Thermoplastic Elastomer Outsole Viscosity Control for Shoe Molding
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Solution Overview
Problem
Conventional shoe sole production methods face challenges in achieving high-quality products due to excessive fluidity of EVA during hot-pressing, leading to inadequate shaping of the outsole, which affects the overall quality and efficiency of shoe production.
Innovation Solution
A shoe design incorporating a midsole made of polymer foam and an outsole formed from a thermoplastic elastomer with specific complex viscosity ranges (10 kPa·s ≤ η140 ≤ 300 kPa·s and η180 ≤ 100 kPa·s) that are heat-fused together, ensuring accurate molding and reduced fluidity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EVA is heated to high temperature during hot-pressing to improve fluidity for outsole shaping, then the outsole can better reflect the mold shape, but the EVA flows out of the molding space causing quality deterioration
Solution Approach 1:
The patent changes the material parameter from conventional EVA to a specific thermoplastic elastomer with controlled viscosity characteristics. The material has a viscosity of 50-500 Pa·s at 140°C and 10-100 Pa·s at 180°C, which provides optimal fluidity for molding while preventing excessive flow. This parameter change resolves the contradiction by enabling precise shaping without material overflow.
2Productivity
If a single forming mold is used to produce both midsole and outsole simultaneously to improve productivity, then production efficiency increases, but the process becomes more complex and requires precise control of material properties
Solution Approach 1:
The patent merges the production of midsole and outsole into a single simultaneous forming process using one forming mold. The thermoplastic elastomer material is placed in the mold, heated to melt, and then pressed to form both the midsole and outsole components in one operation. This merging eliminates the need for separate production and bonding steps, significantly improving productivity while the controlled material properties simplify the overall process control.
3Ease of manufacture
If conventional EVA is used for outsole to maintain material consistency with midsole, then production process is simplified, but the outsole lacks sufficient grip performance and wear resistance
Solution Approach 1:
The patent applies local quality by using different materials for different functional requirements. The midsole uses polymer foam for cushioning, while the outsole uses thermoplastic elastomer for grip and wear resistance. The thermoplastic elastomer material provides the necessary friction coefficients and durability for ground contact, while the polymer foam provides shock absorption. This differentiation optimizes both manufacturing ease and product reliability.
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
This approach allows for efficient and high-quality shoe production by preventing excessive fluidity of the thermoplastic elastomer, enabling precise shaping and firm fusion of the midsole and outsole, resulting in improved grip, cushioning, and wear resistance.
Implementation Method 1
the EVA for the outsole is required to exhibit high fluidity at the heating temperature of the hot-pressing
Implementation Method 2
hot-pressed
Implementation Method 3
the outsole and the midsole are heat-fused to each other
Data Source
AI summary
Provided in the present invention is a shoe that can be of high quality and easily produced, by forming an outsole with a thermoplastic elastomer showing specific complex viscosities at 140° C. and 180° C.