Prepreg Laminate Structure for Void-Free Composite Surfaces

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Solution Overview

Problem

Current fiber-reinforced composite materials often exhibit pinholes and voids due to air or volatile components in the resin, which hinder the achievement of a desired design surface and compromise the strength and peel strength of the material.

Innovation Solution

A prepreg laminate structure is developed, where prepregs with resin-impregnated fibers are stacked with a base material not impregnated with resin, with specific thickness and basis weight ranges, and subjected to heating and pressurizing under reduced pressure, allowing the resin to impregnate the base material and expel air and volatile components, thereby enhancing the design surface quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a base material not impregnated with resin is placed between prepreg layers, then undulation of fibers due to fluidity is suppressed and surface smoothing is achieved, but the design surface quality deteriorates due to pinholes and voids

Engineering Contradiction:
Improvesurface smoothingVSAvoiddesign surface quality
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

A resin-impregnated paper is introduced as an intermediary layer between the base material and the prepreg layers. This intermediary layer serves dual functions: it suppresses fiber undulation during molding while preventing pinhole formation on the design surface by providing a controlled resin barrier that blocks volatile components from reaching the surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a composite structure combining base material, resin-impregnated paper, and prepreg layers. This composite arrangement integrates the advantages of each component: the base material provides structural support, the resin-impregnated paper prevents surface defects, and the prepreg layers provide reinforcement, achieving both surface smoothing and high design surface quality.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If resin is impregnated into base material, then air and volatile components are expelled, but fiber volume fraction decreases

Engineering Contradiction:
Improvedesign surface qualityVSAvoidfiber volume fraction
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The resin-impregnated paper is applied locally only at the interface between the base material and prepreg layers, rather than impregnating the entire base material. This localized approach ensures that resin is present where needed to expel volatiles and prevent pinholes, while minimizing the overall resin content to maintain high fiber volume fraction in the final composite structure.

Inventive Principle:
Principle #3Local quality

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 results in a fiber-reinforced composite material with an excellent design surface and improved mechanical properties, reducing pinholes and voids while maintaining high fiber volume fractions, thus enhancing both design and structural integrity.

Implementation Method 1

the resin to impregnate the base material

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

subjected to heating and pressurizing under reduced pressure, allowing the resin to impregnate the base material and expel air and volatile components

Methodology Applied
Scientific EffectVacuum: Vacuum

Data Source

PatentEP3533575B1Prepreg laminate, fiber-reinforced composite material, and method for producing fiber-reinforced composite material
Publication Date: 2022.06.15 TORAY INDUSTRIES INC
  • EP3533575B1 patent drawingFigure 1~2
  • EP3533575B1 patent drawingFigure 3~4

AI summary

The present invention has an object to provide a fiber-reinforced composite material having an excellent design surface, a method for producing a fiber-reinforced composite material, and a prepreg laminate suitably used therein. The present invention is a prepreg laminate, including at least prepregs [a] having reinforcing fibers impregnated with a resin, and a base material [b] not impregnated with a resin, wherein at least two of the prepregs [a] are stacked in succession, and both sides of the base material [b] are sandwiched by the prepregs [a].