Optical Effect Layer Production via Bi-Axial and Mono-Axial Magnetic Orientation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing processes for producing optical effect layers (OELs) using magnetically oriented pigment particles are limited in achieving high chroma, brightness, and contrast, particularly with small platelet-shaped particles, which are traditionally considered inferior for producing high-quality images.
Innovation Solution
A process involving the application of a coating composition with platelet-shaped magnetic or magnetisable pigment particles on a substrate, followed by bi-axial and mono-axial orientation using dynamic and static magnetic fields, respectively, and subsequent hardening to fix the particle orientations, allowing for the production of OELs with high chroma, brightness, and contrast, regardless of particle size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If small platelet-shaped pigment particles are used, then flexibility and versatility of printing applications are improved, but chroma, brightness, and contrast deteriorate
Solution Approach 1:
The orientation process is segmented into two distinct stages: bi-axial orientation followed by mono-axial orientation. This segmentation allows small particles to first achieve planar alignment (bi-axial) and then precise linear alignment (mono-axial), resolving the contradiction by enabling small particles to achieve both flexibility and high optical quality through sequential orientation steps
Solution Approach 2:
The bi-axial orientation is performed as a preliminary action before mono-axial orientation. This preliminary planar alignment of small particles creates a favorable starting condition for the subsequent mono-axial orientation, allowing small particles to achieve high brightness and contrast without sacrificing their size-related flexibility advantages
2Illumination intensity
If large pigment particles are used, then chroma and brightness are improved, but flexibility and adaptability deteriorate
Solution Approach 1:
The conventional wisdom is inverted: instead of using large particles to achieve high chroma and brightness, the invention uses small particles with a two-stage orientation process. This inversion resolves the contradiction by achieving high optical quality through precise orientation control rather than particle size, thereby maintaining flexibility and adaptability
Solution Approach 2:
The invention changes the orientation parameters through two distinct magnetic field applications: first bi-axial orientation parameters, then mono-axial orientation parameters. This parameter change enables small particles to achieve optical properties previously only attainable with large particles, resolving the contradiction between particle size and optical quality
3Reliability
If magnetic orientation process is applied, then security and anti-counterfeit properties are improved, but device complexity increases
Solution Approach 1:
The magnetic orientation device is segmented into two functional units: a bi-axial orientation device and a mono-axial orientation device. This segmentation allows each device to be optimized for its specific function, managing complexity by dividing the overall orientation task into two specialized, manageable components that together achieve high security properties
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 process enables the use of small platelet-shaped particles to produce high-quality OELs with improved reflectivity and flexibility, enabling more versatile printing applications while maintaining or enhancing optical properties and resolution.
Implementation Method 1
exposing the coating composition to a dynamic magnetic field of a first magnetic-field-generating device so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetisable pigment particles
Implementation Method 2
exposing the coating composition of step b) to a static magnetic field of a second magnetic-field-generating device, thereby mono-axially re-orienting at least a part of the platelet-shaped magnetic or magnetisable pigment particles
Data Source
AI summary
The disclosure relates to the field of the protection of security documents, such as for example banknotes and identity documents against counterfeit and illegal reproduction. In particular, the present disclosure provides processes for producing optical effect layers (OELs) on a substrate and OELs obtained thereof, said process including two magnetic orientation steps: a step of exposing a coating composition having platelet-shaped magnetic or magnetisable pigment particles to a dynamic magnetic field of a first magnetic-field-generating device so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetisable pigment particles, and a step of exposing the coating composition to a static magnetic field of a second magnetic-field-generating device, thereby mono-axially re-orienting at least a part of the platelet-shaped magnetic or magnetisable pigment particles.