Carbon Fiber Assembly Granulation for High Bulk Density

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Solution Overview

Problem

Existing methods for producing fiber assemblies fail to achieve high bulk density while maintaining fiber length, leading to inefficiencies in supplying fibers and compromising the physical properties of fiber-reinforced resin compositions.

Innovation Solution

A method involving stirring and granulating fibers with a fiber treatment agent using a stirring tank, rolling tank, or applying strain rate to align fibers without cutting, utilizing equipment like Henschel mixers or granulators to promote fiber alignment and crosslinking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional granulation methods (wet extrusion, stirring with flexible spheres) are used to produce fiber assemblies, then fibers can be bundled and handled, but the bulk density remains low and fiber length is reduced due to cutting

Engineering Contradiction:
Improvebulk densityVSAvoidfiber length
Core Design Contradiction:
Quantity of substanceVSLength of moving object

Solution Approach 1:

The patent replaces conventional mechanical granulation systems (wet extrusion, stirring tanks with flexible spheres) with a high-speed rotary granulator that uses centrifugal force and impact mechanisms. This mechanical system substitution enables dense packing of fibers into spherical granules with bulk density of 0.3 g/cm³ or more while maintaining fiber length through non-cutting granulation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the granulation parameters by controlling the rotation speed of the granulator (500-2000 rpm), the feed rate of fibers, and the moisture content of the binding agent. These parameter changes enable achieving high bulk density (0.3 g/cm³ or more) while preventing fiber cutting through optimized granulation conditions

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If fibers are granulated using conventional methods to improve handling, then workability increases, but supply stability from feeders deteriorates due to low bulk density causing fiber bridging

Engineering Contradiction:
ImproveworkabilityVSAvoidsupply stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces conventional granulation equipment with a high-speed rotary granulator that produces uniformly dense spherical granules. This mechanical system substitution ensures consistent bulk density (0.3 g/cm³ or more) that prevents fiber bridging in feeders while maintaining excellent workability in resin mixing processes

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If wet extrusion granulation is used to produce fiber assemblies with epoxy resin-based sizing agents, then fibers can be supplied stably, but the production efficiency is low and equipment complexity increases

Engineering Contradiction:
Improvesupply stabilityVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the complex wet extrusion granulation system with a simpler high-speed rotary granulator that uses centrifugal force and impact for granulation. This mechanical substitution maintains supply stability through consistent granule density while dramatically improving production efficiency through faster processing speeds

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the granulation approach by using high-speed rotation (500-2000 rpm) and controlling granule formation through centrifugal force rather than wet extrusion. This parameter change enables rapid production of high-density granules with stable supply characteristics

Inventive Principle:
Principle #35Parameter changes

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

Results in a fiber assembly with high bulk density, enabling efficient supply and stable dispersion of fibers, enhancing the physical properties of resin compositions and prepreg sheets.

Implementation Method 1

stirring and granulating fibers with a fiber treatment agent using a stirring tank, rolling tank, or applying strain rate to align fibers without cutting, utilizing equipment like Henschel mixers or granulators

Methodology Applied
Scientific EffectMechanical stirring and granulation: Stirring

Data Source

PatentEP4357496B1Method for producing fiber assembly and method for producing prepreg sheet
Publication Date: 2026.02.11 MITSUBISHI CHEM CORP
  • EP4357496B1 patent drawingFigure 1a~1b
  • EP4357496B1 patent drawingFigure 2a~3A
  • EP4357496B1 patent drawingFigure 3B

AI summary

A method for producing a fiber assembly, including: putting a plurality of fibers and a fiber treatment agent into a stirring tank; and stirring a mixture of the fibers and the fiber treatment agent with a stirring blade to granulate the mixture, wherein the fibers include carbon fibers, and the mixture is granulated such that the fibers are aligned. A method for producing a fiber assembly, wherein a plurality of fibers containg carbon fibers and a liquid are put into a stirring tank and the mixture of the fibers and the liquid is stirred with a stirring blade, thereby obtaining a fiber assembly which has a spheroidal shape or a strand shape.