Cellulose Filament Deflection Width Control for Friction Reduction
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Solution Overview
Problem
In the lyocell method for producing cellulose filaments, high frictional loads during the drawing process cause filament damage and entanglement issues due to the use of rigid deflection devices, leading to reduced productivity and spinning speeds.
Innovation Solution
A method and device that minimize frictional loads on filaments by controlling the deflection width of the filament bundle using the formula L > (2*LZ*cos(B/2)*v^2.5)/(10*ccell^0.5*Q), where L is the deflection width, LZ is the number of extrusion openings, B is the deflection angle, v is the drawing speed, ccell is the cellulose concentration, and Q is a dimensionless load number, to maintain minimal friction and prevent entanglements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rigid deflection devices are used in the drawing process, then the filaments can be deflected and processed, but high frictional loads cause filament damage and entanglement
Solution Approach 1:
A liquid medium (coagulation bath) is introduced as an intermediary between the filament bundle and the deflection device. The filaments are deflected while immersed in this liquid, which acts as a lubricant to minimize frictional loads and prevent filament damage and entanglement during the drawing process
Solution Approach 2:
The patent utilizes a hydraulic/liquid-based system where the coagulation bath provides a liquid environment for filament deflection. This liquid medium reduces direct contact friction between the filaments and the deflection device, enabling smoother operation with lower frictional loads
2Productivity
If high drawing speeds are used to increase productivity, then output increases, but frictional loads and filament damage increase
Solution Approach 1:
The liquid coagulation bath serves as a mediator that enables high-speed drawing operations by continuously lubricating the filaments during deflection. This reduces frictional heating and damage that would otherwise limit maximum drawing speeds
Solution Approach 2:
The patent changes the physical state and environment parameters by immersing filaments in a liquid medium during deflection, rather than using dry mechanical contact. This parameter change allows for higher operating speeds while maintaining filament integrity
3Stability of the object's composition
If strong bundling is applied to consolidate filaments, then handling improves, but normal forces on contact filaments increase causing damage
Solution Approach 1:
The liquid medium acts as a cushioning intermediary that distributes and reduces the normal forces exerted on filaments during bundling and deflection. This prevents the high contact forces from causing filament breakage while still achieving strong bundle consolidation
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 allows for higher productivity and spinning speeds by reducing filament damage and entanglements, enabling the use of larger deflection widths and maintaining filament stability during the drawing process.
Implementation Method 1
solidifying the filaments in a coagulation bath
Implementation Method 2
transferred the extrudates from the extruder into the precipitation bath via a gas gap
Data Source
AI summary
A method for producing solid cellulose filaments from a fluid of the cellulose by extruding the fluid through a plurality of extrusion openings, whereby fluid filaments are produced, and solidifying the filaments in a coagulation bath, the filaments being bundled in the coagulation bath and being deflected as a bundle in order to be drawn from the coagulation bath above the coagulation bath level, the bundle of filaments assuming a deflection width on a deflecting device, which deflection width is defined in accordance with a formula. A device therefor is also provided.