Thermally Debondable Polyurethane Adhesive for Substrate-Safe Disassembly
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Solution Overview
Problem
Existing adhesive compositions used in e-mobility components are difficult to debond without damaging the substrates, especially in applications requiring disassembly, and current debonding methods like mechanical or chemical processes can be time-consuming and substrate-damaging.
Innovation Solution
A thermally debondable two-component polyurethane adhesive composition comprising polymeric polyols and thermally expandable thermoplastic microspheres, mixed in a specific ratio, which weakens bonds upon heat application, allowing easy disassembly without damaging substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong adhesive bonds are used to maintain adhesion during drop or impact events and across wide operating temperatures, then adhesion strength and reliability are improved, but the ability to disassemble components without damaging substrates deteriorates
Solution Approach 1:
The adhesive composition changes its bonding parameters in response to temperature changes. At normal operating temperatures, the adhesive maintains strong bonding through its polymeric structure. When exposed to elevated temperatures (above the glass transition temperature of the thermoplastic polymer), the adhesive softens and reduces bond strength, enabling easy disassembly without damaging substrates.
Solution Approach 2:
The adhesive system transitions from a static strong bond to a dynamic condition where bond strength can be modulated by temperature. The thermoplastic polymer component provides this dynamic behavior, allowing the adhesive to adapt between strong bonding during operation and easy release during maintenance or recycling.
2Ease of repair
If mechanical processes like sand blasting or wire brushing are used to remove adhesive, then adhesive removal is achieved, but substrate surfaces are corrupted and damaged
Solution Approach 1:
The patent replaces mechanical removal processes (sand blasting, wire brushing) with a thermal process. By applying heat to raise the temperature above the glass transition temperature of the thermoplastic polymer, the adhesive softens and can be easily removed without mechanical contact with the substrate, eliminating substrate damage.
3Ease of repair
If aggressive chemicals or high temperature are applied to debond adhesive, then adhesive bonding is disrupted, but substrates are damaged and rendered unsuitable for subsequent applications
Solution Approach 1:
The adhesive is formulated with a thermoplastic polymer having a specific glass transition temperature that allows debonding at moderate temperatures. This temperature parameter is carefully selected to be high enough to avoid substrate damage but low enough to enable effective debonding, replacing the need for aggressive chemicals or extreme temperatures.
4Ease of repair
If high temperature is applied to disrupt bonding at the adhesive-substrate interface, then thermal debonding is achieved, but substrates may be damaged
Solution Approach 1:
The thermoplastic polymer's glass transition temperature serves as a controlled parameter that dictates the debonding temperature. By selecting a polymer with an appropriate Tg, the debonding temperature is optimized to be sufficiently high for effective bond disruption but sufficiently low to prevent substrate heat damage, achieving a balance between debonding capability and substrate protection.
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 composition provides effective debonding with reduced bond strength after heat activation, maintaining adhesion and mechanical properties, and protecting substrates from heat damage during debonding.
Implementation Method 1
thermally expandable thermoplastic microspheres... which weakens bonds upon heat application
Implementation Method 2
thermally expandable thermoplastic microspheres... allowing easy disassembly without damaging substrates
Data Source
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AI summary
The present invention relates to use a thermally debondable two-component polyurethane adhesive composition or cured product according to the present invention in a bonded structure, wherein the bonded structures are for example e-mobility related components.