Polythioether Sealant Composition for Aerospace Fuel Resistance
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Solution Overview
Problem
Aerospace sealant compositions require properties such as fuel resistance, low temperature flexibility, and rapid curing, while also needing to be sprayable and free of solvents, which existing technologies have not adequately addressed.
Innovation Solution
Development of multi-component sealant compositions comprising isocyanate functional polythioether-polyurethane and amine/hydroxy-functional polythioether, which are substantially free of volatile organic compounds, sprayable, and fuel resistant, utilizing specific polymer structures and reaction methods to achieve these properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealant compositions use thiol-terminated sulfur-containing compounds for fuel resistance, then fuel resistance is improved, but the compositions become difficult to spray and require solvents
Solution Approach 1:
The patent changes the chemical parameters of the sealant composition by using polythioether polymers with specific molecular weights (5,000-50,000) and controlled functionality (2-4 thiol groups per molecule). These parameter adjustments enable the composition to be sprayable without solvents while maintaining fuel resistance, resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
The patent creates a composite sealant system combining polythioether polymers with specific curing agents (amines or hydroxyl compounds) in controlled ratios. This composite approach allows the formulation to achieve both sprayability and fuel resistance by balancing the properties of different components, eliminating the need for solvents while maintaining operational ease.
2Object-generated harmful factors
If sealant compositions are made solvent-free, then environmental compliance is improved, but application viscosity increases making spraying difficult
Solution Approach 1:
The patent adjusts the viscosity parameter by selecting polythioethers with specific molecular weights and incorporating plasticizers or adjusting the polymer structure. This enables the solvent-free composition to maintain appropriate flow characteristics for spray application while eliminating volatile organic compounds, resolving the contradiction between environmental compliance and ease of operation.
3Productivity
If sealant compositions cure rapidly, then productivity is improved, but control over curing process becomes more difficult
Solution Approach 1:
The patent divides the curing process into separate stages by using multi-functional polythioethers that can undergo controlled crosslinking. The segmentation of curing stages allows rapid overall curing while maintaining process control through controlled addition of curing agents and management of reaction kinetics, resolving the contradiction between productivity and device complexity.
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 compositions provide a cured sealant with excellent fuel resistance, low temperature flexibility, and rapid curing, maintaining a tack-free film within an hour, with high elongation and tensile strength, and suitable for aerospace applications.
Implementation Method 1
comprise: (a) a first component comprising an isocyanate functional polythioether-polyurethane and/or polythiourethane; and (b) a second component comprising an amine/hydroxy-functional polythioether
Data Source
AI summary
Compositions, such as aerospace sealant, coating, and/or potting compositions are disclosed. The compositions include a polythioether and, in at least some cases, can be sprayable and fuel resistant even when substantially free of volatile organic compounds.