Thermoplastic Shoe Upper Bonding by In-Mold Foamed Midsole
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Solution Overview
Problem
Traditional shoe manufacturing processes are labor-intensive, inefficient, and environmentally harmful, with separate production of sole and upper components requiring human labor, energy-intensive foam molding, and emission of volatile organic compounds (VOCs).
Innovation Solution
A method involving a sole molding unit and supercritical injection foaming (SCIF) to integrate the production of a shoe's upper and midsole using a thermoplastic polymer material, forming a direct material-bonded connection without additional adhesives, reducing human labor and VOC emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional separate production methods are used for sole and upper, then manufacturing flexibility is maintained, but production efficiency decreases and labor requirements increase
Solution Approach 1:
The patent combines the production of upper and sole into a single integrated process. The upper assembly is inserted into a sole molding unit, and both components are produced and bonded together in one operation, eliminating the need for separate production lines and reducing overall process complexity despite increasing integration.
Solution Approach 2:
The sole molding unit is designed to perform multiple functions: it molds the sole, receives and positions the upper assembly, and provides bonding through direct contact with the upper material. This multi-functional approach consolidates what were previously separate operations into a single universal device.
2Ease of manufacture
If classic foam molding is used, then sole production is achieved, but energy consumption increases due to mold heating
Solution Approach 1:
The upper material itself serves as the heating source for the sole molding process. The thermoplastic upper material is heated and molded directly onto the sole, eliminating the need for external mold heating systems and reducing energy consumption while maintaining sole production capability.
3Strength
If traditional adhesive bonding is used, then connection between upper and sole is achieved, but additional materials and environmental harm are introduced
Solution Approach 1:
The patent converts the thermoplastic properties of the upper material from a potential source of emissions into a bonding mechanism. By heating and molding the upper material directly onto the sole, the process creates a strong mechanical and thermal bond without requiring separate adhesives, thereby eliminating VOC emissions while maintaining connection strength.
4Productivity
If manual operations are used for midsole production, then flexibility is maintained, but productivity decreases due to labor intensity
Solution Approach 1:
The patent merges midsole production with upper assembly production in a single integrated operation. The upper assembly is inserted into the sole molding unit, and both components are produced and bonded simultaneously, eliminating manual transfer operations and increasing automation capability while improving productivity.
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 method enhances production efficiency, reduces resource demand, minimizes waste, and lowers environmental impact while providing a stronger, more durable shoe connection.
Implementation Method 1
The midsole polymer composition comprises a molten thermoplastic polymer midsole material having a melting temperature which is equal to or higher than the melting temperature of the thermoplastic polymer upper material
Implementation Method 2
foaming the molten thermoplastic polymer midsole material to establish a direct material-bonded, in particular fused, connection between the upper and the foamed midsole
Implementation Method 3
a direct material-bonded, in particular fused, connection between the upper and the foamed midsole is established
Data Source
AI summary
A shoe, a shoe production system and a method for producing a shoe including the steps: a. providing an upper assembly (2), wherein the upper assembly includes an upper (3) being mounted on a carrier (4), wherein the upper (3) includes a bottom section (5) being made from a thermoplastic polymer upper material; b. providing a sole molding unit (6), wherein the sole molding unit defines a cavity; c. inserting the upper assembly (2) at least partially into the cavity; introducing a midsole polymer composition comprising a molten thermoplastic polymer midsole material which has a melting temperature being equal or higher than the melting temperature of the thermoplastic polymer upper material into the cavity and foaming the molten thermoplastic polymer midsole material inside the cavity to provide a foamed midsole and to establish a material-bonded connection between the upper (3) and the foamed midsole (8).