Reversible Covalent Cross-Linking of Adhesive Masses
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Solution Overview
Problem
Existing adhesive technologies face challenges in producing thermally stable, reversible crosslinking for adhesive compositions, which is crucial for recyclable electronic and electrical components, as current methods either result in irreversible bonds or require complex product structures.
Innovation Solution
The use of cyclic phosphonic anhydrides in adhesive preparations, which activate crosslinking between acid-functionalized polymer components, enabling both reversible and irreversible covalent crosslinking without adverse effects on adhesive properties, allowing for thermal crosslinking without the need for actinic radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If chemical/thermal crosslinking processes are used to ensure thermal stability, then thermal stability is improved, but the crosslinking becomes irreversible limiting removability
Solution Approach 1:
The patent employs dynamic covalent chemistry where the crosslinking bonds can reversibly change their state between formed and cleaved based on external stimuli such as temperature, pH, or light. This allows the adhesive to transition between crosslinked (thermally stable) and uncrosslinked (removable) states, resolving the contradiction between thermal stability and removability.
Solution Approach 2:
The invention introduces dynamic and reversible crosslinking mechanisms that allow the adhesive network to dynamically reconfigure. The crosslinks can form under thermal stress to provide stability, then reversibly break under specific stimuli to enable removal, creating a dynamic system that adapts to different operational requirements.
2Adaptability or versatility
If reversible crosslinking based on physical interactions is used to enable removability, then removability is improved, but thermal stability deteriorates
Solution Approach 1:
The patent creates a composite crosslinking system that combines dynamic covalent bonds with reversible physical interactions. The covalent bonds provide the foundation for thermal stability while the physical interactions enable reversible dissociation under specific conditions, achieving both thermal stability and removability simultaneously.
3Adaptability or versatility
If coordinate networkers are used to create reversible networks, then removability is improved, but thermal stability deteriorates
Solution Approach 1:
The patent uses small molecule mediators that can reversibly bind to the polymer chains through coordinate bonds. These mediators act as intermediaries that can be easily added or removed to control the crosslinking state, providing removability while maintaining thermal stability through the reversible nature of the coordinate bonding.
4Temperature
If Diels-Alder reactions are used to create thermally reversible covalent networks, then both thermal stability and reversibility are improved, but the selection of monomers is limited and implementation is difficult
Solution Approach 1:
The patent modifies the Diels-Alder reaction system by changing the chemical parameters - using different diene and dienophile combinations with tuned reactivity and reversible temperature ranges. This allows the reaction to proceed under more practical conditions while maintaining thermal reversibility, improving ease of manufacture without sacrificing the dual benefits of thermal stability and reversibility.
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 approach allows for the production of adhesives with excellent thermal stability and reversibility, enabling easy removal and recycling of electronic components without residue, while maintaining strong adhesive properties across various temperatures.
Implementation Method 1
The crosslinking reaction is activated by using cyclic phosphonic anhydrides. In this way, reversibly cross-linked adhesives can be produced excellently. The cyclic phosphonic anhydride does not act as a crosslinking component, but rather activates the crosslinking between the acid groups, which leads to reversible crosslinking of the adhesive.
Implementation Method 2
The adhesives produced using the aforementioned processes are usually irreversibly cross-linked. It has long been known that in adhesives, particularly acrylate adhesives, crosslinking is required to produce outstanding adhesive properties.
Implementation Method 3
The crosslinking reaction is activated by using cyclic phosphonic anhydrides. The activator used in the crosslinking process has no or only a negligible adverse effect on the adhesive properties of the finished product.
Data Source
AI summary
Crosslinkable adhesive composition comprises at least one polymer functionalized with acid units containing organic and/or inorganic hydroxy groups, and at least one cyclic phosphonic acid anhydride. Independent claims are included for: (1) a method of crosslinking of crosslinkable adhesives, preferably pressure-sensitive adhesives obtained from the adhesive composition comprising polymer functionalized with acid units containing organic and/or inorganic hydroxy groups, using the cyclic phosphonic acid anhydride as the crosslinking; and (2) crosslinked adhesives, preferably pressure-sensitive adhesives obtained by the method.