Polyurethane Bonded Article Debonding via Surfactant Treatment
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Solution Overview
Problem
There is a need for improved methods to debond bonded articles made of different components, such as shoes, to recycle the different components under mild conditions with low energy consumption, while maintaining high bond strength during regular use.
Innovation Solution
A method involving the use of an aqueous surfactant composition at elevated temperatures to debond bonded articles, where the components are bonded with a polyurethane adhesive having a K value of not more than 100, and the treatment is conducted at temperatures from 60°C to 130°C and a pH of 4 to 12.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesives are used to bond components, then high bond strength is achieved during regular use, but the bonded articles become difficult to recycle and re-use
Solution Approach 1:
The invention changes the chemical parameters of the adhesive system by using polyurethane dispersion adhesives with specific K-values (not more than 100) and controlling molecular weight, allowing the adhesive to maintain strong bonding during use but become susceptible to debonding under specific recycling conditions (aqueous surfactant treatment at elevated temperatures), thus resolving the contradiction between bond strength and recyclability
Solution Approach 2:
The adhesive system transitions from a static strong bond during use to a dynamic state where debonding can be triggered by specific conditions (heat and surfactant treatment). The bond is strong under normal conditions but can be easily reversed when subjected to the recycling process, enabling both high bond strength during use and ease of recycling
2Ease of operation
If debonding is achieved by use of carboxylic acids and salts thereof with microwave irradiation, then non-polyurethane materials can be released from polyurethane materials, but the process requires high energy consumption and complex equipment
Solution Approach 1:
The invention replaces the microwave irradiation system (complex electromagnetic equipment) with a simpler thermal processing system using aqueous surfactant composition at elevated temperatures (60-130°C). This substitutes a complex mechanical/electromagnetic system with a simpler thermal-chemical process, reducing energy consumption and equipment complexity while achieving the same debonding capability
Solution Approach 2:
The invention introduces an aqueous surfactant composition as an intermediary substance that facilitates the debonding process. The surfactant acts as a mediator between the adhesive and the recycling process, enabling easy separation of bonded components without requiring high-energy microwave irradiation or complex chemical treatments
3Ease of operation
If debonding is achieved by use of carboxylic acids and salts thereof, then non-polyurethane materials can be released from polyurethane materials, but the process requires complex chemical treatments
Solution Approach 1:
The invention changes the chemical parameters by using mild aqueous surfactant compositions at controlled pH levels (4-12) and temperatures (60-130°C) instead of strong carboxylic acids. This simplifies the chemical treatment process while maintaining effective debonding capability, reducing process complexity and making the recycling operation easier
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
This method allows for efficient debonding of bonded articles, enabling the separate recycling of components without interfering with the recycling of the thermoplastic polymer materials, while maintaining high bond strength during use.
Implementation Method 1
the at least two components are debonded by treatment with an aqueous surfactant composition at a temperature from 60° C. to 130° C.
Implementation Method 2
treatment with an aqueous surfactant composition at a temperature from 60° C. to 130° C.
Data Source
AI summary
A method is described for debonding a bonded article. The bonded article comprises at least two components which are bonded to one another by means of a polyurethane adhesive selected from aqueous polyurethane dispersion adhesives and polyurethane hotmelt adhesives. At least one of the components is a thermoplastic polyurethane. The components are debonded by treatment with an aqueous surfactant composition at elevated temperatures.