Prepreg Surface Layer Conductive Bridge for CFRP Impact Resistance
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Solution Overview
Problem
Current prepregs used for carbon fiber reinforced composite materials (CFRP) face challenges in achieving both high impact resistance and conductivity, particularly in the thickness direction, due to the limitations of thermosetting and thermoplastic resin compositions, which often result in low mechanical properties and insufficient conductivity for applications requiring electromagnetic shielding and lightning protection.
Innovation Solution
A prepreg is developed with a primary layer impregnated by a resin composition containing an epoxy resin and thermoplastic resin, and a surface layer composed of an epoxy resin composition with conductive particles, where the conductive particles remain in the surface layer to act as a conductive bridge between reinforcing fiber layers, enhancing conductivity and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermosetting resin is used as the resin constituting the prepreg, then the tackiness and draping property are improved, but the impact resistance is lowered
Solution Approach 1:
The patent uses a composite resin system combining thermosetting resin (for tackiness and draping) with thermoplastic resin (for impact resistance). The thermoplastic resin forms a continuous phase that bridges fiber layers, providing toughness while the thermosetting resin provides processing characteristics. This composite approach allows simultaneous achievement of both ease of operation and strength.
Solution Approach 2:
The patent applies thermoplastic resin specifically at the fiber-layer interfaces and in the bulk matrix where impact resistance is needed, while maintaining thermosetting resin properties in the overall matrix structure. This localized application of thermoplastic resin provides targeted reinforcement without compromising the overall tackiness and draping properties.
2Strength
If thermoplastic resin fine particles are localized on the surface of the prepreg to improve impact resistance, then the impact resistance is improved, but the conductivity in the thickness direction is lowered
Solution Approach 1:
The patent changes the physical state and distribution parameters of the thermoplastic resin by using it as a continuous phase rather than discrete surface particles. This continuous distribution maintains electrical conductivity pathways between fiber layers while providing impact resistance through the same continuous matrix structure.
Solution Approach 2:
The thermoplastic resin acts as an intermediary material that simultaneously serves multiple functions: it provides impact resistance through toughness, maintains conductivity by forming continuous pathways between conductive fiber layers, and enables proper resin distribution during processing. This mediator role resolves the contradiction between impact resistance and conductivity.
3Reliability
If conductive particles are added to the resin composition to improve conductivity, then the conductivity is improved, but the manufacturing complexity is increased
Solution Approach 1:
The patent merges the conductivity function with the existing thermoplastic resin matrix rather than adding separate conductive additives. The thermoplastic resin itself forms the conductive pathways through its continuous distribution at fiber interfaces, eliminating the need for additional conductive particles and simplifying the manufacturing process.
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 prepreg achieves high impact resistance and conductivity in the thickness direction, suitable for applications such as aerospace and electromagnetic shielding, while maintaining excellent storage stability and handling properties.
Implementation Method 1
the conductive particles remain in the surface layer to act as a conductive bridge between reinforcing fiber layers, enhancing conductivity
Implementation Method 2
a primary prepreg composed of a reinforcing fiber, and a resin composition (I) with which a reinforcing fiber layer formed from the reinforcing fiber has been impregnated
Data Source
AI summary
The invention provides a prepreg comprising: a primary prepreg composed of reinforcing fibers and a resin composition (I) impregnating the interior of a reinforcing fiber layer formed from these fibers; and a surface layer composed of a resin composition (II) formed on one or both sides of the primary prepreg; wherein the resin composition (I) is an epoxy resin composition [B] containing at least an epoxy resin and a thermoplastic resin, and the resin composition (II) is an epoxy resin composition [A] containing at least an epoxy resin and conductive particles.