MPD-I Yarn Low Shrinkage Continuous Spinning
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Solution Overview
Problem
Current methods for producing meta-aramid fibers require separate and time-consuming steps for spinning and solvent removal, leading to a batch process instead of continuous production due to the formation of a chemical complex between the solvent and salt, which hinders rapid solvent removal and subsequent fiber drawing.
Innovation Solution
A high-speed dry spinning process involving extrusion of a polymer solution into a gaseous medium, followed by quenching and conditioning with aqueous solutions of varying solvent and salt concentrations, allows for immediate drawing and subsequent washing, drying, and heat treatment in a continuous process, effectively removing solvent and stabilizing the fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fiber is spun from a solution containing polymer, solvent, and salt, then the fiber formation is achieved, but the solvent removal is complicated by chemical complex formation between salt and solvent
Solution Approach 1:
The patent applies preliminary action by removing a significant portion of the solvent through evaporation during the high-speed spinning process itself, before the fiber enters the washing and drawing stage. This preliminary solvent removal prevents excessive complex formation between salt and solvent, simplifying subsequent processing while maintaining fiber formation quality.
2Reliability
If long processing times are used for solvent removal and fiber drawing, then adequate mass transfer of solvent is achieved, but the production rate decreases
Solution Approach 1:
The patent merges the high-speed spinning process with immediate solvent removal and drawing operations into a coupled continuous process. The fiber is spun, drawn, and washed in an integrated sequence without interruption, eliminating the need for separate batch processing stages while ensuring complete solvent removal through the coordinated action of evaporation, washing, and drawing.
Solution Approach 2:
The patent implements continuity of useful action by maintaining an uninterrupted continuous process where fiber formation, solvent removal, and drawing occur in seamless succession. The high-speed spinning is directly coupled with the washing and drawing sections, ensuring that the fiber continuously progresses through all processing stages without stopping or batch transitions, thereby maximizing productivity while maintaining reliability.
3Productivity
If the spinning and drawing processes are coupled together, then production efficiency increases, but the process control becomes more difficult due to rapid solvent removal requirements
Solution Approach 1:
The patent applies segmentation by dividing the coupled process into distinct functional sections: a high-speed spinning section with rapid evaporation, followed by a washing section, and then a drawing section. Each section is optimized for its specific function and can be independently controlled, making the overall high-speed coupled process easier to manage while maintaining high productivity.
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 process enables the production of meta-aramid fibers with improved thermal stability and coloration properties, achieving thermal shrinkage of 0.4% or less at 285°C and significant dye absorption, while maintaining mechanical strength and allowing for continuous production.
Implementation Method 1
The gaseous medium evaporates at least 25% of the solvent in the fiber
Implementation Method 2
The fiber is then quenched in an aqueous quenching solution having a first concentration of solvent, salt and water and at a first temperature
Implementation Method 3
heat treated by heating the fiber above the glass transition temperature of the fiber
Data Source
AI summary
The invention relates a heat-treated poly(metaphenylene isophthalamide) polymer fiber having a crystalline structure as represented by a carbonyl stretch peak at a wavelength of 1,650 cm−1 in a Raman spectra response which before coloration with a dye, shrinks linearly 0.4 percent or less when exposed to 285 degrees Centigrade for 30 minutes; and which after contact with an aqueous red dye solution for 1 hour at 120 degrees Centigrade, has an “L” value coloration of at least 40 units lower than the “L” value of the fiber before coloration.