Partially Reacted Silane Primer for Aerospace Sealant Adhesion
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Solution Overview
Problem
Current aerospace sealants face challenges in achieving strong adhesion to a wide range of surfaces, including aerospace-grade metals and composites, especially under exposure to solvents like aviation fuel and varying environmental conditions, and existing adhesion promoters are not universally effective.
Innovation Solution
The use of partially reacted silane primer compositions, specifically formulated with amino-functional alkoxysilanes, organo-functional alkoxysilanes reactive with thiol groups, and water, which are applied as coatings to enhance the adhesion of aerospace sealants by forming a thin, homogeneous film that reacts directly with surfaces to improve bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesion promoters are added to sealant compositions or applied as pretreatments, then dry adhesion to certain surfaces is improved, but adhesion following solvent immersion (particularly aviation fuel) deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the adhesion promoter by using partially reacted silanes with specific functional groups (epoxy, amino, or isocyanate) that can crosslink with both the substrate and the sealant. This chemical parameter change enables the promoter to maintain adhesion strength both in dry conditions and after solvent immersion, resolving the contradiction between initial adhesion and solvent resistance.
Solution Approach 2:
The invention creates a composite adhesion promoter system that combines multiple functional components: silane base molecules, crosslinking agents (epoxy, amino, or isocyanate groups), and coupling agents. This composite structure allows the promoter to simultaneously provide dry adhesion and solvent resistance by forming a multi-functional interfacial layer between substrate and sealant.
2Strength
If adhesion promoters are used to improve surface adhesion, then bonding to certain surfaces is enhanced, but universality across all surface types deteriorates
Solution Approach 1:
The invention achieves universality by designing adhesion promoters with multiple reactive functional groups that can interact with diverse surface chemistries. The silane-based promoters with epoxy, amino, or isocyanate groups can bond to metals, composites, and coated surfaces alike, while the crosslinking capability provides consistent performance across different substrate types, resolving the contradiction between targeted adhesion enhancement and broad applicability.
3Strength
If fully reacted silane compositions are used as primers, then adhesion promotion is achieved, but application flexibility and reactivity control deteriorate
Solution Approach 1:
The invention applies preliminary action by partially reacting silanes before application to create pre-formed adhesion promoters with controlled reactivity. These partially reacted silanes are prepared in advance with specific functional groups that will react with the sealant, but remain stable during storage and application. This allows flexible application timing and conditions while ensuring reliable adhesion promotion when the sealant is applied, resolving the contradiction between adhesion strength and operational flexibility.
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 partially reacted silane primer compositions significantly enhance the adhesion strength of aerospace sealants to various surfaces, including those exposed to solvents and extreme conditions, by forming a robust bond through direct surface reaction, thereby meeting the demanding performance requirements of the aerospace industry.
Implementation Method 1
the reaction products of reactants comprising (i) an amino-functional alkoxysilane; (ii) an organo-functional alkoxysilane
Implementation Method 2
the reaction products of reactants comprising (i) an amino-functional alkoxysilane; (ii) an organo-functional alkoxysilane; and (iii) water
Implementation Method 3
applying the composition to the surface; drying the composition to provide a dried primer coating
Implementation Method 4
wherein the organo group is reactive with a thiol group
Data Source
Figure 1
Figure 2~3
Figure 4A
AI summary
Partially reacted alkoxysilane compositions, the use of partially reacted alkoxysilane compositions as adhesion-promoting primer coatings, and methods of using the partially reacted alkoxysilane compositions and coatings are disclosed.