Structured Hybrid Adhesive Lightning Strike Protection
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Solution Overview
Problem
Existing adhesive technologies face challenges in maintaining structural integrity and pattern retention during the curing process, particularly with epoxy resins, where the rapid reaction of curatives can compromise the embossing relief patterns and limit the production of high-strength structural hybrid adhesive materials.
Innovation Solution
A method involving a two-step reactive system with a base epoxy resin and two epoxy curatives, where the first curative reacts rapidly to form an initial network while the second, latent curative remains unreacted, allowing for embossing and subsequent curing to create a high-strength structural hybrid adhesive with retained relief patterns, and optionally embedding a scrim or applying an electrically conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single epoxy curative is used to achieve rapid curing, then curing speed is improved, but the embossed relief patterns are compromised and structural integrity is reduced
Solution Approach 1:
The curing process is divided into two distinct stages using two different curatives: a first curative that reacts rapidly to provide initial set and pattern retention, and a second curative that reacts slowly to provide final structural strength. This segmentation allows each curative to perform its specific function without interfering with the other, resolving the contradiction between speed and precision.
Solution Approach 2:
The first curative performs preliminary action by rapidly reacting to establish the embossed relief patterns and provide initial structural framework before the second curative completes the curing process. This preliminary action ensures pattern retention is achieved before final curing, preventing pattern loss during the overall curing process.
2Strength
If a rapid-reacting curative is used to achieve high strength, then strength is improved, but the ability to emboss and retain patterns is worsened
Solution Approach 1:
The curative system is segmented into two components with different reactivity profiles. The first curative (rapid-reacting) provides initial strength and pattern establishment, while the second curative (slow-reacting) provides additional structural strength without compromising pattern retention. This segmentation allows the material to achieve high overall strength while maintaining manufacturing precision.
Solution Approach 2:
The invention changes the chemical parameters of the curative system by selecting curatives with vastly different reactivity characteristics (e.g., polymercaptan vs. polyamine). This parameter change enables control over the curing kinetics, allowing pattern retention during embossing while achieving high final strength through the combined action of both curatives.
3Strength
If epoxy resins are used to achieve high strength structural adhesive materials, then strength is improved, but processing flexibility and pattern retention are reduced
Solution Approach 1:
The curing process is made dynamic through the two-stage curative system. The first curative provides rapid initial reaction for quick handling and pattern setting, while the second curative continues the reaction slowly to achieve full strength. This dynamic progression allows processors to work with the material at different stages, improving processing flexibility while maintaining high final strength.
Solution Approach 2:
By changing the chemical composition parameters to include two different curatives with distinct reactivity profiles, the invention achieves both high strength and processing flexibility. The first curative enables rapid initial set for easy handling, while the second curative ensures complete curing for maximum strength, thus resolving the contradiction between ease of manufacture and structural performance.
4Stability of the object's composition
If the second curative reacts quickly with epoxy resin, then curing completeness is improved, but the embossed patterns are lost before curing is complete
Solution Approach 1:
The first curative performs preliminary action by rapidly reacting to establish and lock in the embossed relief patterns before the second curative begins its reaction. This preliminary pattern establishment prevents pattern loss, allowing the second curative to then react completely with the epoxy resin to achieve full curing completeness without compromising the already-established patterns.
Solution Approach 2:
The curing process is segmented into two sequential stages: first, rapid reaction with the first curative to establish patterns and provide initial structural framework; second, slow reaction with the second curative to achieve complete curing. This segmentation ensures that pattern retention occurs during the critical early stage, while curing completeness is achieved in the subsequent stage without pattern loss.
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
This approach enables the production of high-strength structural hybrid adhesive materials that maintain embossed patterns and allow for lightweight, patterned conductive layers, suitable for applications like lightning strike protection, with enhanced processing flexibility and material properties.
Implementation Method 1
reacting the base resin with the first epoxy curative such that the first epoxy curative is substantially reacted with epoxy resin in the article and the second epoxy curative is substantially unreacted in the article
Implementation Method 2
embossing the adhesive article with a relief pattern
Implementation Method 3
curing the adhesive article such that the second epoxy curative is substantially reacted with epoxy in the article
Implementation Method 4
depositing an electrically conductive layer such as a layer of metal onto the surface of the adhesive article embossed with a relief pattern
Data Source
AI summary
A method is provided for making structured hybrid adhesive articles such as lightning strike protection sheets. In the embodiment for making lightning strike protection sheets, the method comprises the steps of: a) providing an adhesive article comprising: i) a base resin comprising an epoxy resin, ii) a first epoxy curative, and iii) a second epoxy curative; b) reacting the base resin with the first epoxy curative such that the first epoxy curative is substantially reacted with epoxy resin in the article and the second epoxy curative is substantially unreacted in the article; c) embossing the adhesive article with a relief pattern; d) depositing an electrically-conductive layer onto at least a portion of the embossed surface; and e) curing the adhesive article such that the second epoxy curative is substantially reacted with epoxy in the article. In some embodiments, the method additionally comprises a step of embedding a scrim in the adhesive.