Carbon Fiber Bundle Processing for Stable Filament Winding
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Solution Overview
Problem
Existing carbon fiber bundles used in filament winding molding methods lack sufficient fracture toughness, stability, and uniformity, particularly when used in high-pressure applications like compressed hydrogen gas containers, leading to issues with tensile strength and composite quality.
Innovation Solution
A carbon fiber bundle production method involving controlled heat treatment, improved fracture toughness, and entanglement management, resulting in a bundle with 30,000 or more filaments, a tensile modulus of 265 to 300 GPa, and a stable yarn shape with minimal width variation, achieved through specific stabilization and carbonization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon fiber bundles with fewer than 30,000 filaments are used to achieve high tensile strength, then mechanical properties are improved, but productivity and composite manufacturing efficiency deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the stabilization temperature (200-300°C) and carbonization temperature (1000-2000°C) to produce carbon fiber bundles with 30,000 or more filaments that achieve both high tensile strength (5.0 GPa or more) and high productivity. This resolves the contradiction by changing the thermal processing parameters to enable high-filament-count bundles to attain previously unachievable strength levels.
2Productivity
If the number of filaments in carbon fiber bundle is increased to improve productivity, then composite manufacturing efficiency is improved, but tensile strength and uniformity deteriorate
Solution Approach 1:
The patent changes the thermal processing parameters by implementing controlled stabilization at 200-300°C followed by carbonization at 1000-2000°C, which enables carbon fiber bundles with 30,000 or more filaments to achieve tensile strength of 5.0 GPa or more. This resolves the contradiction by demonstrating that high filament count does not necessarily compromise strength when proper thermal parameters are applied.
Solution Approach 2:
The patent applies local quality by creating a controlled stabilization environment at 200-300°C before carbonization, which ensures uniform structural development across all filaments in the bundle. This localized thermal treatment approach ensures that even with 30,000 or more filaments, each filament develops consistent properties, maintaining uniformity and tensile strength.
3Ease of manufacture
If conventional stabilization processes are used to improve manufacturing simplicity, then process complexity is reduced, but fracture toughness and tensile strength deteriorate
Solution Approach 1:
The patent changes the stabilization temperature parameter to a specific range of 200-300°C, which is optimized to improve fracture toughness while maintaining process simplicity. This controlled temperature range enables the formation of a stable precursor structure that enhances fracture toughness without requiring complex multi-stage processes.
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
The method produces a carbon fiber bundle with enhanced tensile strength, stability, and uniformity, enabling high-quality carbon fiber-reinforced composites with reduced weight and consistent properties, suitable for high-pressure applications.
Implementation Method 1
a first stabilization process of stabilizing the polyacrylonitrile precursor fiber bundle for carbon fiber obtained in the gathering process
Implementation Method 2
a carbonization process of carbonizing the stabilized fiber bundle obtained in the second stabilization process
Data Source
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AI summary
The purpose of the present invention is to provide: a carbon fiber bundle which exhibits excellent filament shape stability when forming a composite material, and from which it is possible to obtain a carbon fiber composite material which exhibits high tensile strength; and a method for producing the same. To achieve this purpose, the provided carbon fiber bundle exhibits a tensile elasticity as a resin-impregnated strand of 265-300 GPa, a tensile strength as a resin-impregnated strand of 6.0 GPa or more, a knot strength of 820 N/mm2 or more, a filament number of 30,000 or more, and an average tear distance of 600-850 mm, wherein the rate of change in filament width is 8% or less when the carbon fiber bundle is unraveled under the conditions stipulated in the description, and there are four or fewer sections per 1,000 m which exhibit a filament width equal to or less than 75% of the average filament width when the carbon fiber bundle is unraveled under the conditions stipulated in the description.