitiators of formula (I), one or more machine readable materials and one or more fillers and/or extenders.