Security Print Media for Polymer Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional watermarking techniques are not applicable to polymer document substrates, limiting the potential for integral security features in security documents, which are typically applied post-manufacturing or using foils.
Innovation Solution
A security print medium for polymer substrates that incorporates a multi-tonal image visible in reflection and transmission, utilizing a screened working and a semi-transparent or semi-opaque first print covered by opacifying layers, allowing for integral security features similar to traditional watermarks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional watermarking techniques are used on polymer substrates, then integral security features can be formed, but these techniques are not applicable to non-fibrous polymer substrates
Solution Approach 1:
The invention changes the physical and chemical parameters of the polymer substrate by incorporating gelatine and applying controlled heat treatment. The gelatine layer is heated to specific temperatures (e.g., 40-60°C) to control its gelation and create refractive index variations, enabling watermark formation on non-fibrous polymer substrates through parameter modification rather than traditional mechanical papermaking processes
Solution Approach 2:
The invention creates a composite structure by layering gelatine over the polymer substrate. This composite material combines the properties of the polymer base with the light-interaction characteristics of gelatine, enabling watermark formation. The gelatine layer acts as an intermediate material that can be manipulated to create security features while remaining integrated with the polymer substrate
2Reliability
If security elements are applied after substrate manufacturing, then polymer substrates can have security features, but these elements are not integral to the substrate
Solution Approach 1:
The gelatine layer is applied and processed during the substrate manufacturing process itself, before the final document is produced. This preliminary action ensures the security feature becomes part of the substrate structure rather than being added later, maintaining the stability and integrity of the composition throughout the document lifecycle
Solution Approach 2:
The invention merges the security feature creation with the substrate manufacturing process by applying gelatine and using heat treatment during production. This combining of operations ensures the security element becomes integrated into the substrate rather than being a separate applied layer, achieving both security and compositional stability
3Ease of manufacture
If opacifying layers are applied to polymer substrates, then printing background is improved, but multi-tonal images visible in transmission are obscured
Solution Approach 1:
The invention applies local quality by creating specific transparent or translucent regions within the opacifying layer where the gelatine has been removed or not applied. These localized transparent areas allow the multi-tonal watermark image to be visible in transmission while the surrounding opacifying material provides the necessary printing background elsewhere on the substrate
Solution Approach 2:
The opacifying layer is segmented into different functional zones: opaque regions that provide printing background and transparent regions that allow transmission of the watermark image. This segmentation enables the coexistence of both requirements - the opacifying layer serves dual purposes of providing print background while preserving watermark visibility through strategic transparency
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
Enhances the security of polymer-based documents by providing a visible, integral security feature that changes appearance when viewed in reflection versus transmission, offering a robust and striking visual authentication method.
Implementation Method 1
the gelatine layer to a desired pattern so as to modulate the appearance of the watermark when viewed in transmitted light
Implementation Method 2
when held up to the light so as to be viewed in transmission, provides that the multi-tonal image of the first print, which was obscured in reflection by the opacifying layer(s) and the second print, is revealed and displayed to the viewer by light passing through the security print media
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3(a)~3(d)
AI summary
A security print medium is disclosed for forming security documents therefrom. The security print medium comprises a transparent or translucent polymer substrate having first and second opposing surfaces, and at least one opacifying layer disposed on the first and/or second surfaces of the polymer substrate, the or each opacifying layer being a layer of semi-opaque material. The security print medium further comprises a first print of a multi-tonal image disposed on the first and/or second surface of the polymer substrate, the first print being covered from the point of view of an observer on at least a first side of the security print medium by at least one of the opacifying layers which is disposed continuously across the multi-tonal image, and a second print of the multi-tonal image formed as a screened working comprising an array of screen elements in a colour which contrasts with that of the continuous opacifying layer. The second print is disposed on top of the continuous opacifying layer from the point of view of the observer and in alignment with the first print. When the security print medium is viewed by the observer in reflected light, the second print dominates the appearance of the multi-tonal image and when the security print medium is viewed by the observer in transmitted light, the first print dominates the appearance of the multi-tonal image.