Thermally Debondable Primer Composition for Adhesive Disassembly
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Solution Overview
Problem
Existing adhesive bonds are difficult to disassemble without damaging the substrates, as mechanical removal methods are inefficient and chemical or thermal methods can be time-consuming and risk damaging the substrates.
Innovation Solution
A thermally debondable primer composition comprising polyether urethane methacrylate resin, (meth)acrylate monomers, thermally expandable thermoplastic microspheres, and a photoinitiator, which is cured via photo-curing and can be easily debonded by applying heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive bonds are designed to be strong for withstanding drop or impact events and wide temperature ranges, then adhesion strength is improved, but difficulty in disassembly increases
Solution Approach 1:
The adhesive system is segmented into two distinct layers: a permanent adhesive layer that provides strong bonding, and a removable primer layer that facilitates disassembly. This segmentation allows each layer to perform its specific function independently - the permanent adhesive maintains strong adhesion while the removable primer enables easy removal through thermal expansion
Solution Approach 2:
The removable primer layer acts as an intermediary between the substrate and the permanent adhesive layer. This intermediate layer can be selectively removed through thermal expansion of microspheres, allowing the permanent adhesive to remain intact while enabling disassembly of the bonded structure
2Ease of operation
If mechanical processes are used to remove adhesive, then disassembly is achieved, but substrate surfaces are damaged
Solution Approach 1:
The removal function is extracted from the permanent adhesive layer and transferred to a separate removable primer layer. This allows the permanent adhesive to remain on the substrate without damage, while the primer layer is removed through controlled thermal expansion, preventing substrate damage that would occur with mechanical removal methods
3Ease of operation
If chemicals or high temperature are applied to debond, then adhesive bonding is disrupted, but substrates are damaged and process becomes time-consuming
Solution Approach 1:
The thermal expansion property is localized specifically to the removable primer layer through the incorporation of thermally expandable microspheres. This localized quality ensures that only the primer layer undergoes significant volume expansion and debonding when heated, while the permanent adhesive layer and substrates remain unaffected and undamaged
Solution Approach 2:
The system utilizes parameter changes in the form of thermally expandable microspheres that undergo a dramatic volume increase (up to 200 times) when exposed to heat. This parameter change is confined to the removable primer layer, enabling controlled debonding without exposing the substrates to the harsh conditions required for traditional chemical or thermal debonding methods
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 primer composition effectively weakens the bond strength by at least 50% upon heat application, allowing for efficient debonding while maintaining optimal adhesion and mechanical properties, as demonstrated by the tensile lap shear strength tests.
Implementation Method 1
the thermally debondable primer composition is cured via photo-curing
Implementation Method 2
thermally expandable thermoplastic microspheres
Data Source
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Figure 5
AI summary
The present invention relates to a thermally debondable primer composition comprising a polyether urethane methacrylate resin; two or more (meth)acrylate monomers; thermally expandable thermoplastic microspheres; and one or more photoinitiator.