B-staging Pre-preg Using Capacitively-Coupled RF Heating

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Solution Overview

Problem

Current methods for manufacturing industrial-grade fiber composites using pre-pregs, which involve B-staging in ovens, often result in inferior products due to inconsistent crosslinking, leading to excessive resin flow or delamination issues during lamination.

Innovation Solution

The use of electromagnetic heating with fringing field capacitors and radio frequency (RF) alternating current (AC) to control cross-linking in pre-preg materials, allowing for precise temperature control and faster, more efficient curing of carbon fiber and carbon nanotube composites.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional oven heating is used for B-staging pre-preg, then temperature control is achieved, but crosslinking consistency deteriorates leading to resin flow or delamination issues

Engineering Contradiction:

Improvetemperature controlVSAvoidcrosslinking consistency

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent replaces conventional thermal conduction heating from ovens with electromagnetic induction heating. The induction heating system uses a magnetic field generated by a coil to induce eddy currents within the pre-preg material, creating internal heat generation rather than external heat transfer. This substitution of heating mechanism enables more uniform and consistent crosslinking throughout the pre-preg, eliminating the resin flow and delamination issues associated with conventional oven heating while maintaining temperature control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If conventional oven heating is used for B-staging pre-preg, then crosslinking is achieved, but processing time increases and productivity decreases

Engineering Contradiction:

Improvecrosslinking degreeVSAvoidprocessing speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The induction heating system employs periodic alternating current at high frequency (typically 20-100 kHz) to generate oscillating magnetic fields that continuously induce eddy currents in the conductive filler particles within the pre-preg. This periodic action enables rapid and uniform heating throughout the material, significantly reducing the processing time required to achieve the desired crosslinking degree compared to conventional oven heating, thereby improving productivity while maintaining manufacturing precision.

Inventive Principle:

Principle #19Periodic action

3Temperature

If conventional oven heating is used for B-staging pre-preg, then heating is achieved, but energy consumption increases and cost increases

Engineering Contradiction:

Improveheating capabilityVSAvoidenergy consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The induction heating process utilizes the inherent electrical conductivity of filler particles (such as carbon black, metal oxides, or conductive polymers) already present in the pre-preg formulation. These filler particles act as internal heating elements that generate heat through eddy currents when exposed to the alternating magnetic field. This self-heating mechanism eliminates the need for extensive external heating infrastructure and reduces energy consumption compared to conventional oven heating, as the heat is generated directly within the material itself rather than being transferred from an external source.

Inventive Principle:

Principle #25Self-service

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 method achieves rapid and uniform heating rates, reducing energy costs and fabrication time, while enabling tailored crosslinking levels, thus improving the quality and consistency of fiber composites.

Implementation Method 1

applying electromagnetic heating to a composition including a fiber and a resin, where the electromagnetic heating is conducted with at least one fringing field capacitor utilizing radio frequency (RF) alternating current (AC) and controlling cross-linking of the resin in the composition via the electromagnetic heating

Methodology Applied

Scientific EffectElectromagnetic heating: Dielectric Heating

Implementation Method 2

electromagnetic heating is conducted with at least one fringing field capacitor utilizing radio frequency (RF) alternating current (AC)

Methodology Applied

Scientific EffectRadio frequency heating: Dielectric Heating

Data Source

PatentUS20240375317A1B-staging of pre-preg using capacitively-coupled electromagnetic heating method

Publication Date: 2024.11.14 TEXAS A&M UNIVERSITY

AI summary

A method of fabrication processing a pre-preg material includes applying electromagnetic heating to a composition including a fiber and a resin. The electromagnetic heating is conducted with at least one fringing field capacitor utilizing radio frequency (RF) alternating current (AC) and controlling cross-linking of the resin in the composition via the electromagnetic heating.