Continuous Polyimide Fiber Production via Solvent Parameter Change
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Solution Overview
Problem
Current methods for producing polyimide fibers face challenges such as the use of toxic solvents in one-step processes and performance deterioration in two-step processes, making them unsuitable for continuous industrial production and environmentally friendly manufacturing.
Innovation Solution
A method involving the reaction of diamines and dianhydrides to form a polyamic acid solution, followed by filtration, defoaming, spinning, coagulation, drying, and multi-segment thermal treatment and stretching in a tubular heating furnace to produce high-quality polyimide fibers suitable for continuous industrial production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a one-step process is used to prepare polyimide fibers from polyimide solution, then the spinning process is simple, but the residual solvent in fibers cannot be completely removed due to high toxicity and high boiling point of phenol-based solvents
Solution Approach 1:
The patent changes the solvent parameter from phenol-based (high boiling point, toxic) to aliphatic carboxylic acid-based (lower boiling point, less toxic). This parameter change enables complete solvent removal while maintaining spinning process simplicity, resolving the contradiction between ease of manufacture and harmful factors.
2Object-affected harmful factors
If a two-step process is used to prepare polyimide fibers from polyamic acid solution, then residual solvent content is reduced, but the properties of polyamic acid fibers deteriorate over time and multiple steps make it unsuitable for continuous production
Solution Approach 1:
The patent merges the polyamic acid fiber formation and polyimide fiber formation steps into a single continuous process. The polyamic acid solution is spun, coagulated, and thermally treated in one continuous operation, eliminating the need for separate steps and intermediate storage, thus enabling continuous production while maintaining low residual solvent content.
Solution Approach 2:
The patent implements continuous production by maintaining continuous flow of polyamic acid solution through spinning, coagulation, and thermal treatment stages. This continuous operation prevents property deterioration that occurs in batch two-step processes and enables industrial-scale production.
3Quantity of substance
If polyamic acid fibers are wound and stored, then small amount of residual solvents become nonvolatile and affect storage and performance
Solution Approach 1:
The patent extracts and removes residual solvents completely during the thermal treatment stage before fiber winding and storage. By using lower boiling point solvents and extended thermal treatment, all residual solvents are evaporated and removed, preventing them from becoming nonvolatile and affecting storage performance.
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 method enables the production of high-performance polyimide fibers with improved imidization and orientation, facilitating mass production while minimizing environmental impact and simplifying the synthetic process.
Implementation Method 1
reacting a diamine and a dianhydride in a solvent to obtain a polyamic acid solution
Implementation Method 2
filtering the polyamic acid solution
Implementation Method 3
spinning the defoamed polyamic acid solution to obtain polyamic acid fibers
Implementation Method 4
coagulating polyamic acid fibers in a solvent
Implementation Method 5
drying polyamic acid fibers
Implementation Method 6
treating and stretching the dried polyamic acid fibers in a tubular heating furnace having at least three furnace segments
Implementation Method 7
treating and stretching the dried polyamic acid fibers in a tubular heating furnace
Data Source
AI summary
Methods for making high quality polyimide fibers suitable for continuous industrial production are described. Polyimide fibers are continuously prepared from a polyamic acid solution through sequentially spinning the polyamic acid solution by either a wet or a dry-wet process, coagulating, drying or drying after washing, thermally treating and stretching the resulting polyamic acid fibers to obtain polyimide fibers, and winding polyimide fibers as prepared into rolls.