Magnetic Assemblies for Oriented Non-Spherical Pigment Optical Effect Layers
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Solution Overview
Problem
Existing security features, particularly optical effect layers (OELs), face challenges in producing high-quality, eye-catching, and dynamic loop-shaped effects on substrates that are difficult to counterfeit and reproduce on a mass scale, with issues related to blurred ring edges and low magnetic field intensity due to the use of single magnets.
Innovation Solution
A process involving a radiation curable coating composition with non-spherical magnetic or magnetizable pigment particles is applied to a substrate and exposed to a magnetic field generated by a magnetic assembly comprising multiple magnets and a flat pole piece, orienting the particles to create an optical effect of a moon crescent moving and rotating upon tilting, which is then cured to fix their positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnet is used to generate the magnetic field for orienting pigment particles, then the device complexity is reduced, but the magnetic field intensity decreases rapidly with distance and the ring edges become blurred
Solution Approach 1:
The single magnet is segmented into multiple magnets (first magnet and second magnet) arranged in a specific configuration. This segmentation allows each magnet to contribute to the overall magnetic field, maintaining high field intensity at the substrate while reducing the rapid decay problem of a single magnet, thereby producing sharp ring edges.
Solution Approach 2:
Multiple magnets are combined in a specific arrangement where their magnetic fields work together to create the desired orientation pattern. The combination of magnetic fields from multiple sources produces a more stable and intense field distribution compared to a single magnet, achieving both high field intensity and sharp features.
2Device complexity
If a single magnet is used to produce the magnetic field, then the device structure is simpler, but the magnetic field intensity decreases rapidly with increasing distance from the magnet
Solution Approach 1:
The magnetic field generation is segmented into multiple magnet sources positioned at different locations. This segmentation allows the magnetic field to be maintained at higher intensity over greater distances from any individual magnet, as the combined effect of multiple magnets compensates for the distance-related intensity loss.
Solution Approach 2:
The magnetic field generation transitions from a single-point source to a distributed multi-point source in three-dimensional space. By positioning magnets at different spatial locations and orientations, the system creates a more uniform and extended magnetic field distribution that maintains intensity over larger working distances.
3Device complexity
If only one rotating or static magnet is used for particle alignment, then the production process is simpler, but the change in orientation of particles is relatively soft resulting in blurred features
Solution Approach 1:
The orientation control is segmented into multiple magnetic sources that create distinct field gradients. This segmentation produces sharper transitions in the magnetic field direction, causing more abrupt and well-defined particle orientation changes across the substrate, resulting in crisp featured edges.
Solution Approach 2:
The magnetic field generating devices are positioned asymmetrically with different orientations (first magnet with first orientation, second magnet with second orientation). This asymmetric arrangement creates asymmetric magnetic field gradients that produce well-defined, non-uniform particle orientation patterns with sharp features rather than soft transitions.
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 provides a high-quality, eye-catching optical effect that is resistant to counterfeiting and easy to verify, with improved magnetic field intensity and clarity of ring edges, making it difficult to produce on a mass scale without specialized equipment.
Implementation Method 1
exposing the radiation curable coating composition to a magnetic field of a magnetic assembly (x00) comprising: a) a first magnetic-field generating device (x30) having its North-South magnetic axis substantially perpendicular to the substrate (x20) surface
Implementation Method 2
coating composition comprising non-spherical magnetic or magnetizable pigment particles
Implementation Method 3
at least partially curing the radiation curable coating composition of step ii) to a second state so as to fix the non-spherical magnetic or magnetizable pigment particles in their adopted positions
Data Source
Figure 1~2
Figure 3~3E
Figure 4~5C
AI summary
The present invention relates to the field of magnetic assemblies, magnetic apparatuses and processes for producing optical effect layers (OEL) comprising magnetically oriented non-spherical magnetic or magnetizable pigment particles on a substrate and providing an impression of a crescent moon-shaped element moving or rotating upon tilting the optical effect layer (OEL). In particular, the present invention relates to magnetic assemblies, magnetic apparatuses and processes for producing said OELs as anti-counterfeit means on security documents or security articles or for decorative purposes.