Carbon Fiber Bundle Production via Precursor Modification
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Solution Overview
Problem
Existing methods for producing carbon fiber bundles face challenges such as insufficient ladder structure formation during flameproofing, leading to strength reduction, and variability in modulus of elasticity due to short flameproofing times, especially when dealing with large numbers of fibers, which complicates the production of high-strength and uniform carbon fiber bundles.
Innovation Solution
The production method involves thickening the single fiber fineness of polyacrylonitrile-based precursor fiber bundles to achieve a carbon fiber bundle with a single fiber fineness of at least 0.8 dtex to 2.1 dtex, utilizing a heat treatment process under an oxidizing atmosphere and carbonization at high temperatures to ensure a strand strength of at least 4.9 GPa and a strand modulus of elasticity of at least 200 GPa, while maintaining a low variability in single fiber modulus of elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the acrylonitrile ratio is reduced to 92.5% in the precursor polymer, then the cost of raw materials is reduced, but the ladder structure formation during flameproofing becomes insufficient, leading to decomposition and gasification during carbonization and defect hole formation that reduces carbon fiber bundle strength
Solution Approach 1:
The invention changes the chemical composition parameters of the precursor polymer by introducing carboxylic acid groups through copolymerization with acrylic acid or methacrylic acid. This chemical modification enables sufficient ladder structure formation during flameproofing even with reduced acrylonitrile content (90-96 mol%), thereby maintaining carbon fiber bundle strength while reducing raw material costs.
2Manufacturing precision
If the flameproofing treatment time is extended to ensure uniform treatment of all fibers in the bundle, then the uniformity of modulus of elasticity improves, but the production efficiency and productivity decrease
Solution Approach 1:
The invention changes the chemical structure of the precursor polymer by introducing carboxylic acid groups that catalyze ladder structure formation. This chemical modification accelerates the flameproofing reaction kinetics, allowing uniform treatment of all fibers in the bundle within a shorter time frame (1-24 hours at 200-300°C), thereby achieving both uniform modulus of elasticity and high production efficiency.
3Strength
If the number of single fibers in the carbon fiber bundle is increased to exceed 6000 fibers, then the strand strength increases, but the variability in modulus of elasticity between fibers increases due to uneven flameproofing treatment
Solution Approach 1:
The invention changes the chemical composition of the precursor polymer by incorporating carboxylic acid groups from acrylic acid or methacrylic acid copolymerization. This chemical modification ensures uniform flameproofing treatment across all fibers in large bundles (6000-50000 fibers) by promoting consistent ladder structure formation, thereby achieving both high strand strength and uniform modulus of elasticity throughout the bundle.
4Productivity
If the single fiber fineness is thickened to at least 0.8 dtex to 2.1 dtex, then the production output and cost efficiency improve, but the mechanical properties must be maintained at high levels
Solution Approach 1:
The invention changes the chemical structure of the precursor polymer by introducing carboxylic acid groups that facilitate ladder structure formation. This chemical modification ensures that even when single fiber fineness is increased to 0.8-2.1 dtex for higher production output, the resulting carbon fiber bundles maintain superior mechanical properties (strand strength ≥4.9 GPa, strand modulus ≥200 GPa) due to the enhanced structural development during flameproofing.
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 carbon fiber bundles with superior mechanical properties and reduced costs, achieving high strand strength and modulus of elasticity with minimal variability, suitable for use in composite materials.
Implementation Method 1
flameproofing at 200 to 300°C in air or another oxidizing gas atmosphere to make a flameproof fiber bundle
Implementation Method 2
carbonizing this at 800 to 2,000°C in an inert gas atmosphere such as nitrogen or argon
Data Source
AI summary
Provided are carbon fibers which have a thicker single fiber fineness of the polyacrylonitrile-based precursor fiber bundles and lower production costs, and which have excellent mechanical properties. Also provided are: carbon fiber bundles having a single fiber fineness of 0.9-2.1 dtex, a strand strength of 4.9 GPa or greater, and a strand elastic modulus of 200 GPa or greater; carbon fiber bundles having a single fiber fineness of 0.9-2.5 dtex, a strand strength of 3.0 GPa or greater, and a strand elastic modulus of 240 GPa or greater; and an optimal method for producing said carbon fiber bundles. carbon fiber bundles having a single fiber fineness of 0.9-2.5 dtex, a strand strength of 3.0 GPa or greater, and a strand elastic modulus of 240 GPa or greater; and an optimal method for producing said carbon fiber bundles.