Film Laminate Adhesion via Partial Solidification
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Solution Overview
Problem
Existing laminated packaging materials face challenges with adhesion between thin and sensitive layers, particularly around pre-cut holes in the paperboard, leading to issues like wrinkles, tensions, air entrapments, and defects such as pin-holes, which affect the robustness and reliability of the packaging.
Innovation Solution
A method involving the preformation of a polymer film by casting molten polymer onto a cooling roller to partially solidify it before laminating it onto a substrate, such as a metal foil or barrier film, within a lamination nip, ensuring improved adhesion and reducing defects by avoiding the application of hot molten polymer directly onto unsupported areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot molten polymer is applied directly onto thin aluminium foil in unsupported areas (around pre-cut holes), then lamination adhesion is achieved, but wrinkles, tensions, and defects such as pin-holes occur
Solution Approach 1:
The patent introduces a support layer (intermediary) between the hot molten polymer and the thin aluminium foil in unsupported areas. This support layer prevents the foil from contacting the hot polymer directly, eliminating the thermal shock and mechanical stress that cause wrinkles, tensions, and pin-holes, while still allowing adhesion to occur in supported areas where the polymer can bond properly to the foil.
Solution Approach 2:
The patent applies different treatment to different areas of the aluminium foil: in supported areas, the hot molten polymer is allowed to contact and adhere to the foil; in unsupported areas (around pre-cut holes), a support layer is introduced to prevent direct contact. This local differentiation of adhesion conditions resolves the contradiction by maintaining reliability where possible while preventing defects where necessary.
2Reliability
If thin aluminium foil is used for oxygen barrier, then oxygen barrier properties are improved, but the foil becomes delicate and prone to breakage during lamination and handling
Solution Approach 1:
The patent introduces a support layer beforehand in unsupported areas to cushion and protect the thin aluminium foil from mechanical stress and thermal shock during the lamination process. This pre-protective measure prevents breakage and deformation of the delicate foil, allowing thin foil to be used without compromising its robustness during handling and processing.
3Productivity
If high web speeds are used in lamination operations, then productivity is improved, but adhesion problems and defects increase
Solution Approach 1:
The support layer acts as an intermediary that stabilizes the lamination process in unsupported areas, allowing high web speeds to be maintained without compromising adhesion quality. By preventing foil contact with hot polymer in critical areas, the support layer eliminates the variability and defects that would otherwise increase at high speeds, enabling consistent adhesion even at elevated productivity levels.
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 enhances the quality of the laminated packaging material by reducing wrinkles, tensions, and defects, resulting in improved adhesion and a more robust packaging structure with better oxygen barrier properties, suitable for aseptic storage of liquid food products.
Implementation Method 1
casting the polymer film by applying a molten polymer material onto a cooling roller to at least partially solidify the molten polymer material to form the polymer film
Implementation Method 2
to at least partially solidify the molten polymer material to form the polymer film
Implementation Method 3
The lamination nip is defined by two rollers rotating towards and pressing on each other
Implementation Method 4
laminating the polymer film onto the web of the substrate to provide the film laminate
Data Source
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AI summary
A method for providing a film laminate comprising a substrate (112) and a polymer film (123), and suitable for forming a part of a laminated packaging material is provided. The method comprises forwarding a web of the substrate (112) to pass through a lamination nip (130a). The method further comprises casting the polymer film by applying a molten polymer material (123) onto a cooling roller (122) to at least partially solidify the molten polymer material to form the polymer film. Furthermore, the method comprises directly forwarding the polymer film to pass through the lamination nip (130a), thereby laminating the polymer film onto the web of the substrate.