Multizone Electroblowing Process for Fiber Size and Throughput
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Solution Overview
Problem
The electroblowing process faces a challenge in simultaneously achieving smaller fiber sizes and increased maximum process throughput, as conventional methods allow for only one goal at the expense of the other, due to the competing effects of spinning and drying temperatures.
Innovation Solution
The process involves a spin cell with at least two zones, where the first zone is maintained at a relatively low temperature and the second zone is significantly warmer, allowing the polymer stream to pass through both zones, with controlled temperature differences and residence times to optimize fiber formation and solvent evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature is increased to increase throughput, then the production rate improves, but the fiber size increases (becomes larger than desired)
Solution Approach 1:
The drying chamber is divided into two distinct zones: a first zone with lower temperature (20-40°C) for fiber formation and attenuation, and a second zone with higher temperature (45-270°C) for rapid solvent evaporation. This segmentation allows independent optimization of each zone's temperature for its specific function, resolving the contradiction between producing small fibers and achieving high throughput.
Solution Approach 2:
Different temperature conditions are applied to different spatial regions of the process. The first zone maintains cooler conditions suitable for fiber attenuation and formation, while the second zone provides heated conditions for rapid drying. This local quality approach enables simultaneous achievement of small fiber size and high production rate by matching local conditions to local requirements.
2Length of moving object
If the temperature is decreased to reduce fiber size, then the fiber diameter decreases, but the solvent evaporation rate decreases (reducing throughput)
Solution Approach 1:
The drying chamber is divided into two distinct zones: a first zone with lower temperature (20-40°C) for fiber formation and attenuation, and a second zone with higher temperature (45-270°C) for rapid solvent evaporation. This segmentation allows independent optimization of each zone's temperature for its specific function, resolving the contradiction between producing small fibers and achieving high throughput.
Solution Approach 2:
The first zone performs the preliminary action of fiber attenuation and formation at lower temperature before the polymer stream enters the second zone for rapid drying. This preliminary action prepares the fibers for subsequent high-speed evaporation, enabling small fiber size to be achieved without sacrificing overall throughput.
3Manufacturing precision
If the residence time in the first zone is increased to improve fiber formation, then fiber attenuation improves, but the overall process time increases
Solution Approach 1:
The process optimizes residence time parameters for each zone: the first zone uses short residence time (0.1-10 milliseconds) sufficient for fiber attenuation, while the second zone uses longer residence time (1-20 times that of zone 1) for complete solvent evaporation. This parameter optimization ensures high-quality fiber formation without unnecessary time loss, as each zone's residence time is tailored to its specific function.
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 approach enables the production of smaller fibers without sacrificing throughput, by reducing solvent evaporation in the cooler zone and promoting rapid drying in the hotter zone, thus decoupling the effects of temperature on fiber size and throughput.
Implementation Method 1
The charge on the fibers can be induced by the presence of a strong electric field near the spinneret
Implementation Method 2
evaporating solvent and depositing the polymer fibers onto a collector
Implementation Method 3
reducing solvent evaporation in the cooler zone and promoting rapid drying in the hotter zone
Data Source
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AI summary
Methods and apparatuses are provided for producing fibers via electroblowing. In an embodiment of the present invention, a polymer stream, formed from a spinning nozzle, passes through a first temperature zone for a first residence time, and subsequently passes through a second temperature zone for a second residence time, where the second zone has a higher average temperature than the first zone. In an embodiment of an apparatus of the present invention, the apparatus has a region between the spinning nozzle outlet and collector that includes at least two zones through which a polymer stream passes, where the second zone has a higher average temperature than the first zone.