TPU Membrane with Reactive Cap Layer for Adhesion and Recyclability
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Solution Overview
Problem
Existing membranes used in gas-filled bladders and cushioning devices lack durability and recyclability, with thermoset materials not being recyclable and thermoplastic polymers, like TPUs, facing challenges in achieving a balanced set of physical and mechanical properties for demanding applications.
Innovation Solution
A membrane structure comprising a core layer of alternating TPU and barrier microlayers, with a reactive TPU cap layer that bonds covalently to adjacent rubber layers using curing agents, enhancing adhesion and durability, and allowing for recyclability of thermoplastic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermoset materials are used to achieve balanced physical and mechanical properties, then durability and performance are improved, but recyclability deteriorates
Solution Approach 1:
The membrane is divided into multiple functional layers including TPU layers and barrier layers with distinct purposes. The TPU layers provide flexibility and recyclability while barrier layers provide gas transmission resistance, allowing each segment to optimize its specific function without compromising overall performance
Solution Approach 2:
The invention uses composite material structures combining TPU (thermoplastic) with barrier materials like EVOH or nylon. This composite approach allows the membrane to achieve the balanced physical and mechanical properties traditionally associated with thermoset materials while maintaining the recyclability advantage of thermoplastics
2Ease of manufacture
If thermoplastic polymers like TPU are used to enable recyclability, then recyclability is improved, but physical and mechanical properties deteriorate
Solution Approach 1:
By combining TPU with high-performance barrier materials in a multi-layer composite structure, the invention achieves physical and mechanical properties sufficient for demanding applications while preserving the recyclability of the TPU components
Solution Approach 2:
The invention modifies the structural parameters of TPU by creating multi-layer configurations with specific layer thicknesses and compositions, transforming it from a material with limited standalone performance to one that achieves balanced properties through structural optimization
3Reliability
If reactive cap layers with curing agents are added to bond rubber layers, then adhesion and durability are improved, but device complexity increases
Solution Approach 1:
The cap layer integrates multiple functions into a single component: it provides structural integrity, serves as an adhesive interface for bonding rubber layers through curing agents, and maintains the overall membrane flexibility. This merging eliminates the need for separate adhesive layers or additional bonding components
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 membrane exhibits excellent resistance to fatigue failure, superior adhesion to rubber and non-polar substrates, and very low gas transmission rates, making it suitable for various applications including footwear, tires, and inflatable structures with improved recyclability.
Implementation Method 1
The cap layer is reactive, such that it can bond (e.g., covalently) to another layer (e.g., a rubber layer...) that is placed adjacent and directly in contact with the cap layer
Implementation Method 2
A membrane structure comprising a core layer of alternating TPU and barrier microlayers... very low gas transmission rates
Data Source
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AI summary
Membranes (110) and methods for producing them are disclosed. The membranes (110) comprise a core layer (124) comprising a composite of alternating thermoplastic polyurethane (TPU) and barrier microlayers, and they comprise at least one cap layer (122,126) that is bonded to the core layer (124) or a structural layer (112,120). In some embodiments, at least the cap layer (122,126) comprises a polydiene polyol-based TPU. The membrane (110) may further comprise a rubber layer bonded to the cap layer.