Metal-Coated Magnetic Particles for Low-Viscosity Security Ink
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Solution Overview
Problem
Magnetic particles used in security ink can unintentionally increase in size and viscosity during metal coating, affecting printability and security ink properties.
Innovation Solution
A magnetic particle with a magnetic core, an intermediate metal oxide layer, and a metal coating layer, maintaining surface roughness below 0.15 μm, and controlled area of abnormal protrusions to prevent size and viscosity increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metal coating layer is formed on magnetic particles to improve brightness, then the color brightness is improved, but the particle size increases beyond the expected range
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where each layer has specific properties: the magnetic core provides magnetic properties, the intermediate metal oxide layer provides a smooth base, and the metal coating layer provides brightness. This localized functional distribution allows brightness improvement without excessive particle size increase.
Solution Approach 2:
The patent uses composite materials by combining magnetic material core with metal oxide intermediate layer and metal coating layer. This composite structure allows the particle to simultaneously achieve magnetic properties, smooth surface, and bright color while controlling overall particle size within acceptable ranges for security ink application.
2Reliability
If magnetic particles are used in security ink, then security function is provided, but the viscosity of security ink significantly increases, damaging printability
Solution Approach 1:
The patent changes physical parameters of magnetic particles by controlling surface roughness to 0.15 μm or less and optimizing particle size distribution. These parameter changes reduce the particles' impact on ink viscosity, allowing the ink to maintain good flow properties and printability while still providing security functions through magnetic detection.
3Manufacturing precision
If classification operation is performed to select particles of predetermined size, then particle size control is improved, but the particle size may still increase during metal coating operation
Solution Approach 1:
The patent applies preliminary action by forming an intermediate metal oxide layer on the magnetic core before applying the metal coating layer. This intermediate layer serves as a buffer that prevents the metal coating from significantly increasing the particle size, thereby maintaining particle size stability even after coating operations.
Solution Approach 2:
The intermediate metal oxide layer acts as a cushioning layer between the magnetic core and the metal coating layer. This beforehand cushioning prevents the metal coating from directly adding to the core particle size, thus compensating for potential size increases and maintaining overall particle size within acceptable ranges.
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 magnetic particle maintains uniform size and low viscosity, ensuring stable printability and security ink performance.
Implementation Method 1
the metal coating layer may be produced by electroless plating using ethylenediamine as a complexing agent
Implementation Method 2
The reflectivity of the magnetic particle for 900 nm light may be 60% or more
Data Source
AI summary
Disclosed are a magnetic particle and a security ink containing the same. The magnetic particle includes a magnetic core, and a metal coating layer formed outside the magnetic core. The magnetic particle has a surface roughness (Ra) of 0.15 μm or less. The magnetic particle according to the present invention is suitable for application to a security ink because an abnormal increase in particle size does not occur after the metal coating layer is formed.