Transparent PET Sheet Lid with Coextruded Polyolefin and PP Layers
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Solution Overview
Problem
Existing sheet lids made from laminated materials lack sufficient rigidity for punching, often curl after punching, and require precise application of welding lacquer, which increases costs and is aesthetically undesirable, especially when using transparent PET sheets for PP packages.
Innovation Solution
A method involving a transparent polyester sheet with a coextruded polyolefin and PP polymer layer, where the polyolefin layer is between the PET and PP layers, ensuring transparency, rigidity, and eliminating the need for precise welding lacquer application, allowing for stronger and more cost-effective lids with reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a laminated sheet with multiple layers is used, then the sheet can be made from various materials, but the sheet lacks sufficient rigidity for punching and curls after punching
Solution Approach 1:
The patent uses a composite sheet structure consisting of a polyester base sheet laminated with a polyolefin layer and a PP layer. This composite construction provides the necessary rigidity to the sheet while maintaining the ability to punch and weld, resolving the contradiction between material versatility and structural strength.
2Reliability
If welding lacquer is applied to the PET sheet, then the sheet can be welded to the container, but the transparency is destroyed and costs increase
Solution Approach 1:
The patent extracts the welding function from the PET sheet surface and relocates it to a dedicated PP layer. The PP layer is positioned at the welding interface with the container, allowing welding to occur without applying lacquer to the transparent PET sheet, thus preserving transparency while maintaining weldability.
Solution Approach 2:
The PP layer acts as an intermediary between the PET sheet and the container. It provides the welding surface that interfaces with the container while the PET sheet maintains its transparency, solving the contradiction between weldability and transparency.
3Illumination intensity
If welding lacquer is applied precisely to the rim, then the transparency is preserved, but the manufacturing complexity and costs increase
Solution Approach 1:
The PP layer is integrated into the sheet structure during manufacturing, providing a self-contained welding surface. This eliminates the need for precise manual or automated application of welding lacquer during assembly, simplifying the manufacturing process while maintaining transparency.
4Weight of moving object
If a thin PET sheet is used, then the weight and material cost are reduced, but the rigidity is insufficient for punching
Solution Approach 1:
The patent uses a composite structure where the polyester base sheet is laminated with a polyolefin layer and a PP layer. This multi-layer composite provides enhanced rigidity to thin sheets, allowing weight reduction while maintaining the structural strength needed for punching operations.
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 solution provides transparent, rigid, and cost-effective sheet lids with reduced material waste and weight, enabling precise delamination and secure assembly without curling, thus simplifying the manufacturing process and enhancing the aesthetic appeal.
Implementation Method 1
an additional layer is applied onto the transparent polyester sheet (PET) in the form of a coextruded layer of a polyolefin layer and a PP polymer layer to form the sheet
Implementation Method 2
the polyolefin layer being disposed between the transparent polyester sheet (PET) and the PP polymer layer
Implementation Method 3
the sheet is punched to the final shape of the sheet lid prior to the welding to the container
Implementation Method 4
the sheet lid being welded to the container with the PP layer, which constitutes a welding layer facing toward the container
Implementation Method 5
the lid, by a subsequent separation from the container by a pull in the sheet lid, causes the PE layer to remain on the PET sheet and the PP layer to remain on the PP cup, as the PE and PP layers delaminate
Data Source
Figure 1~2
AI summary
A sheet (2) is made by the method of the invention, in particular for use for the punching of lids for packages, in that a PE layer (5a) and an additional layer PP (5b) are applied to a sheet layer (4) of polyester (PET) by coextrusion to form the finished sheet laminate (2). This ensures that the sheet (2) is transparent throughout, just as it provides the possibility of controlled delamination by separation of the PE layer (5a) from the PP layer (5b), when the sheet (2) is pulled off a package (1 ).