Polyethylene Laminate Structure for Recyclable Thin Packaging Films
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Solution Overview
Problem
Existing polyethylene laminates used in packaging are difficult to recycle due to the combination of multiple materials, and there is a need for thinner films with improved mechanical properties and recyclability.
Innovation Solution
A laminate comprising a machine-direction-oriented polyethylene (MDO-PE) film and a biaxially-oriented polyethylene (BOPE) film, where the BOPE film serves as a sealing layer with a sealing initiation temperature below 128°C, allowing for reduced thickness while maintaining or enhancing mechanical properties such as strength, dart resistance, and puncture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple materials are combined to form pluri-material films, then mechanical and optical properties are improved, but recyclability deteriorates
Solution Approach 1:
The patent applies homogeneity by using only polyethylene material for all layers of the laminate, including the sealing layer. This ensures that the entire structure is made of a single material type, making it compatible with mono-material recycling streams while maintaining the necessary mechanical properties through optimized polyethylene composition and orientation.
Solution Approach 2:
The patent employs parameter changes by utilizing different orientations (uniaxial and biaxial) of the polyethylene film layers to achieve the required mechanical properties. By controlling the orientation parameters and crystallinity of each layer, the laminate achieves pluri-material-like performance while remaining a mono-material structure suitable for recycling.
2Quantity of substance
If film thickness is reduced, then plastic material consumption and recycling quantity are decreased, but mechanical properties may deteriorate
Solution Approach 1:
The patent creates a composite structure within the polyethylene laminate by combining differently oriented film layers (uniaxially oriented and biaxially oriented). This internal composite arrangement allows the thin film to achieve enhanced mechanical properties, including improved puncture resistance, dart resistance, and tensile strength, while maintaining reduced thickness and lower material consumption.
3Ease of manufacture
If uniaxially oriented film is used, then manufacturing process is simplified, but mechanical properties in cross direction are reduced
Solution Approach 1:
The patent segments the film structure into distinct functional layers: a uniaxially oriented polyethylene layer providing simplicity in manufacturing and tensile strength in the machine direction, and a biaxially oriented polyethylene layer providing enhanced mechanical properties in both machine and cross directions. This segmentation allows each layer to optimize for its specific function while the combination achieves overall performance goals.
Data Source
AI summary
The disclosure provides a laminate comprising at least a first film and a second film, wherein the first film is a machine-direction-oriented polyethylene (MDO-PE) film selected from a monolayered film or a multi-layered film comprising at least two layers, and the second film is a biaxially-oriented polyethylene (BOPE) film or a machine-direction-oriented polyethylene (MDO-PE) film; wherein the second film has a sealing initiation temperature (SIT) equal to or lower than 128° C. as determined by the method described in the description and is selected from a monolayered film or a multi-layered film comprising at least two layers and wherein the single layer or at least one layer comprises a high-density polyethylene having a density of at least 0.945 g/cm3 as determined according to ISO 1183-1:2012 at 23° C.