Thermoplastic Polyurethane Foam Midsole Injection Molding
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Solution Overview
Problem
The existing manufacturing process for thermoplastic polyurethane foam materials used in athletic shoe midsoles is complex, energy-intensive, labor-intensive, and prone to inconsistencies and safety concerns, making it unfavorable for automation and rapid production.
Innovation Solution
A thermoplastic polyurethane foam material comprising diphenylmethane diisocyanate, polytetramethylene ether glycol, 1,4-butanediol, a nucleating agent, and a specific thinning agent, which enhances solubility of supercritical nitrogen, reducing dynamic viscosity and improving foaming effects, is used in conjunction with a manufacturing method involving mixing, polymerization, granulation, and foaming steps to produce a lightweight, elastic midsole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the traditional bead foam supercritical foaming method is used, then foam materials can be produced with good elasticity and insulation, but the manufacturing process becomes complicated and unfavorable for automation
Solution Approach 1:
The patent applies preliminary action by pre-mixing all raw materials (polyol, isocyanate, catalyst, blowing agent, and the specific thinning agent of formula I) before injection molding. This pre-mixing step ensures homogeneous distribution of components, eliminating the need for complex post-processing and bead foam assembly operations, thereby simplifying the manufacturing process while maintaining foam quality
Solution Approach 2:
The patent extracts and eliminates the complicated bead foam manufacturing steps from the process. Instead of producing beads separately and then assembling them, the invention directly injects and molds the foam material in one step, removing the intermediate bead production and assembly operations that complicate the manufacturing process
2Quantity of substance
If the bead foam supercritical foaming method is used, then foam materials can be produced, but energy consumption increases and labor intensity rises
Solution Approach 1:
The patent merges multiple separate operations (mixing, injection, foaming, and molding) into a single integrated injection molding process. All raw materials are pre-mixed and then injected directly into the mold where foaming and molding occur simultaneously, eliminating the need for separate bead production, drying, and assembly steps, thereby significantly reducing energy consumption and labor intensity
Solution Approach 2:
The foam material performs self-service by automatically expanding and filling the mold cavity during the injection process. The blowing agent naturally expands the polymer matrix without requiring external foaming equipment or additional energy input, making the foaming process self-sustaining and energy-efficient
3Quantity of substance
If the traditional manufacturing process is used, then foam materials can be produced, but product dimension consistency deteriorates
Solution Approach 1:
The patent applies local quality by ensuring homogeneous distribution of the thinning agent and other additives throughout the polymer matrix through pre-mixing. This uniform distribution guarantees consistent local properties throughout the final product, leading to uniform foaming behavior and consistent dimensional accuracy across all produced parts
Solution Approach 2:
The patent changes the chemical composition parameters by introducing the specific thinning agent of formula I with controlled molecular weight and hydroxyl value. This parameter change improves the flow and foaming characteristics of the material, enabling more precise control over cell structure and final product dimensions, thereby enhancing manufacturing precision
4Quantity of substance
If the bead foam supercritical foaming method is used, then foam materials can be produced, but the process becomes labor-intensive and involves bulky equipment
Solution Approach 1:
The patent replaces complex mechanical bead handling and assembly systems with a chemical injection molding system. The foam material is delivered as a injectable mixture that automatically expands in the mold, eliminating the need for mechanical bead conveyance, positioning, and assembly equipment, thereby simplifying operations and reducing equipment bulk
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 solution results in a lightweight midsole with enhanced elasticity and reduced density, improving comfort and athletic performance while simplifying the manufacturing process and reducing energy consumption and material inconsistencies.
Implementation Method 1
having a solubility parameter of 19.5 to 23.0 (J/cm3)0.5, so as to enhance solubility of supercritical nitrogen in the thermoplastic polyurethane foam material
Implementation Method 2
enhance solubility of supercritical nitrogen
Implementation Method 3
a foaming step is performed, wherein the plurality of foaming particles undergo foaming to form the thermoplastic polyurethane foam material
Data Source
AI summary
A thermoplastic polyurethane foam material, a midsole of athletic shoe and a manufacturing method of a foam material are provided. The thermoplastic polyurethane foam material includes a diphenylmethane diisocyanate, a polytetramethylene ether glycol, a 1,4-butanediol, a nucleating agent and a thinning agent. The thinning agent has a structure represented by formula (I), of which each symbol is defined in the specification.