Carbon Fiber Bundle Mass Variation Reduction via Segmented Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for improving carbon fiber quality, such as controlling skin-core structure and stabilization temperature, do not effectively address the variation in mass per unit length, which affects the mechanical properties and consistency of carbon fiber bundles.
Innovation Solution
The method involves increasing the fineness of precursor fibers, controlling the stretch ratio in the spinning and stabilization steps, and using a two-stage stabilization process to achieve a carbon fiber bundle with reduced variation in mass per unit length, while maintaining high tensile strength and modulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional stabilization methods are used to improve carbon fiber quality, then mechanical properties such as tensile strength and tensile modulus can be improved, but the variation in mass per unit length increases
Solution Approach 1:
The stabilization process is divided into two distinct stages: first stabilization and second stabilization. This segmentation allows independent optimization of each stage - the first stage focuses on forming stable structure while the second stage focuses on reducing mass variation, thereby resolving the contradiction between improving strength and reducing mass variation.
Solution Approach 2:
The invention changes multiple parameters systematically: stabilization temperatures (200-300°C for first stage, 300-400°C for second stage), stabilization times (5-60 minutes for first stage, 5-30 minutes for second stage), and stretch ratios (1.05-1.20 for first stage, 1.20-1.35 for second stage). These parameter changes enable simultaneous improvement of tensile strength and reduction of mass per unit length variation.
2Strength
If stretching is performed to improve tensile modulus and reduce skin-core structure difference, then mechanical properties improve, but mass per unit length variation increases
Solution Approach 1:
Stretching operations are segmented into two stages corresponding to the two stabilization stages. The first stretching (ratio 1.05-1.20) occurs during first stabilization, and the second stretching (ratio 1.20-1.35) occurs during second stabilization. This segmented approach allows progressive orientation improvement while controlling mass variation through the second stabilization process.
Solution Approach 2:
The first stabilization and first stretching are performed as preliminary actions to establish basic fiber structure and orientation. Then the second stabilization and second stretching are performed as follow-up actions to fine-tune the structure and reduce mass variation, achieving both high tensile modulus and low mass variation.
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 carbon fiber bundle with a low coefficient of variation in mass per unit length, leading to improved fiber content stability and the production of high-performance composite materials with consistent mechanical properties.
Implementation Method 1
stabilization treatment... in an oxidation oven... stabilization temperature with respect to the specific gravity are carried out
Implementation Method 2
subjecting the stabilized fiber bundle to a heat treatment in an inert atmosphere at a temperature of from 1,200 to 3,000°C, to obtain the carbon fiber bundle
Data Source
AI summary
An object of the present invention is to provide a carbon fiber bundle having a small variation in the mass per unit length (g/m) of the carbon fiber bundle, and having an excellent tensile strength of resin-impregnated strands and tensile modulus of resin-impregnated strands. To achieve the above-mentioned object, the present invention provides a carbon fiber bundle having a tensile strength of resin-impregnated strands of from 4.5 to 6.5 GPa, a tensile modulus of resin-impregnated strands of from 205 to 270 GPa, the number of filaments of from 6,000 to 36,000, and a coefficient of variation represented by the ratio of the standard deviation to the mean value of the mass per unit length (g/m) of the carbon fiber bundle, of from 0.00 to 0.5%.