Carbon fiber bundle
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Solution Overview
Problem
Existing carbon fiber bundles, particularly large-tow bundles, suffer from insufficient process stability during further processing due to insufficient control of fibrils and voids, leading to fuzz generation, despite improvements in strand strength and production process fuzz suppression.
Innovation Solution
A carbon fiber bundle with controlled fibril and void ratios, where fibrils with an aspect ratio of 3.0 to 10.0 and voids of not less than 100 nm are managed within specific ranges, combined with a silicone oil agent of appropriate kinematic viscosity, to enhance process stability and reduce fuzz generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large-tow carbon fiber bundles are used to reduce cost and increase productivity, then processing unit and processing density increase, but strand strength, fuzz number, and processability deteriorate
Solution Approach 1:
The invention applies parameter changes by precisely controlling the kinematic viscosity of the silicone oil agent within 6000 to 20000 mm²/sec and the silicon content within 0.06 to 0.09 mass%, which transforms the processability and reliability parameters of large-tow carbon fiber bundles while maintaining high productivity
2Ease of manufacture
If silicone oil agent with insufficient kinematic viscosity is used to suppress fuzz generation, then application is simpler, but void suppression and fuzz generation prevention during further processing become insufficient
Solution Approach 1:
The invention changes the kinematic viscosity parameter of the silicone oil agent to a specific range (6000-20000 mm²/sec), which is higher than conventional values, to achieve both ease of manufacture and improved reliability by suppressing voids and preventing fuzz generation during further processing
3Productivity
If high number of filaments is used to increase total fineness and productivity, then cost reduction is achieved, but strand strength and processability deteriorate
Solution Approach 1:
The invention applies parameter changes by controlling the silicon content within 0.06 to 0.09 mass% and using silicone oil with specific kinematic viscosity, which maintains strand strength even when the number of filaments is increased to 40,000 or more for high productivity
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 solution results in a carbon fiber bundle with excellent strength and process stability, suitable for high fineness and productivity, enabling favorable spreadability and adhesion prevention, thereby improving the quality of carbon fiber-reinforced composite materials.
Implementation Method 1
the kinematic viscosity of the oil agent is 6000 to 20000 mm2/sec, and the silicon content is 0.06 to 0.09 mass%
Data Source
AI summary
A carbon fiber bundle including fibers having a surface on which a fibril(s) is/are present along the fiber axis direction, wherein in a single fiber tensile test at a gauge length of 50 mm in accordance with JIS R7606 (2000), the ratio of the number of fibers having a fracture surface where a fibrillar substance(s) with an aspect ratio of 3.0 to 10.0 is/are present in the fracture origin is 1 to 20%, and the ratio of the number of fibers having a fracture surface where a void(s) of not less than 100 nm is/are present in the fracture origin is 1 to 14%, and wherein the number of filaments is 48,000 to 60,000. An object of the present invention is to provide a carbon fiber bundle having excellent strength, and excellent process stability during further processing, while having high total fineness.