Screen Printing Effect Colours on Valuable Documents
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for applying optically variable security elements to documents of value, such as banknotes, face challenges in achieving a smooth substrate surface for optimal print quality, especially when intaglio printing is done after screen printing, leading to time-consuming and costly processes.
Innovation Solution
A method where a second area of the paper substrate is smoothed before applying ink with optically variable pigments, allowing the color to appear glossy in the overlap area and matte outside, enhancing surface smoothing and print quality, particularly in screen printing, and allowing flexibility in printing sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a primer is applied in screen printing to smooth the substrate surface before effect color printing, then surface smoothness and print quality are improved, but the process requires specialized machines with intermediate dryers and additional printing cycles
Solution Approach 1:
The patent divides the substrate surface treatment into two separate areas: a first area that remains rough and a second area that is smoothed. This segmentation allows different surface treatments in different regions without requiring complex machine configurations or multiple printing cycles, as the smoothing is achieved through selective mechanical treatment rather than a comprehensive primer application process.
Solution Approach 2:
The patent applies surface smoothing to the second area before the screen printing of the effect color is performed. This preliminary surface preparation ensures that when the effect color is applied to the smoothed area, it achieves optimal adhesion and visual appearance, while avoiding the need for complex intermediate drying processes or specialized machine configurations.
2Manufacturing precision
If calendering is used to smooth the paper substrate, then surface smoothness is improved, but the printing sequence is fixed with intaglio printing before screen printing
Solution Approach 1:
The patent segments the substrate surface into a first area (rough) and a second area (smoothed), allowing selective surface treatment independent of the printing sequence. This enables flexibility in arranging intaglio and screen printing in any order, as the smoothed area is created locally rather than through a global calendering process that fixes the printing sequence.
Solution Approach 2:
The patent applies surface smoothing only to the second area where effect color printing is required, rather than smoothing the entire substrate. This local quality approach allows the rest of the substrate to maintain its original properties and enables flexible printing sequences, as the smoothed region is prepared specifically for screen printing regardless of when intaglio printing occurs.
3Manufacturing precision
If two separate passes through the press are used for machines without intermediate dryers, then surface smoothing is achieved, but the process becomes time-consuming and costly
Solution Approach 1:
The patent performs surface smoothing of the second area as a preliminary step before screen printing the effect color. By preparing the surface in advance through selective mechanical smoothing rather than requiring multiple printing passes, the process achieves the desired surface quality in a single integrated operation, improving productivity and reducing costs.
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 approach improves print quality and reduces costs by enabling partial surface smoothing before screen printing, allowing for more flexible printing sequences and potentially eliminating the need for additional printing cycles.
Implementation Method 1
the optically variable effect, which can be visually and easily and clearly recognized... the viewer perceives a specific color that changes as the viewing angle changes
Implementation Method 2
one color is mixed with pigments in the form of thin-layer elements, the thin-layer elements consisting of a reflector layer, a dielectric and an absorber layer
Data Source
Figure 1~1b
Figure 2~2b
AI summary
The invention relates to a method for applying an optically variable security element to the top surface of a substrate of a security document, wherein the top surface of the substrate is made of paper. The optically variable security element consists of an ink containing optically variable pigments, which is printed onto a first area of the top surface of the paper substrate. According to the invention, prior to the printing of the ink containing optically variable pigments, a second area of the top surface of the paper substrate is smoothed, wherein the second area with the smoothed surface and the first area with the ink containing optically variable pigments overlap at least partially. Thus, the ink with optically variable pigments has a different appearance to an observer in the area of overlap than outside the overlap.