Carbon Fiber Precursor Bundle High Density Part Thermal Oxidation
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Solution Overview
Problem
The existing methods for producing carbon fiber bundles face challenges in ensuring that the connection parts between fiber bundles can smoothly pass through both the flame resistance impartation and carbonization steps, which involve high heating temperatures and process tensions, leading to potential heat generation and breakage issues.
Innovation Solution
A carbon fiber precursor acrylic fiber bundle with a high density part, achieved through a thermal oxidation treatment that forms a region with a maximum fiber density of 1.33 g/cm3 or higher, and a thermal oxidation oven with high and low temperature heating parts, along with a process that includes entanglement treatments and controlled heating, to facilitate smooth passage through both steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flame resistance impartation treatment is performed on the end of a carbon fiber precursor acrylic fiber bundle, then the end becomes flame resistant, but the density of the treated end becomes low (1.30 g/cm³) causing heat generation and difficulty in passing through the treatment step
Solution Approach 1:
The invention applies preliminary flame resistance impartation treatment to the ends of precursor yarns before connecting them to form a fiber bundle. This preliminary treatment ensures that the connection parts have adequate flame resistance properties before the high-temperature carbonization process, preventing thread breaking caused by accumulated heat during subsequent treatments.
Solution Approach 2:
The invention applies flame resistance treatment selectively only to the end portions of the precursor yarns (approximately 10-50 cm from the end) rather than the entire fiber bundle. This local treatment provides flame resistance where needed (at connection points) while minimizing the overall treated volume and associated density reduction effects.
2Reliability
If the fiber bundle is subjected to high heating temperature and high process tension during flame resistance impartation, then the treatment is effective, but the connection part between fiber bundles generates heat and the fiber bundle cannot pass smoothly
Solution Approach 1:
The connection parts are preliminarily treated with flame resistance impartation before the main carbonization process. This preliminary treatment reduces the oxidation reactivity of the connection parts, allowing them to withstand the high heating temperatures and process tensions of subsequent treatments without generating excessive heat or breaking.
Solution Approach 2:
The invention changes the physical and chemical parameters of the connection parts through preliminary flame resistance treatment, specifically reducing their oxidation reactivity and modifying their thermal properties. This allows the connection parts to withstand high-temperature treatment without the heat generation and breakage problems that occur with untreated connections.
3Reliability
If elongation rate is lowered to enable smooth passage through flame resistance impartation and carbonization steps, then breakage is prevented, but high speed production cannot be achieved
Solution Approach 1:
The connection parts are preliminarily treated to enhance their strength and flame resistance properties before the main production process. This preliminary strengthening allows the fiber bundle to withstand the high process tensions of high-speed production without breaking, eliminating the need to reduce elongation rates for breakage prevention.
Solution Approach 2:
The invention changes the physical parameters of the connection parts through preliminary treatment, specifically increasing their tensile strength and thermal stability. These parameter changes enable the connection parts to withstand the mechanical stresses of high-speed production, allowing high elongation rates to be used for increased productivity without sacrificing reliability.
4Productivity
If conventional connection methods are used to connect precursor yarns, then continuous supply to calcination step is achieved, but thread breaking occurs during calcination due to accumulated heat at connection parts
Solution Approach 1:
The invention applies preliminary flame resistance impartation treatment to the ends of precursor yarns before connecting them. This preliminary treatment modifies the connection parts to have reduced oxidation reactivity and enhanced thermal stability, preventing the accumulated heat and thread breaking that occur during subsequent calcination steps while maintaining continuous supply capability.
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 high density part allows for stable and efficient passage through both the flame resistance and carbonization steps, reducing the risk of breakage and enabling high-speed production while maintaining the quality of the carbon fiber bundle.
Implementation Method 1
a method of using a yarn obtained by performing a flame resistance impartation treatment (thermal oxidization treatment) of a rear end of a precursor yarn
Implementation Method 2
a thermal oxidation oven for obtaining the carbon fiber precursor acrylic fiber bundle
Data Source
AI summary
A carbon-fiber-precursor acrylic fiber bundle which can smoothly pass through a flame-resistance impartation step and a carbonization step. The carbon-fiber-precursor acrylic fiber bundle has a high-density part as a portion thereof, wherein the high-density part satisfies the following requirements (A) and (B). Requirement A: The high-density part has a maximum fiber density ρmax of 1.33 g/cm3 or higher. Requirement B: The portion extending between an intermediate-density point and a maximum-density-region arrival point has an increase in fiber density of 1.3×10−2 g/cm3 or less per 10 mm of the fiber bundle length.