Thermoplastic Hinge Printing via Intermediary Transfer Lamination
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Solution Overview
Problem
The challenge is to print security features on the hinge layer of identification documents, such as passports, which is made of thermoplastic materials with good elasticity properties, as existing printing processes like offset printing are not compatible with these materials, leading to deformation and poor print quality.
Innovation Solution
A method involving a first thermoplastic sheet for the hinge and a second thermoplastic sheet with printed security features, laminated together at a temperature and pressure below the melting point of the second sheet, allowing the security features to be transferred onto the first sheet, enabling printing with a range of processes including offset printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If offset printing is used to print security features on the hinge layer, then printing precision and design quality are improved, but the thermoplastic material deforms and is destroyed by mechanical rollers
Solution Approach 1:
A release sheet is introduced as an intermediary carrier between the printing system and the thermoplastic hinge layer. The release sheet receives the offset print and transfers it to the hinge layer during lamination, protecting the thermoplastic material from direct contact with mechanical rollers while enabling high-quality printing
Solution Approach 2:
The security features are printed on the release sheet before lamination occurs. This preliminary printing action allows the use of offset printing processes on the release sheet without exposing the thermoplastic hinge layer to damaging mechanical forces, and the print is subsequently transferred to the hinge layer
2Adaptability or versatility
If thermoplastic polyurethane is used for the hinge layer, then elasticity and flexibility are improved, but compatibility with conventional printing processes is worsened
Solution Approach 1:
The release sheet serves as a mediator that is compatible with conventional offset printing processes while the thermoplastic polyurethane hinge layer maintains its elasticity and flexibility. The printing is performed on the release sheet which then transfers the image to the hinge layer during lamination
Solution Approach 2:
The printing process parameters are changed by printing on the release sheet rather than directly on the thermoplastic material. This parameter change enables the use of standard offset printing processes while preserving the elastic properties of the thermoplastic polyurethane hinge layer
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 method allows for high-quality printing of security features on a wide range of materials, including thermoplastic polyurethane, ensuring durability and resistance to counterfeiting, while maintaining the elasticity of the hinge layer.
Implementation Method 1
laminating the first sheet and the at least one second sheet at a temperature and a pressure lower than the melting point of the second thermoplastic material and allowing to transfer the printed security feature to the first sheet
Data Source
Figure 1
AI summary
The invention relates to a method of printing a sheet (4) intended to form an attachment part (6) of a data page for an identification document, characterized in that it comprises the following steps: - providing a first sheet (4) made of a first thermoplastic material and intended to form the attachment part (6), - placing at least one second sheet (10) made of a second thermoplastic material at least locally against one face of the first sheet (4), the at least one second sheet (10) comprising at least one security feature (12) printed on it, - laminating the first sheet (4) and the at least one second sheet (10) at a temperature and a pressure lower than the melting point of the second thermoplastic material and allowing to transfer the printed security feature (12) to the first sheet (4).