Dual Curable Thiol-Ene Sealant for Aerospace Applications
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Solution Overview
Problem
Existing aerospace sealants face challenges in achieving a balance between long application time and short curing time, and they often require specific conditions for curing, such as light exposure, which can be inconsistent or incomplete.
Innovation Solution
A curable sealant composition comprising a polythiol, an unsaturated compound with multiple carbon-carbon double or triple bonds, a photoinitiator for photochemical curing, and an organic hydroperoxide for backup curing under ambient conditions, providing a cure-on-demand feature and ensuring complete curing even in unexposed areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a photoinitiator system is used for curing the sealant, then rapid curing can be achieved on demand, but the application time is limited by the requirement for light exposure and the curing may be incomplete in unexposed areas
Solution Approach 1:
The patent incorporates both a photoinitiator and a hydroperoxide initiator with a metal chelate catalyst in the sealant composition before application. This preliminary preparation of dual curing systems allows the material to be applied in the dark or in low-light conditions without premature curing, then cured rapidly on demand in exposed areas while the hydroperoxide system provides backup curing capability in unexposed areas, ensuring complete and reliable curing throughout.
Solution Approach 2:
The patent uses a hydroperoxide initiator that can cure the thiol-ene composition through redox mechanisms at ambient temperatures. This changes the curing parameter from requiring light activation alone to enabling both light-initiated and thermal/initiator-driven curing pathways, allowing complete curing in areas where light cannot reach while maintaining rapid cure capability in exposed areas.
2Productivity
If the sealant requires light exposure for curing, then rapid curing is achieved, but the application process becomes complex and requires consistent light exposure conditions
Solution Approach 1:
The patent creates a sealant composition with multi-functional curing capability by incorporating both photoinitiator and hydroperoxide initiator systems. This allows the same sealant to be cured through multiple pathways (light exposure, ambient temperature with metal chelate catalyst, or combination), simplifying the overall application process by eliminating the need for specialized equipment or strict light exposure conditions while maintaining high curing efficiency.
3Device complexity
If a single curing mechanism is used, then the formulation is simple, but the curing may be incomplete in areas not exposed to light
Solution Approach 1:
The patent pre-configures the sealant with both photoinitiator and hydroperoxide initiator systems along with a metal chelate catalyst before application. This preliminary preparation ensures that both curing pathways are available from the start, allowing the sealant to be applied without concern for light exposure conditions, then cured completely and reliably whether in exposed or unexposed areas.
Solution Approach 2:
The patent creates a composite curing system by combining thiol-ene monomers/oligomers with both photoinitiator and hydroperoxide initiator components. This composite formulation integrates multiple curing mechanisms into a single unified material system, maintaining formulation simplicity while ensuring complete and reliable curing throughout all areas of the application, regardless of light exposure.
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 allows for a long application time with the option for rapid curing on demand, maintaining usability and ensuring thorough curing without reliance on consistent light exposure, suitable for aerospace applications.
Implementation Method 1
a photoinitiator suitable for photochemically curing the composition by generating free radicals
Implementation Method 2
The second initiator is a hydroperoxide suitable for curing the composition, for example, under ambient conditions
Data Source
Figure 1
AI summary
A dual curable thiol-ene composition comprising a polythiol, an unsaturated compound, a photoinitiator, an organic hydroperoxide (thermal initiator) and optionally a nitrogen-containing base, such as e.g. an N-heterocyclic compound (together with the organic hydroperoxide a redox initiator system). A cross-linked polymer prepared therefrom. A method of making such a polymer. A cured sealant comprising such a polymer. The sealant is preferably for use in aerospace.