Variable-Pressure Co-Injection Foaming for Adhesive-Free Sole Bonding
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Solution Overview
Problem
Conventional shoe sole structures face issues such as poor durability and easy detachment of the outsole from the midsole due to differences in material properties, and the use of volatile organic compounds in gluing processes poses health and environmental risks.
Innovation Solution
A variable pressure controlled injection method using first and second variable pressure molds with porous layers to form a semi-finished product with a microporous and solidified layer, followed by a co-injection process to bond materials without adhesives, utilizing varying pressures and heating to achieve tight bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gluing processes with volatile organic compounds are used to bond outsole and midsole, then bonding between heterogeneous materials can be achieved, but health and environmental risks increase
Solution Approach 1:
The invention extracts and eliminates the harmful gluing process and volatile organic compounds from the manufacturing system. By using a multi-layer injection molding process that directly bonds heterogeneous materials (such as thermoplastic elastomer and thermoplastic polyurethane) through controlled cooling and phase separation, the method achieves strong bonding without any adhesives, thereby removing the source of health and environmental hazards.
Solution Approach 2:
The invention replaces the chemical bonding mechanism (gluing with volatile organic compounds) with a physical bonding mechanism. Through controlled injection molding with specific temperature and pressure parameters, the process creates a transition layer where materials bond physically through phase separation and molecular entanglement during cooling, eliminating the need for chemical adhesives.
2Reliability
If conventional multi-step surface treatment and gluing processes are used for sole structure, then bonding between outsole and midsole can be achieved, but manufacturing complexity and production time increase
Solution Approach 1:
The invention merges multiple separate manufacturing steps (surface treatment, gluing, drying) into a single integrated injection molding process. By injecting different materials in sequence into the same mold cavity and controlling the cooling process to create a transition layer, the method achieves bonding in one operation, dramatically simplifying the manufacturing process and reducing the number of required devices.
Solution Approach 2:
The invention performs preliminary action by pre-heating the mold cavity and controlling the temperature distribution before material injection. The mold is designed with specific cooling channels that create a controlled temperature gradient, ensuring proper phase separation and bonding during the injection process. This preliminary thermal preparation eliminates the need for subsequent surface treatment and gluing steps.
3Reliability
If conventional gluing processes are used to bond heterogeneous materials, then bonding can be achieved, but production time and manufacturing costs increase
Solution Approach 1:
The invention combines multiple manufacturing operations (molding, bonding, and finishing) into a single injection molding cycle. By injecting materials sequentially and using controlled cooling to create a bonded structure in one operation, the process eliminates the time required for separate gluing and drying steps, significantly reducing total production time.
Solution Approach 2:
The invention maintains continuous useful action throughout the manufacturing process. The injection molding process runs continuously from material injection through cooling to ejection, with bonding occurring automatically during the cooling phase. This eliminates idle time between operations and ensures that every phase of the cycle contributes to the final bonded product.
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 results in a lightweight, durable co-injection product with improved bonding strength between heterogeneous materials, reducing environmental impact and production costs by eliminating the need for adhesives and gluing processes.
Implementation Method 1
a first pressure and a second pressure are different, and the first pressure is a varying pressure
Implementation Method 2
the first foaming material is heated to form a semi-finished injection product
Implementation Method 3
A foaming step is performed, wherein the first variable pressure mold applies a first pressure to the first foaming material, the second variable pressure mold applies a second pressure to the first foaming material, and then the first foaming material is heated
Implementation Method 4
A second foaming material is injected onto the microporous layer of the semi-finished product to obtain a co-injection preform
Data Source
AI summary
A variable pressure controlled injection method, a semi-finished injection product, and a co-injection product manufacturing method are provided. The variable pressure controlled injection method includes providing an injection molding system, injecting a first foaming material, and performing a foaming step. The injection molding system includes a first variable pressure mold and a second variable pressure mold. In the foaming step, the first variable pressure mold and the second variable pressure mold apply a first pressure and a second pressure to the first foaming material respectively, and then the first foaming material is heated to form a semi-finished injection product. The semi-finished injection product includes a microporous layer and a solidified layer. The co-injection product manufacturing method includes injecting a second foaming material onto the semi-finished injection product and heating under a stable internal pressure to complete foam and obtain a co-injection product.