Multi-Layered Film Bladders for Crack-Resistant Gas Retention
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Solution Overview
Problem
Existing gas-barrier layers in fluid-filled bladders used for cushioning elements are prone to cracking and increased gas transmission rates due to repeated flexing, leading to reduced durability and visibility of defects.
Innovation Solution
Employing a multi-layered film structure with thinner gas-barrier layers (≤0.75 micrometers) and alternating elastomeric layers to enhance flexibility and maintain gas-barrier properties, reducing the likelihood of cracking and maintaining low gas transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gas-barrier layers are used in fluid-filled bladders, then gas-barrier properties are maintained, but the layers are prone to cracking and show visible defects after repeated flexing
Solution Approach 1:
The gas-barrier layer is divided into multiple sub-layers (first gas-barrier sub-layer and second gas-barrier sub-layer) with different compositions and properties. The first sub-layer provides primary gas barrier function while the second sub-layer enhances flexibility and crack resistance, allowing the structure to withstand repeated flexing without visible defects.
Solution Approach 2:
The patent employs a composite multi-layer structure combining different materials: a thermoplastic elastomer layer for flexibility, a first gas-barrier sub-layer (e.g., EVOH) for gas barrier properties, and a second gas-barrier sub-layer with distinct properties. This composite structure synergistically maintains gas-barrier performance while preventing cracking through material diversity.
2Ease of operation
If gas-barrier layers are made thinner to improve flexibility, then flexibility increases, but gas transmission rates may increase
Solution Approach 1:
Instead of using a single thick gas-barrier layer, the patent segments it into multiple thinner sub-layers. This segmentation maintains overall flexibility while the multi-layer configuration provides enhanced gas barrier performance through the cumulative effect of multiple barrier interfaces and different material properties.
Solution Approach 2:
The patent uses composite materials where the first gas-barrier sub-layer (e.g., EVOH with specific gas barrier properties) is combined with a second gas-barrier sub-layer having different characteristics. This composite approach achieves low gas transmission rates while maintaining flexibility, as each material compensates for the limitations of the other.
3Duration of action of stationary object
If repeated flexing is withstood by conventional layers, then durability should improve, but cracking and defect visibility increase
Solution Approach 1:
The patent incorporates a thermoplastic elastomer layer between the gas-barrier sub-layers that acts as a cushioning element. This layer absorbs and distributes stress from repeated flexing before it reaches the gas-barrier sub-layers, preventing crack initiation and propagation, thereby extending useful life without visible defects.
Solution Approach 2:
The multi-layer composite structure includes materials with different mechanical properties designed to handle flexing stresses. The elastomeric layers provide flexibility and crack resistance, while the gas-barrier sub-layers maintain integrity through their specific composition, allowing the structure to withstand repeated flexing cycles without developing visible defects.
Data Source
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AI summary
Disclosed is an article of footwear comprising a bladder, wherein the bladder is formed from a multi-layered film comprising a core region, the core region comprising no more than 70 gas-barrier layers formed of a gas-barrier material, wherein the individual average gas barrier layer thicknesses are less than or equal to 0.75 micrometres. Also disclosed are related products and methods.