EVA Footwear Sole Composition Durability Softness Trade-off
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Solution Overview
Problem
Current combined sole materials in footwear lack durability and longevity, particularly when made from softer compounds, compromising their ability to provide both softness and durability, and existing solutions that enhance cushioning increase cost, complexity, and weight.
Innovation Solution
A proprietary composition of EVA, EPDM rubber, polyolefin elastomer, filler agents, and bridging agents is used to create a sole material that is durable, lightweight, and abrasion-resistant, with a process involving weighing, heating, forming pellets, injecting into a mold, and controlled cooling to achieve a Shore hardness of 40-50 C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If softer compounds or materials are used in combined soles to provide better shock absorption, comfort and cushioning, then the softness and cushioning properties are improved, but the durability and longevity of the combined soles are reduced
Solution Approach 1:
The patent uses a composite material system consisting of EVA copolymer base resin combined with specific plasticizers (adipic acid and/or azelaic acid) and antioxidants. This composite formulation creates a material that simultaneously achieves softness (Shore A 40-60) for comfort and cushioning while maintaining durability through the synergistic effects of the compound components, particularly the antioxidants that prevent degradation of the softened material.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the EVA material by controlling the vinyl acetate content (10-40%), adjusting plasticizer quantities (5-30 phr), and optimizing antioxidant levels. These parameter changes enable the material to achieve the desired balance between softness for comfort and structural integrity for durability, with Shore A hardness specifically controlled in the 40-60 range.
2Ease of operation
If gel and/or air compartments are incorporated to create desired shock absorption and cushioning properties, then the comfort and softness are improved, but the cost, complexity and weight of existing soles are increased
Solution Approach 1:
Instead of adding separate gel or air compartments, the patent achieves localized cushioning properties throughout the entire sole material by uniformly distributing plasticizers and antioxidants within the EVA matrix. This creates consistent shock absorption and comfort properties across the sole structure without adding discrete components, thereby avoiding increased complexity and weight while maintaining the desired cushioning performance.
Solution Approach 2:
The patent makes the base EVA material itself multi-functional by formulating it to simultaneously provide structural support, shock absorption, cushioning, and durability. The single compound system performs all these functions that would otherwise require separate gel compartments, air pockets, or additional layers, thereby simplifying the overall sole construction while achieving the desired comfort and protective properties.
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 resulting sole material exhibits high durability, abrasion resistance, and superior cushioning, combining softness and support in a single material, unattainable with previous technologies, while maintaining a lightweight and stable structure.
Implementation Method 1
a process involving weighing, heating, forming pellets, injecting into a mold, and controlled cooling to achieve a Shore hardness of 40-50 C
Implementation Method 2
EVA is lightweight foam based cushioning
Implementation Method 3
bridging agents
Data Source
AI summary
This disclosure provides for a new composition of matter, said composition of matter featuring a previously unattainable combination of softness, resiliency, durability and support in a sole material for footwear, as well as a process of manufacturing said composition of matter.