Aerospace Sealant Microcapsule Coating for Weight and Strength
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Solution Overview
Problem
Aerospace sealants with low density fillers face challenges in maintaining mechanical, chemical, and environmental performance requirements, particularly in reducing weight while ensuring adequate tensile strength, adhesion, and resistance to fuels and solvents, as increasing filler content can compromise these properties.
Innovation Solution
A composition comprising 50 wt % to 70 wt % of a thiol-terminated polythioether prepolymer, 15 wt % to 21 wt % of a polyepoxide, and 35 vol % to 55 vol % of low density microcapsules with a specific gravity less than 0.1, coated with an aminoplast resin, achieving a specific gravity less than 0.9, which enhances solvent resistance and maintains performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If increasing filler content to reduce weight, then specific gravity decreases, but mechanical properties such as tensile strength and adhesion deteriorate
Solution Approach 1:
The patent changes the physical and chemical parameters of the filler by coating microcapsules with polythiol-functionalized aminoplast resin, transforming them from simple fillers to functional composite particles that participate in the curing reaction and provide both weight reduction and mechanical reinforcement
Solution Approach 2:
The invention creates a composite filler system combining microcapsules with polythiol-functionalized aminoplast resin coating, where the composite structure provides both the weight reduction benefit of low-density fillers and the mechanical strength contribution of the resin-coated surface that integrates with the sealant matrix
2Weight of moving object
If increasing filler content to reduce weight, then specific gravity decreases, but adhesion to substrate deteriorates
Solution Approach 1:
The patent modifies the surface properties of the filler particles through polythiol-functionalized aminoplast resin coating, which changes the interface characteristics to improve bonding with the sealant matrix and substrate while maintaining the low density of the microcapsule core
Solution Approach 2:
The polythiol-functionalized aminoplast resin acts as an intermediary layer between the low-density microcapsule filler and the sealant matrix, facilitating strong interfacial adhesion and preventing delamination while allowing the filler to maintain its weight-reduction function
3Weight of moving object
If increasing filler content to reduce weight, then specific gravity decreases, but resistance to fuels and solvents deteriorates
Solution Approach 1:
The patent changes the surface chemistry of the filler particles by coating with polythiol-functionalized aminoplast resin, which provides chemical resistance to fuels and solvents, thereby protecting the filler-sealant interface from degradation while maintaining the weight reduction benefit
4Ease of manufacture
If using thermally expandable thermoplastic microcapsules without polythiol coating, then manufacturing simplicity is maintained, but solvent resistance deteriorates
Solution Approach 1:
The invention creates a composite filler system combining microcapsules with polythiol-functionalized aminoplast resin coating, where the composite structure provides both the weight reduction benefit of low-density fillers and the mechanical strength contribution of the resin-coated surface that integrates with the sealant matrix
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 solution provides aerospace sealants with improved solvent resistance, tensile strength, and adhesion while reducing weight, by optimizing the filler content and binder integrity, thus meeting demanding aerospace performance criteria.
Implementation Method 1
a sulfur-containing polymer such as a thiol-terminated polythioether prepolymer can be reacted with a polyepoxide curing agent in the presence of an amine catalyst to provide a cured product
Implementation Method 2
low density filler can be added to a coating composition... it is desirable that coatings and sealants have a specific gravity less than 1... the low density filler comprises low density microcapsules... achieving a specific gravity less than 0.9
Implementation Method 3
the low density filler comprises low density microcapsules with a specific gravity less than 0.1, coated with an aminoplast resin... Cured compositions comprising the thiol-functionalized coated microcapsules exhibited superior solvent resistance
Data Source
AI summary
Low density aerospace compositions and sealants are disclosed. The low density compositions and sealants are characterized by a high volume percent loading of low density microcapsules.