Solid Epoxy Expansion Material for Tack-Free Structural Reinforcement
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Solution Overview
Problem
Existing thermally expansible materials face challenges in maintaining mechanical properties across a wide temperature range, being processable without premature curing or degradation, and avoiding tackiness during handling, while also providing effective structural reinforcement.
Innovation Solution
A solid thermally expansible material comprising a solid epoxy resin, impact modifier, and heat-activated foaming agent, with minimal liquid or semi-solid epoxy resin, and optionally aramid fibers for moisture control, ensuring tack-free handling and high glass transition temperatures, along with stable expansion and adhesion to substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquid epoxy resin and semi-solid epoxy resin are used in the thermally expansible material, then the material is easier to process and handle, but the material becomes tacky on the outer surface and may undergo premature curing or degradation in high humidity and temperature environments
Solution Approach 1:
The patent changes the physical state parameter of the epoxy resin from liquid/semi-solid to solid form. This parameter change eliminates the tackiness issue and improves stability against premature curing while maintaining processability through the solid state processing route
Solution Approach 2:
The patent utilizes the phase transition of epoxy resin from liquid/semi-solid to solid state. By employing solid epoxy resin, the material avoids the harmful effects of liquid epoxy (tackiness, premature curing) while retaining the necessary workability during the expansion process
2Temperature
If the glass transition temperature of the cured material is increased to maintain mechanical properties at high temperatures, then the material maintains integrity better, but the material becomes more brittle and harder to process
Solution Approach 1:
The patent optimizes the glass transition temperature parameter to a specific range (90-110°C) that balances high-temperature performance with processability. This parameter optimization ensures the material remains workable during processing while maintaining structural integrity at service temperatures
3Strength
If the material is made more rigid to provide better structural reinforcement, then the reinforcement effectiveness increases, but the material becomes more brittle and less adaptable to substrate contours
Solution Approach 1:
The patent employs a two-stage behavior: during the expansion phase, the material remains flexible and adaptable to substrate contours; after curing, it transitions to a rigid state providing structural reinforcement. This dynamic transition resolves the contradiction between rigidity and adaptability
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 material maintains mechanical integrity across -40°C to 80°C, is easily processable, and provides effective structural reinforcement with minimal tackiness and controlled expansion, enhancing durability and adhesion.
Implementation Method 1
heat-activated foaming agent
Implementation Method 2
The material is then heated to an activation temperature. When the material is activated, it expands. Upon expansion, the material adheres to at least a portion of the substrate. Following expansion, the material is cured.
Data Source
Figure 1~3
Figure 4~5
AI summary
A solid thermally expansible material is provided. The material includes a solid epoxy resin that is substantially free of liquid epoxy resin and semi-solid epoxy resin. The material also includes an impact modifier, a curing agent and a heat-activated foaming agent. The impact modifier includes rubber in one embodiment and is substantially free of rubber in another embodiment. Following heat activation, the material expands and can adhere to a substrate. A cured expanded reinforcement material is also provided, as is a method of reinforcing a substrate.