Capsule Luminescent Ink for Security Printing
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Solution Overview
Problem
Existing luminescent printing inks for security printing face challenges in achieving reliable visual and machine authenticity testing due to the limitations of inorganic phosphors, such as short luminescence intensity, difficulty in printing intricate patterns, mechanical abrasion, and separation issues in ink fountains.
Innovation Solution
A luminescent printing ink is developed that combines fluorescent and phosphorescent substances within capsule luminescence pigments, each with a core and shell structure, ensuring equal chemical stability and lightfastness, and allowing for adjustable intensity and color correspondence for enhanced visual and machine readability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic phosphors are used to achieve machine-detectable luminescence, then chemical stability and lightfastness are improved, but luminescence intensity for visual verification deteriorates
Solution Approach 1:
The patent combines fluorescent substances and phosphorescent substances within the same capsule structure to achieve both high visual luminescence intensity (from fluorescent component) and sufficient machine-detectable phosphorescence (from phosphorescent component), resolving the contradiction between visual brightness and machine readability
Solution Approach 2:
The invention uses composite capsule structures containing both fluorescent and phosphorescent materials, creating a hybrid luminescent system that exhibits properties of both material types - immediate fluorescent response for visual verification and delayed phosphorescent emission for machine detection
2Reliability
If inorganic phosphors are used to achieve machine-detectable luminescence, then chemical stability is improved, but printability and ability to print intricate patterns deteriorates
Solution Approach 1:
The patent changes the physical parameters of the luminescent materials by encapsulating them in polymer capsules, which modifies their flow properties, reduces aggregation, and improves their ability to be printed in intricate patterns while maintaining chemical stability
Solution Approach 2:
The use of flexible polymer capsule shells allows the luminescent materials to be processed and printed more easily, as the capsules can deform during printing operations and maintain uniform distribution in the ink medium
3Reliability
If inorganic phosphors are used to achieve machine-detectable luminescence, then chemical stability is improved, but mechanical abrasion and wear in printing machines increases
Solution Approach 1:
The flexible polymer capsule shells protect the hard inorganic phosphor particles from mechanical abrasion during printing operations, reducing wear on printing machine components while maintaining the chemical stability and luminescence properties of the phosphors
4Reliability
If inorganic phosphors are used to achieve machine-detectable luminescence, then chemical stability is improved, but separation in ink fountain during long printing operations increases
Solution Approach 1:
The patent changes the density and surface properties of the luminescent particles through encapsulation, matching them more closely with the ink medium to prevent separation and settling during long printing operations and storage periods
5Reliability
If capsule luminescence pigments are used to improve chemical stability, then chemical stability is improved, but luminescence intensity deteriorates
Solution Approach 1:
The patent merges fluorescent and phosphorescent substances within the same capsule to achieve both high visual luminescence intensity from the fluorescent component and sufficient machine-detectable intensity from the phosphorescent component, while maintaining chemical stability through encapsulation
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 ink achieves high visual brightness and machine-readable luminescence intensity, maintaining consistent color impression and stability under various environmental conditions, thus overcoming the limitations of previous inks and providing reliable security features.
Implementation Method 1
fluorescent substances are generally less suitable for machine authenticity testing because of their short decay times
Implementation Method 2
phosphorescent substances are usually used for machine-detectable security features, and these emit light with a characteristic decay time even after the excitation radiation has been switched off
Data Source
AI summary
A luminescent printing ink for security printing includes a fluorescent substance and a phosphorescent substance which each luminesce in the visible spectral range when excited with non-visible excitation light. The printing ink contains one or more capsule luminescent pigment varieties, each of which has a core, a shell encapsulating the core and a luminescent substance present in the core. The fluorescent substance and the phosphorescent substance are each present as a luminescent substance in the core of one or more of the capsule luminescent pigment varieties so that the capsule luminescent pigments form fluorescent capsule luminescent pigments and/or phosphorescent capsule luminescent pigments. The luminescences of the fluorescent and the phosphorescent capsule luminescence pigments have the same light-fastness and the same chemical stability, and their luminescences visually produce a substantially matching colour impression.