Hologram Embedding in Identity Cards via Composite Foil
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for embedding volume holograms into plastic card bodies, such as identity cards, result in deformation and impairment of holographic information due to high pressure and temperature during the lamination process, and lack effective protection against forgery and mechanical/chemical influences.
Innovation Solution
A method involving a two-layer composite foil structure with adhesive layers between polycarbonate foils, where a reflection volume hologram label is embedded, using a radiation-curing monomer-containing adhesive for individualization and protection, ensuring the hologram remains intact and secure within the card body during lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If volume hologram film is placed between polycarbonate foils and laminated under high pressure and temperature, then the hologram is embedded into the card body, but the hologram deforms and color changes occur due to surface roughness of the foils
Solution Approach 1:
A smooth intermediate foil is introduced between the volume hologram film and the rough polycarbonate foils during lamination. This intermediate foil acts as a mediator that transfers pressure uniformly without the surface roughness defects, preventing hologram deformation and color changes while still allowing embedding into the card body.
Solution Approach 2:
The lamination structure is segmented into multiple layers: outer rough polycarbonate foils for structural integrity, a smooth intermediate foil for hologram protection, and the volume hologram film in the middle. This segmentation allows each layer to perform its specific function without interfering with others.
2Strength
If high pressure and temperature are applied during lamination to embed the hologram, then the hologram is secured in the card body, but the holographic information is deformed and impaired
Solution Approach 1:
The smooth intermediate foil serves as a protective mediator between the high-pressure/temperature lamination process and the sensitive hologram film. It transmits the necessary pressure and heat for embedding while preventing direct contact with rough surfaces that would deform the holographic lattice structure.
Solution Approach 2:
The intermediate foil is positioned beforehand to cushion and distribute the lamination pressure uniformly across the hologram surface. This pre-positioned cushioning prevents localized stress concentrations that would cause hologram deformation during the embedding process.
3Reliability
If protective foil or lacquer is applied on the card surface to protect against mechanical and chemical influences, then protection against forgery and environmental damage is improved, but the process complexity increases and transparency may be compromised
Solution Approach 1:
The protective function is merged into the intermediate foil itself, which is already part of the lamination structure. The intermediate foil provides both the smooth surface needed for hologram protection and the mechanical/chemical protection previously requiring separate protective coatings, thereby simplifying the overall process.
Solution Approach 2:
The intermediate foil performs multiple functions simultaneously: it provides a smooth surface for uniform pressure distribution, protects the hologram from deformation, and serves as a protective layer against mechanical and chemical environmental influences, eliminating the need for separate protective coatings.
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 method allows for the embedding of holograms with personal data without altering the information content, enhancing mechanical and chemical resistance, durability, and protection against forgery, while maintaining the hologram's visual quality and adhesion strength under high temperature and pressure conditions.
Implementation Method 1
by means of a radiation-curing monomer-containing adhesive (7)
Implementation Method 2
reflection volume hologram label (1), consisting of a volume hologram label (2)
Implementation Method 3
For achieving high diffraction efficiencies of the information copied from a master by means of laser light
Implementation Method 4
into which a volume hologram label (2) entirely covered by adhesive is embedded
Implementation Method 5
The thicker and smaller the film surface, the higher the surface pressures that act on the film
Data Source
AI summary
A description is given of a document with a hologram as a security feature, in particular an identity card (12), consisting of a polycarbonate card body (10), which has a volume hologram label (2, 9) embedded therein. A description is additionally given of a method for producing the document, in which volume hologram labels (2) arranged on a carrier sheet are brought into contact with adhesive regions (4) on a thermoplastic sheet (5.1), the adhesive surfaces are cured and the carrier sheet is then removed. A second plastics sheet (5.2) is then adhesively bonded onto the first plastics sheet (5.1), bearing the hologram labels, using a second adhesive (7) in the region of the hologram labels (2) to form a two-layered sheet composite (6) which, finally, is laminated, together with further thermoplastic sheets, in a card-lamination press, under the action of pressure and temperature, to give a card body (10), individual identity cards (12) being punched out.