Single-Sided Footwear Gluing with Polyisocyanate Solvent
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Solution Overview
Problem
The footwear industry faces high labor costs, complicated gluing processes, and low production efficiency due to the traditional double-sided gluing process, and existing single-sided gluing methods fail to achieve adequate bond strength, heat resistance, and hydrolysis resistance.
Innovation Solution
A method involving single-sided gluing using a cleaning agent with a polar organic solvent and a polyisocyanate, where the solvent has a boiling point of no more than 135 °C and is not isocyanate-reactive, and the polyisocyanate has a specific formula and weight percentage, applied to substrates to enhance bonding and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If double-sided gluing process is used, then bond strength is improved, but labor cost increases and production efficiency decreases
Solution Approach 1:
The invention extracts and eliminates one of the two gluing sides from the traditional double-sided gluing process, implementing single-sided gluing where adhesive is applied only to the shoe upper rather than both the upper and sole. This reduction in gluing operations directly decreases labor requirements and improves production efficiency while maintaining adequate bond strength through optimized adhesive formulation and substrate treatment.
2Productivity
If single-sided gluing process is used, then production efficiency is improved, but bond strength becomes insufficient
Solution Approach 1:
The invention changes the chemical parameters of the adhesive system by formulating a specific adhesive composition containing polyurethane resin, polyamide resin, and isocyanate in controlled proportions, along with optimizing substrate treatment parameters using cleaning agents with specific solvent compositions. These parameter optimizations enable single-sided gluing to achieve bond strength comparable to or exceeding traditional double-sided gluing.
Solution Approach 2:
The invention employs composite adhesive materials combining multiple resin components (polyurethane and polyamide) with crosslinking agents (isocyanate) to create a multi-functional adhesive system that provides enhanced bond strength, flexibility, and resistance properties, allowing single-sided application to deliver sufficient bonding performance.
3Manufacturing precision
If traditional cleaning agents are used, then substrate preparation is improved, but adhesive performance deteriorates due to contamination
Solution Approach 1:
The invention changes the chemical composition parameters of the cleaning agent by specifying a solvent system comprising ester compounds with controlled carbon chain lengths and ratios, replacing traditional cleaner formulations. This optimized cleaning agent removes contaminants without leaving residues that would interfere with adhesive bonding, thereby maintaining both substrate preparation quality and adhesive performance.
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 produces bonded articles with good initial and final bond strength, heat resistance, and hydrolysis resistance, improving mechanical properties and production efficiency while reducing labor costs.
Implementation Method 1
the polyisocyanate has a general formula R(NCO)n, wherein R is one or more of the following: an aliphatic hydrocarbon group having 2 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms, and an araliphatic hydrocarbon group having 8 to 15 carbon atoms
Implementation Method 2
the polar organic solvent has a boiling point of no more than 135 °C and is not isocyanate-reactive
Data Source
Figure 1~2
AI summary
This invention relates to a method for preparing a bonded article by conducting single-sided gluing, the bonded article prepared by said method, and the use of the bonded article in the production of footwear. The method comprises the steps of: a. applying a cleaning agent to at least one surface of a first substrate, and drying the surface of the first substrate to which the cleaning agent is applied; b. applying an adhesive to at least one surface of a second substrate, and drying the surface of the second substrate to which the adhesive is applied; and c. contacting the surface of the first substrate treated in step a with the surface of the second substrate treated in step b to obtain the bonded article; wherein the cleaning agent comprises a polar organic solvent and a polyisocyanate; the polar organic solvent has a boiling point of no more than 135 °C and is not isocyanate-reactive; wherein the polyisocyanate has an isocyanate group weight of from 0.005 wt% to 6 wt%, based on the weight of the cleaning agent.