Conductive-Core Prepreg Composition for Impact-Resistant CFRP

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Solution Overview

Problem

Carbon fiber reinforced composite materials face challenges in achieving both high impact resistance and conductivity, as existing methods often compromise one property for the other, resulting in either low conductivity or low impact resistance.

Innovation Solution

A prepreg composition is developed that includes carbon fibers and a thermosetting resin, with conductive particles or fibers having a thermoplastic resin nucleus or core coated with a conductive substance, which enhances impact resistance and conductivity without decreasing carbon fiber content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a resin layer with dispersed thermoplastic resin particles is provided on the surface region of the prepreg to improve impact resistance, then the impact resistance is improved, but the conductivity in thickness direction significantly decreases due to the formation of an insulating layer

Engineering Contradiction:
Improveimpact resistanceVSAvoidconductivity in thickness direction
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies local quality by providing a resin layer with dispersed particles only in the surface region (interlayer) of the prepreg, while maintaining the base material's properties in the bulk. This localized modification allows the interlayer to have enhanced toughness and impact resistance, while the carbon fiber layers maintain their inherent conductivity. The resin layer thickness is controlled to be 1-10 μm, creating a thin functional layer that improves impact resistance without significantly compromising conductivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining thermoplastic resin particles (nylon, polyethylene terephthalate, etc.) with the thermosetting resin matrix in the interlayer region. This creates a multi-phase composite structure where the thermoplastic particles provide toughness and impact resistance, while the thermosetting resin provides structural integrity. The combination allows simultaneous achievement of high impact resistance and maintained conductivity through proper particle selection and distribution.

Inventive Principle:
Principle #40Composite materials

2Reliability

If carbon fiber content is increased to improve conductivity, then the conductivity is improved, but the impact resistance does not improve drastically since it is determined by delamination strength

Engineering Contradiction:
ImproveconductivityVSAvoidimpact resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent segments the prepreg structure into distinct functional regions: carbon fiber layers for conductivity and strength, and a separate resin layer with dispersed particles in the interlayer region for impact resistance. This segmentation allows each layer to be optimized independently - carbon fiber content can be increased for conductivity without compromising impact resistance, as the impact resistance is provided by the particle-dispersed resin layer that prevents delamination.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses spherical or particulate form of thermoplastic resin particles dispersed in the interlayer. These particles act as stress distributors and toughness enhancers, preventing crack propagation and improving delamination resistance. The particulate morphology allows efficient space utilization and uniform distribution in the resin matrix, providing impact resistance without significantly affecting conductivity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Strength

If a polysulfone oligomer is added to improve matrix resin toughness, then the toughness is improved, but it still results in producing a resin layer that becomes an insulating layer, decreasing conductivity

Engineering Contradiction:
ImprovetoughnessVSAvoidconductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent uses thermoplastic resin particles as intermediary elements in the interlayer region. These particles act as mediators that improve the toughness of the resin matrix without forming a continuous insulating layer. The particles are dispersed individually rather than forming a continuous phase, allowing electrical conductivity to be maintained through the carbon fiber network while the particle-reinforced resin provides enhanced toughness and impact resistance.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution enables carbon fiber reinforced composite materials to simultaneously exhibit excellent impact resistance and conductivity, balancing both properties effectively.

Implementation Method 1

conductive particle or fiber of which thermoplastic resin nucleus or core is coated with conductive substance

Methodology Applied
Scientific EffectConduction (electrical): Conduction (electrical)

Data Source

PatentEP2452967B1Prepreg and carbon fibre-reinforced composite material
Publication Date: 2013.10.02 TORAY INDUSTRIES INC
  • EP2452967B1 patent drawingFigure 1

AI summary

A prepreg containing a carbon fiber [A] and a thermosetting resin [B], and in addition, satisfying at least one of the following (1) and (2) . (1) a thermoplastic resin particle or fiber [C] and a conductive particle or fiber [D] are contained, and weight ratio expressed by [compounding amount of [C] (parts by weight)]/[compounding amount of [D] (parts by weight)] is 1 to 1000. (2) a conductive particle or fiber of which thermoplastic resin nucleus or core is coated with a conductive substance [E] is contained.