Segmented Prepreg Base Material for Fiber Flow Control

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Solution Overview

Problem

Existing fiber-reinforced plastic molding methods, such as SMC, struggle with irregular fiber distribution and orientation, leading to poor mechanical properties and defects like warp and surface sinks, especially in thin moldings, while prepreg base materials with incisions improve mechanical characteristics but lack sufficient strength for structural applications.

Innovation Solution

A prepreg base material with specific incision patterns, including slit segments aligned in certain directions and angles, and a laminated structure with alternating fiber orientations, allows for high flowability and flexible shaping while maintaining mechanical strength by controlling slit segment length and orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If continuous fibers are used in prepreg base material, then mechanical strength is improved, but flowability and flexible shaping ability deteriorate

Engineering Contradiction:
Improvemechanical strengthVSAvoidflowability and flexible shaping ability
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The continuous reinforcing fibers are divided into segments by making incisions at regular intervals through the thickness of the prepreg base material. This segmentation allows the fiber bundles to flow and adapt to complex mold shapes while maintaining sufficient mechanical strength through the controlled segment length and orientation.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If incisions are made in prepreg base material to improve flowability, then flexible shaping ability is improved, but mechanical strength deteriorates

Engineering Contradiction:
Improveflexible shaping abilityVSAvoidmechanical strength
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The incisions are made with specific local characteristics including controlled length, orientation angles (15-45 degrees relative to fiber direction), and spacing. This local quality control ensures that incisions provide sufficient flowability for shaping while minimizing damage to mechanical strength by avoiding excessive fiber disruption.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The prepreg base material consists of a composite structure combining continuous fibers with controlled incisions, creating a hierarchical composite that exhibits both flowability (from segmented structure) and mechanical strength (from continuous fiber segments and matrix resin).

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If chopped strands are used in SMC molding method, then flowability is improved, but fiber distribution uniformity and orientation regularity deteriorate

Engineering Contradiction:
ImproveflowabilityVSAvoidfiber distribution uniformity and orientation regularity
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The incisions are made in advance during prepreg manufacturing, establishing a predetermined fiber segmentation pattern before molding. This preliminary action ensures uniform fiber distribution and regular orientation throughout the molded product, eliminating the randomness associated with chopped strand SMC methods.

Inventive Principle:
Principle #10Preliminary action

4Stability of the object's composition

If continuous fibers are arranged regularly in prepreg, then mechanical property uniformity is improved, but ability to produce complicated three-dimensional shapes deteriorates

Engineering Contradiction:
Improvemechanical property uniformityVSAvoidability to produce complicated three-dimensional shapes
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

By segmenting the continuous fibers through controlled incisions, the prepreg base material can maintain regular fiber arrangement for mechanical uniformity while allowing the segmented bundles to flow and conform to complicated three-dimensional mold shapes during the molding process.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3501774B1Prepreg base material, laminated base material and fibre reinforced plastic
Publication Date: 2021.09.15 TORAY INDUSTRIES INC
  • EP3501774B1 patent drawingFigure 1
  • EP3501774B1 patent drawingFigure 2(a)~3A
  • EP3501774B1 patent drawingFigure 3B~4B

AI summary

A prepreg base material which comprises many reinforcing fibers arranged in one direction and a matrix resin present among the many reinforcing fibers. The prepreg base material has, throughout the whole surface, many incisions each extending in a direction crossing the reinforcing fibers, substantially all of the reinforcing fibers having been divided by one or more of the incisions. The reinforcing fiber segments formed by division by the incisions have a length (L) of 10-100 mm. The prepreg base material has a thickness (H) of 30-300 µm, and the content by volume (Vf) of the reinforcing fibers in the prepreg base material is 45-65%.