Aldimine Curing Agents for Bubble-Free Polyurethane Crosslinking
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Solution Overview
Problem
There is a need for new (poly)aldimines that can be used in adhesive compositions, sealants, or coatings, particularly in moisture-crosslinkable polyurethanes, to avoid bubble formation and CO2 release, while providing effective crosslinking.
Innovation Solution
The development of aldimines with specific formulae (I) and (II) that restrict the presence of certain functional groups, allowing for controlled crosslinking without CO2 release, and can be synthesized through reactions between compounds of formulae (III) and (IV).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct crosslinking of isocyanate groups with moisture is used, then crosslinking occurs rapidly, but CO2 is released causing bubble formation
Solution Approach 1:
The patent introduces aldimines as an intermediary substance that mediates between isocyanate groups and moisture. The aldimines first react with isocyanates to form blocked isocyanates, which then slowly release the amine functionality upon contact with moisture, enabling crosslinking without direct CO2-generating reaction between isocyanate and water.
Solution Approach 2:
The patent performs preliminary reaction between amine and aldehyde to form aldimines before the actual crosslinking process. This preliminary action blocks the amine functionality, preventing direct reaction with moisture that would produce CO2, while still enabling subsequent controlled crosslinking through the aldimine-isocyanate-moisture pathway.
2Object-generated harmful factors
If aldimines are used as moisture-activatable curing agents, then bubble formation is avoided, but crosslinking efficiency is reduced
Solution Approach 1:
The patent modifies the chemical structure of aldimines by introducing specific substituents (aromatic groups, heteroatoms, hydrophobic chains) to optimize the balance between stability and reactivity. These parameter changes in molecular structure enhance the crosslinking efficiency while maintaining the bubble-free advantage.
Solution Approach 2:
The patent creates composite curing systems combining aldimines with polyurethane matrices, where the aldimine functionality is integrated into the polymer structure. This composite approach allows the system to benefit from both the bubble-free crosslinking mechanism and enhanced mechanical properties.
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 aldimines provide effective crosslinking in adhesive compositions and sealants, preventing bubble formation and CO2 release, thereby enhancing the performance of moisture-activatable, latent curing agents in polyurethane-based systems.
Implementation Method 1
On contact with water, (poly)aldimines can hydrolyze to the corresponding amines and aldehydes.
Implementation Method 2
(Poly)aldimines are condensation products of primary amines and aldehydes
Data Source
AI summary
The present invention relates to compounds having one of the following formulae (I) and (II):and also to the uses thereof.