Sandwich Panel Molding with High-Tg Foam Cores
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Solution Overview
Problem
The use of resin foam core materials in sandwich panels results in significant thickness changes during the curing process due to swelling and adhesive impregnation, leading to excessive crushing and non-uniform thickness, which is particularly problematic for applications requiring precise dimensions and heat resistance.
Innovation Solution
The method involves using a super engineering plastic foam with a glass transition temperature above 200°C as the core material and a skin material composed of an epoxy resin with specific molecular weights and structures, along with a curing agent, to minimize thickness changes during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a resin foam core material with high foaming ratio and low bulk density is used, then the lightweight property is improved, but the thickness change during curing exceeds 50% due to swelling and adhesive impregnation
Solution Approach 1:
The patent changes the material parameter of the core material from conventional resin foam to super engineering plastic foam with glass transition temperature above 200°C. This parameter change fundamentally alters the thermal and mechanical properties of the core material, enabling it to resist swelling and deformation at curing temperatures while maintaining lightweight characteristics.
Solution Approach 2:
The patent creates a composite structure by combining super engineering plastic foam core material with skin materials (prepreg or adhesive). This composite approach allows the core material to provide structural stability and resistance to thickness change while the skin materials provide surface integrity and bonding, achieving both lightweight property and manufacturing precision.
2Weight of moving object
If a core material with high void ratio is used to achieve low bulk density, then the lightweight property is improved, but the rigidity decreases due to swelling and adhesive impregnation
Solution Approach 1:
The patent changes the glass transition temperature parameter of the core material to above 200°C, which fundamentally alters the material's thermal stability and rigidity characteristics. This enables the material to maintain its structural integrity and rigidity during the curing process despite having high void ratio and low bulk density.
3Temperature
If heat resistance exceeding 150°C is required, then the heat resistance is improved, but the material selection is restricted for both skin material and core material
Solution Approach 1:
The patent raises the glass transition temperature parameter of the core material to above 200°C, which inherently provides heat resistance exceeding 150°C. This parameter change expands material selection versatility because the super engineering plastic foam core can be paired with various skin materials including epoxy resins, polyester resins, vinyl ester resins, and natural fiber prepregs, rather than being limited to high-temperature materials like phenolic resins or polyimides.
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 reduces thickness variation to less than 10%, ensuring uniformity and suitability for applications requiring radio wave characteristics and precise dimensions.
Implementation Method 1
The (a) core material is a super engineering plastic foam having a glass transition temperature of greater than 200°C
Implementation Method 2
The (b) skin material contains: a (b-1) epoxy resin having an average molecular weight of 1300 or more or having a trishydroxymethane-type or cresol novolac-type structure; and a (b-3) curing agent
Data Source
Figure 1
AI summary
A method of molding a sandwich panel according to an embodiment of the present invention includes a step of providing, on one or both surfaces of an (a) core material, a prepreg or the prepreg and an adhesive as a (b) skin material. The (a) core material is a super engineering plastic foam having a Tg of greater than 200°C. The (b) skin material contains: a (b-1) epoxy resin having an average molecular weight of 1300 or more or having a trishydroxymethane-type or cresol novolac-type structure and containing, in a total epoxy resin, an amount of 70 to 100 mass% of an epoxy resin that is semi-solid or solid; a (b-2) epoxy resin containing, in the total epoxy resin, an amount of 0 to 30 mass% of an epoxy resin that is liquid; and a (b-3) curing agent.