Carbon Fiber Precursor Bundle with Low Intermingle
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Solution Overview
Problem
Current methods for producing carbon fibers face challenges such as excessive heat storage during flame retarding treatment, leading to yarn breaking and fusion bonding, which degrades the quality and increases production costs, and existing large tow carbon fibers do not achieve sufficient strength and elastic modulus comparable to small tow carbon fibers.
Innovation Solution
A carbon fiber precursor fiber bundle with a low degree of intermingle between small tows, consisting of substantially straight fibers with low moisture content, and a widthwise dividing capability to divide into small tows during the firing step, using air flow intermingling to maintain a single tow form and suppress heat storage, along with specific monofilament and oiling agent properties to enhance strength and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of the fiber tow is increased to improve productivity, then production efficiency is improved, but excessive heat storage occurs during flame retarding treatment causing yarn breaking and fusion bonding
Solution Approach 1:
The fiber bundle is divided into multiple small tows (each with 3,000 to 20,000 filaments) that are weakly intermingled at their selvages. This segmentation allows each small tow to be treated independently during flame retarding, preventing heat accumulation while maintaining the overall bundled structure for efficient handling and high productivity.
Solution Approach 2:
The small tows are pre-intermingled at their selvages to form a bundled fiber bundle before the flame retarding treatment. This preliminary action creates a structure that maintains tow form during handling but allows easy division into small tows during firing, enabling thick bundles to be processed without excessive heat storage.
2Object-affected harmful factors
If the fiber tow is divided into small tows to suppress heat storage, then heat storage is reduced, but the complexity of the production process increases
Solution Approach 1:
Multiple small tows are merged into a bundled fiber bundle through weak intermingling at selvages. This combining allows the tows to be handled as a single unit during high-speed spinning and winding, simplifying the production process while maintaining the ability to divide into small tows during flame retarding to suppress heat storage.
Solution Approach 2:
The bundled fiber bundle automatically divides into individual small tows during the flame retarding treatment due to the weak intermingling structure. This self-service division eliminates the need for complex dividing mechanisms, reducing process complexity while effectively suppressing heat storage.
3Stability of the object's composition
If crimp imparting is used to maintain tow form, then tow stability is improved, but the degree of intermingle increases causing difficulty in division and potential yarn breaking
Solution Approach 1:
The intermingling is applied locally only at the selvages of the small tows rather than throughout the entire tow. This local quality approach maintains tow form stability for handling while keeping the degree of intermingle low (1 m⁻¹ or less), allowing easy division during flame retarding without causing yarn breaking.
4Stability of the object's composition
If moisture content is increased to maintain tow form without crimp, then tow stability is improved, but heat storage during flame retarding increases
Solution Approach 1:
The dependency on moisture for maintaining tow form is extracted and replaced by the weak intermingling structure at selvages. This allows the moisture content to be reduced to less than 10% by mass, thereby reducing heat storage during flame retarding while maintaining tow form stability through the structural arrangement rather than moisture content.
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 allows for easy division of the fiber bundle into small tows during flame retarding, reducing heat storage and yarn breaking, resulting in high-quality carbon fibers with improved strength and productivity while maintaining low production costs.
Implementation Method 1
using air flow intermingling to maintain a single tow form and suppress heat storage
Implementation Method 2
the precursor fiber is heated in an oxidative atmosphere set at 200 to 350° C. The flame retarding treatment generates a reaction heat
Implementation Method 3
heat tends to be stored inside the fiber tow
Data Source
AI summary
A production method for a carbon fiber precursor fiber bundle and a production apparatus of the carbon fiber precursor fiber bundle. A carbon fiber precursor fiber bundle that has a degree of intermingle of 1 m−1 or less between small tows, consists of substantially straight fibers without imparted crimp, a tow of which straight fibers has a moisture content of less than 10% by mass when housed in a container, and has a widthwise dividing capability to maintain a form of a single aggregate of tows when housed in a container, taken out from the container and guided into a firing step, and to divide into a plurality of small tows in the firing step by the tension generated in the firing step.