TPU Hot-Melt Adhesive for Rubber-EVA Shoe Sole Bonding
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Solution Overview
Problem
Existing hot-melt adhesives for bonding rubber shoe outsoles and EVA midsoles require multiple solvent-based processes, which are time-consuming, labor-intensive, and harmful to human health and the environment, while existing modified thermoplastic polyurethane adhesives lack sufficient adhesion to low-polar materials like rubber and EVA.
Innovation Solution
A thermoplastic polyurethane hot-melt adhesive composed of a reaction product of isocyanate, polyol containing 10-40 wt% polyolefin polyol with ethylenically unsaturated groups, and a diol-based chain extender, which is environmentally friendly and provides good adhesion to low-polar materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solvent-based primers and polyurethane glue are used for bonding rubber outsoles and EVA midsoles, then adhesion strength is improved, but production time increases and environmental harm increases
Solution Approach 1:
The patent changes the chemical parameters of the adhesive by using thermoplastic polyurethane with specific polyol components (polyester polyol, polyether polyol, or polycarbonate polyol) and controlling the molecular weight and hydroxyl value ranges, enabling solvent-free bonding that maintains adhesion strength while reducing production time
Solution Approach 2:
The patent extracts and eliminates the harmful solvent component from the adhesive system, achieving bonding without requiring solvent-based primers and glue, thereby removing the need for oven drying steps and reducing production time while maintaining environmental friendliness
2Strength
If solvent-based primers and polyurethane glue are used for bonding rubber outsoles and EVA midsoles, then adhesion strength is improved, but environmental harm increases
Solution Approach 1:
The patent converts the harmful solvent-based adhesive system into a beneficial solvent-free thermoplastic polyurethane adhesive, where the polyol components (polyester, polyether, or polycarbonate) provide the necessary adhesion to low-polar materials like rubber and EVA without requiring harmful solvents, thereby eliminating environmental harm while maintaining bonding strength
Solution Approach 2:
The patent changes the chemical composition parameters by specifying polyol content (10-40 wt%), polyolefin polyol content (10-40 wt%), and molecular weight ranges, creating an environmentally friendly adhesive that achieves good adhesion to low-polar materials without harmful solvents
3Ease of manufacture
If conventional thermoplastic polyurethane adhesive is used for bonding low-polar materials like rubber and EVA, then processing simplicity is improved, but adhesion strength deteriorates
Solution Approach 1:
The patent creates a composite thermoplastic polyurethane adhesive system combining multiple polyol components (polyester polyol, polyether polyol, or polycarbonate polyol) with specific polyolefin polyol content (10-40 wt%), achieving both processing simplicity and enhanced adhesion strength to low-polar materials through the synergistic effect of the composite material
Solution Approach 2:
The patent optimizes the chemical parameters by controlling polyol content (10-40 wt%), polyolefin polyol content (10-40 wt%), hydroxyl value (40-150 mg KOH/g), and molecular weight ranges, enabling the adhesive to maintain good adhesion strength to low-polar materials while preserving processing simplicity
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 adhesive achieves strong bonding between rubber outsoles and EVA midsoles with improved adhesion and processing efficiency, reducing production time and eliminating the need for harmful solvents, while maintaining environmental friendliness.
Implementation Method 1
A thermoplastic polyurethane hot-melt adhesive composed of a reaction product of isocyanate, polyol containing 10-40 wt% polyolefin polyol with ethylenically unsaturated groups, and a diol-based chain extender, which is environmentally friendly and provides good adhesion to low-polar materials
Data Source
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AI summary
The present invention relates to a thermoplastic polyurethane hot-melt adhesive comprising: a reaction product of (a) an isocyanate; (b) a polyol comprising at least 5 wt% of a polyolefin polyol based on the total weight of the polyol; and (c) a chain extender, wherein the polyolefin polyol comprises an ethylenically unsaturated group. The present invention also relates to a method of preparing a shoe sole assembly using the thermoplastic polyurethane hot-melt adhesive and the use of the thermoplastic polyurethane hot-melt adhesive in the preparation of the shoe sole assembly.