Latent Amine Catalyst for Polythioether Sealant Working Time
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Solution Overview
Problem
Thiol-terminated polythioether-based sealants in aerospace applications face challenges with short working times and rapid curing, which limits their effectiveness in meeting demanding performance requirements such as adhesion, tensile strength, elongation, and high temperature stability.
Innovation Solution
The use of epoxy-cured thiol-terminated polythioether compositions incorporating a latent amine catalyst, either an imidazole inclusion catalyst, an imidazole-epoxy adduct, or a combination thereof, extends the working time while enabling rapid curing, thus addressing the limitations of existing sealants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If typical polythioether-based sealants are used, then rapid curing is achieved, but working time is limited to less than 12 hours
Solution Approach 1:
The patent applies preliminary action by incorporating a latent amine catalyst into the sealant composition before application. This catalyst remains dormant during storage and initial application, then activates after a predetermined period to initiate rapid curing. This allows the sealant to maintain extended working time while ultimately achieving fast cure rates, resolving the contradiction between working time and cure speed.
2Duration of action of moving object
If extended working time is achieved through latent catalysts, then cure rate may be reduced, but rapid curing is still required at the end of working time
Solution Approach 1:
The patent employs dynamics by using a latent amine catalyst that transitions from an inactive state during the working period to an active state after the desired working time has elapsed. This dynamic behavior allows the system to provide extended working time initially, then automatically switch to rapid curing mode, simultaneously achieving both extended working time and fast final cure rate.
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 described compositions provide extended working time and fast cure rates, ensuring the sealants meet the stringent performance criteria for aerospace applications, including enhanced adhesion, tensile strength, and fuel resistance across a wide temperature range.
Implementation Method 1
epoxy-cured, thiol-terminated polythioether-based sealants that include a latent amine catalyst selected from an imidazole inclusion catalyst, an imidazole-epoxy adduct, and a combination thereof
Data Source
Figure 1
AI summary
Thiol-terminated polythioether compositions and sealants prepared using the thiol-terminated polythioether compositions that exhibit extended working time and that rapidly cures at room temperature at the end of the working time are disclosed.