Recyclable Flexible Barrier Laminates with Water-Soluble Oxygen-Barrier Layer
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Solution Overview
Problem
Current flexible packaging materials with high oxygen barrier properties, such as multilayer mixed plastics and metals, cannot be recycled effectively due to the inability to separate individual components, leading to undesirable colors and incompatible materials in reclaimed plastic.
Innovation Solution
A flexible barrier laminate composed of a single polymer, with a water-soluble oxygen-barrier layer interposed between two polymer layers, allowing for easy separation and recycling by dissolving the oxygen-barrier layer with an aqueous wash, thus enabling the recycling of at least 95% of the package without separating individual layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multilayer mixed plastic and metal composition is used to achieve high oxygen barrier properties, then oxygen barrier performance is improved, but recyclability deteriorates because individual components cannot be separated
Solution Approach 1:
The laminate is segmented into distinct functional layers: a water-soluble oxygen barrier layer (polyvinyl alcohol) and a recyclable polymer matrix (polyethylene). This segmentation allows the barrier function to be provided by a removable component while the main structure remains recyclable.
Solution Approach 2:
The oxygen barrier layer is extracted as a separate, water-soluble component that can be removed from the laminate structure through aqueous washing. This extraction enables the polyethylene layers to be recovered and recycled without contamination from barrier materials, inks, or adhesives.
2Ease of manufacture
If 95% mono-plastic material is used to improve recyclability, then ease of recycling is improved, but oxygen barrier performance deteriorates due to the remaining 5% barrier materials, inks and adhesives
Solution Approach 1:
A water-soluble intermediary layer (polyvinyl alcohol) is introduced between the polyethylene layers. This intermediary provides the necessary oxygen barrier function during use, then acts as a removable mediator during recycling by dissolving in water to release the polyethylene layers for pure recycling.
Solution Approach 2:
The invention changes the chemical parameter of the barrier layer by using a water-soluble polymer (polyvinyl alcohol) instead of traditional hydrophobic barrier materials. This parameter change enables the barrier layer to be selectively removed through aqueous treatment, resolving the conflict between barrier performance and recyclability.
3Ease of manufacture
If water-soluble oxygen-barrier layer is added to enable separation and recycling, then recyclability is improved, but laminate structure complexity increases
Solution Approach 1:
The invention exploits the phase transition of the polyvinyl alcohol layer from solid (providing barrier function) to dissolved state (enabling separation). This phase transition upon water exposure automatically triggers the separation process without requiring additional mechanical or chemical treatment steps, keeping the overall process simple despite the layered structure.
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 allows for the recycling of flexible packages without the need to separate layers, maintaining high oxygen barrier properties and producing clean, reusable polymer pieces, enhancing the quality and recyclability of packaging materials.
Implementation Method 1
The second polymer layer is configured to be separated from the first polymer layer by the application of an aqueous wash to the flexible barrier laminate to cause the first oxygen-barrier layer to dissolve
Data Source
AI summary
Disclosed are recyclable flexible package and a method of recycling such packages. The flexible package includes a hollow body defining an interior chamber for holding an oxygen sensitive product. The body is formed of a laminated film formed of two layers of a single polymer material, e.g., polyethylene, and at least one interposed barrier layer, e.g., polyvinyl alcohol, that is resistant to the passage of oxygen therethrough and which is water-soluble. The single polymer constitutes at least 95% by weight of the laminated film, whereupon the package is suitable for recycling without requiring separation of the materials thereof by shredding the laminated film and subjecting those pieces to an aqueous wash to dissolve the barrier layer.