Coagulation Bath Inlet Design for Fiber Fibrillation Control
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Solution Overview
Problem
Existing spinning processes face challenges in controlling fiber properties such as fibrillation and swelling, particularly due to the high cost and inefficiency of solvents like NMMO, and the complexity of maintaining consistent coagulation conditions in precipitation baths.
Innovation Solution
A coagulation bath design with a coagulation liquid inlet positioned beneath the liquid surface, allowing fresh coagulation liquid to flow against the shaped articles, creating controlled coagulation conditions that reduce fibrillation and enable precise solvent management, including the use of multiple baths for staged coagulation and solvent recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the shaped articles are introduced directly into a precipitation bath with the liquid surface at the entry level, then the coagulation process is simple, but the coagulation conditions cannot be controlled precisely and fibrillation occurs
Solution Approach 1:
The precipitation bath is divided into multiple zones: an entry region where shaped articles are introduced, a coagulation region with liquid inlet mouths positioned below the liquid surface, and an overflow region. This segmentation allows different functions in different regions, enabling precise control of coagulation conditions while maintaining a relatively simple overall structure.
Solution Approach 2:
Fresh coagulation liquid acts as an intermediary medium that flows from the inlet mouths (positioned below the liquid surface) upward through the coagulation region, creating controlled coagulation conditions for the shaped articles without requiring direct introduction at the liquid surface.
2Manufacturing precision
If fresh coagulation liquid is introduced at the liquid surface level, then the bath structure is simple, but the coagulation liquid does not flow against the shaped articles effectively, resulting in poor fibrillation control
Solution Approach 1:
Instead of introducing fresh coagulation liquid at the liquid surface level (conventional approach), the liquid inlet mouths are positioned below the liquid surface level. This inversion allows the fresh liquid to flow upward against the shaped articles, creating effective coagulation control and reducing fibrillation.
3Manufacturing precision
If the coagulation liquid inlet is positioned below the liquid surface, then coagulation conditions are controlled precisely and fibrillation is reduced, but the device structure becomes more complex
Solution Approach 1:
The liquid inlet mouths are strategically positioned in specific locations below the liquid surface within the coagulation region, creating localized zones of controlled coagulation. This local quality approach ensures precise fiber quality consistency without requiring complex system-wide modifications.
4Loss of substance
If conventional precipitation baths are used without staged coagulation, then the process is simple, but solvent recovery and management are inefficient
Solution Approach 1:
The precipitation process is segmented into multiple stages with separate baths: a first precipitation bath for initial coagulation and a second precipitation bath for further treatment. This segmentation enables efficient solvent recovery and management in each stage, reducing overall solvent loss while avoiding the need for a single complex integrated system.
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 enhances the consistency and quality of the fibers by controlling coagulation conditions, reducing fibrillation, and optimizing solvent usage, leading to improved textile properties and cost efficiency.
Implementation Method 1
This occurs by precipitation of the extrudates in water or diluted amine oxide solutions once the extrudates of the extrusion die are guided via an air gap into the precipitation bath.
Data Source
AI summary
A coagulation bath is provided with a coagulation liquid inlet, wherein the coagulation liquid inlet has one or more mouths, which are arranged beneath the coagulation liquid level of the coagulation bath; in particular a spinning bath system with a coagulation liquid inlet and an entry region for spinning yarns which are solidified in the spinning bath, wherein the entry region is provided at a position in which, when the spinning bath is filled with coagulation liquid, the liquid surface is the surface of the coagulation liquid, the coagulation liquid inlet has one or more mouths arranged beneath the entry region and are directed to spinning yarns introduced into the spinning bath such that fresh coagulation liquid flows against the spinning yarns during operation, and optionally a liquid fill level regulator and possibly further tanks with different coagulation liquid composition and methods for spinning yarns in a spinning bath.