High Refractive Index Embossing Varnish for Micro-Optical Security
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional micro-optical security elements for documents like banknotes face challenges such as thickness, brittleness, light scattering, and resolution limitations, making them difficult to produce and integrate, especially with high refractive index and color accuracy, while also being vulnerable to forgery.
Innovation Solution
The use of high refractive index embossing varnishes containing organic compounds that crosslink under radiation, combined with nanopigments and reactive dyes, to produce thinner, more secure micro-optical authenticity features with improved resolution and color variability, enabling better optical clarity and security against counterfeiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strongly curved microlenses are used to achieve good magnification, then magnification quality is improved, but manufacturing difficulty increases and microstructure size is limited
Solution Approach 1:
The patent changes the refractive index parameter of the embossing lacquer from conventional values to higher values (n > 1.5). This parameter change allows the microlenses to achieve the same magnification quality with reduced curvature, making them manufacturable by conventional embossing techniques while maintaining high magnification performance
Solution Approach 2:
The patent uses composite embossing lacquers containing high-refractive-index particles (such as TiO2, ZrO2, or SiO2) dispersed in a polymer matrix. This composite material achieves the desired high refractive index while maintaining processability and manufacturability through conventional embossing processes
2Reliability
If increased embossing depth is used to achieve required lens curvature, then optical performance is improved, but production difficulty increases
Solution Approach 1:
By changing the refractive index parameter of the embossing lacquer to higher values, the patent reduces the required embossing depth to achieve the same lens curvature. This is because higher refractive index materials bend light more effectively, requiring less physical curvature to achieve the desired optical performance
Solution Approach 2:
The patent employs thin-film embossing techniques where the high-refractive-index lacquer layer is applied as a thin coating on the substrate. This thin-film approach enables conventional embossing processes to produce the required lens shapes without the production difficulties associated with thick, deeply embossed structures
3Ease of manufacture
If conventional printing techniques are used to produce microstructure motifs, then production simplicity is maintained, but resolution is insufficient
Solution Approach 1:
The patent uses composite embossing lacquers containing fine high-refractive-index particles that can be deposited and cured to form high-resolution microstructure motifs. The particle size and distribution in the composite material enable resolution beyond conventional printing capabilities while maintaining a relatively simple production process
Solution Approach 2:
The patent replaces conventional mechanical printing processes with an embossing-based approach using high-refractive-index materials. The embossing process uses mechanical contact to transfer the microstructure pattern directly, achieving higher resolution than printing while keeping the overall process simple and direct
4Manufacturing precision
If thick microlenses are used to achieve required curvature, then magnification is improved, but light scattering increases and brilliance is reduced
Solution Approach 1:
By changing the refractive index parameter to higher values, the patent enables thinner microlenses to achieve the same magnification power. Thinner lenses have reduced path length for light transmission, thereby reducing light scattering and maintaining higher brilliance while achieving the required magnification
Solution Approach 2:
The use of composite materials with high-refractive-index particles creates lenses with enhanced light-bending capability per unit thickness. This allows the design of thinner lenses that achieve the required magnification without the light scattering problems associated with thicker conventional lenses
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 results in thinner, more durable, and high-resolution micro-optical security elements that are easier to integrate into documents, offering enhanced security against forgery with improved optical properties and reduced light scattering, while maintaining high refractive index and color accuracy.
Implementation Method 1
The embossing varnish, in particular the binder, comprises organic compounds with a high refractive index which, under the influence of radiation, undergo a polymerization reaction and crosslink or cure to form a polymer with a high refractive index
Implementation Method 2
The focusing elements of micro-optical security features are made of embossed lacquer... the microlenses and microstructures must be of approximately the same size. Furthermore, the magnification effect of the microlenses is greater the closer the microstructure is to the focal point of the lens
Implementation Method 3
Such a magnification effect is also known as moiré magnification. The basic operating principle of moiré magnification setups is described in the article 'The moire magnifier,' MC Hutley, R. Hunt, RF Stevens and P. Savander, Pure Appl. Opt. 3 (1994), pp. 133–142
Data Source
Figure 1~2
Figure 3a~4a
Figure 4b~5b
AI summary
The invention relates to a highly refractive embossing lacquer for producing micro-optical arrangements, containing at least one binding agent comprising at least one radiation-hardening connecting system consisting of one or more organic compounds. The highly refractive embossing lacquer is characterised in that at least one fraction of the organic compounds of the radiation-hardening connecting system consists of molecules having at least one element that can be polarised such that a polymer material having a refraction index of more than 1.5 is formed during radiation-hardening. The invention also relates to a security element that is produced with at least one micro-optical mark of authenticity. Micro-optical marks of authenticity, according to the invention, allow the security elements that are so thin they can be easily introduced into the valuable documents, to be produced.