Polyacrylonitrile Copolymer Stabilization for Carbon Fiber Productivity
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Solution Overview
Problem
Existing carbon fiber production technologies face challenges in reducing production costs, achieving high thermal stability, and maintaining the quality of carbon fibers with high single fiber fineness, as they often result in incomplete stabilization, interlacing issues, and decreased productivity.
Innovation Solution
A polyacrylonitrile-based copolymer comprising acrylonitrile, (meth)acrylamide, and hydroxyalkyl unsaturated carboxylate units is used to produce a precursor fiber with high thermal stability, which is then stabilized and carbonized to produce a high-quality carbon fiber bundle with improved productivity and fiber density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the total fineness of fiber bundles is increased to improve productivity and reduce production cost, then productivity and cost reduction are improved, but scorching occurs during stabilization treatment and quality deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by incorporating specific copolymerized components (carboxylic acid groups and hydroxyl groups) in controlled amounts. This modifies the stabilization reaction characteristics, allowing high fineness bundles to be stabilized without scorching, thus enabling productivity improvement while avoiding quality deterioration.
2Productivity
If the stabilizing process is shortened to improve productivity, then productivity is improved, but incomplete stabilization occurs and quality deteriorates
Solution Approach 1:
The patent modifies the chemical parameters of the precursor fiber by copolymerizing monomers that generate carboxylic acid and hydroxyl groups. These functional groups catalyze and control the stabilization reaction, enabling complete stabilization to occur rapidly at lower temperatures, thus shortening the process time while ensuring complete stabilization.
Solution Approach 2:
The patent creates a composite polymer structure combining acrylonitrile units with copolymerized units containing carboxylic acid and hydroxyl groups. This composite structure provides both the necessary mechanical properties and the controlled stabilization reactivity, allowing rapid and complete stabilization without compromising quality.
3Manufacturing precision
If oxygen permeability is improved to control oxygen concentration distribution uniformly, then stabilization uniformity is improved, but the stabilizing process time increases and productivity decreases
Solution Approach 1:
The patent changes the chemical reactivity parameters by incorporating copolymerized units that generate carboxylic acid and hydroxyl groups during stabilization. These groups create localized reaction sites that promote uniform oxygen consumption and reaction progress throughout the fiber cross-section, achieving uniform stabilization rapidly without requiring extended process times.
4Stability of the object's composition
If thermal stability of spinning dope is enhanced by maintaining high temperature, then thermal stability is improved, but gelling occurs and process trouble arises
Solution Approach 1:
The patent changes the chemical composition parameters by copolymerizing monomers that introduce carboxylic acid and hydroxyl groups. These functional groups modify the intermolecular interactions in the spinning dope, preventing excessive molecular association and gelation even at elevated temperatures, thus enhancing thermal stability without causing gelling.
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 results in a carbon fiber bundle with enhanced thermal stability, reduced production costs, and improved productivity, maintaining high tensile strength and elastic modulus while preventing the formation of double cross-section structures.
Implementation Method 1
a dramatic enhancement in thermal stability is achieved when a spinning dope is maintained at a high temperature of about 80° C., by esterifying methacrylic acid which is a component for accelerating a stabilizing reaction of a polymer
Implementation Method 2
heating a precursor fiber bundle composed of the polyacrylonitrile-based precursor fiber for carbon fiber in an oxidizing atmosphere
Implementation Method 3
heating the stabilized fiber bundle obtained by the method for producing a stabilized fiber bundle, in an inert gas at a temperature of from 800° C. to 2000° C.
Data Source
AI summary
Provided are: a polyacrylonitrile-based precursor fiber for the production of a carbon fiber having a large single-fiber fineness, said precursor fiber ensuring high heat stability of a spinning dope and excellent productivity; and a copolymer suitable for the production of said precursor fiber. Also provided are: high-quality carbon fiber bundles which have a large single-fiber fineness and excellent productivity; a process for producing the same; and a process for producing flameproofed fiber bundles suitable for the production of the carbon fiber bundles. A polyacrylonitrile-based copolymer which comprises 93.0 to 99.4 mol % of acrylonitrile units, 0.5 to 4.0 mol % of (meth)acrylamide-based units, and 0.1 to 3.0 mol % of unsaturated carboxylic acid hydroxyalkyl ester units and in which the (meth)acrylamide-based units are (meth)acrylamide units and/or (meth)acrylamide derivative units having a molecular weight of 105 or less; a precursor fiber comprising the copolymer; a process for producing flameproofed fiber bundles which uses precursor fiber bundles consisting of the precursor fiber; carbon fiber bundles; and a process for production thereof.