Nozzle Array with Gas Shrouding for Fine Cellulose Fiber Extrusion

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Solution Overview

Problem

Current methods are unable to economically produce cellulose fibers with diameters less than 15 microns at high throughput rates, and fail to extrude multiple filaments per linear centimeter at desired production speeds without damaging the spinnerette, especially at back pressures above 20 bar.

Innovation Solution

An array of nozzles with uniquely shaped cross-sectional configurations and pressurized gas shrouding systems that allow for the extrusion of cellulose fibers with diameters less than 15 microns at throughputs greater than 0.1 grams/hole/minute and production speeds up to 750 meters per minute, using a die block/spinnerette assembly that includes hollow cylindrical tubes and strategically positioned pressurized gas conduits to prevent filament adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional extrusion methods are used, then production process is simple, but cellulose fiber diameter cannot be reduced below 15 microns at economically feasible throughput

Engineering Contradiction:

Improvecellulose fiber diameterVSAvoidthroughput

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The extrusion system is segmented into multiple independent nozzles arranged in an array, each capable of extruding fine filaments. The die block contains a plurality of nozzles that can be independently configured, allowing each nozzle to produce fibers of precise diameter while the collective array achieves high throughput through parallel production

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each nozzle in the array is designed with specific local characteristics including unique cross-sectional configurations and individual pressurized gas shrouding. This local customization allows precise control over filament diameter and shape at each extrusion point while maintaining overall system productivity

Inventive Principle:

Principle #3Local quality

2Productivity

If production speed is increased to 750 meters per minute, then productivity improves, but spinnerette is damaged due to back pressures above 20 bar

Engineering Contradiction:

Improveproduction speedVSAvoidspinnerette durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Pressurized gas is introduced through conduits positioned near each nozzle to provide shrouding protection for the extruded filaments. This pneumatic system allows the spinnerette to operate at high back pressures (above 20 bar) required for high-speed production without direct mechanical stress on the nozzle structure, as the gas cushion protects the filaments and reduces frictional forces

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The system combines multiple materials and functions in the die block assembly, including the nozzle material, pressurized gas medium, and coating materials on the spinnerette surface. This composite approach allows the system to withstand high back pressures while maintaining nozzle integrity and filament quality at production speeds up to 750 meters per minute

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If multiple filaments are extruded per linear centimeter, then fiber fineness increases, but filament adhesion occurs without effective shrouding

Engineering Contradiction:

Improvefiber finenessVSAvoidfilament adhesion

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

Pressurized gas acts as an intermediary medium between the extruded filaments and the surrounding environment. The gas shrouding creates a protective barrier that prevents direct contact between adjacent filaments, eliminating adhesion while allowing the extrusion of multiple fine filaments per linear centimeter. The gas flow pattern is specifically designed to maintain separation without interfering with filament formation

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If throughput is increased to greater than 0.1 grams/hole/minute, then productivity improves, but fiber diameter control becomes difficult

Engineering Contradiction:

ImprovethroughputVSAvoidfiber diameter control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system incorporates dynamic control elements including adjustable pressurized gas flow rates and configurable nozzle parameters. The pressurized gas shrouding can be dynamically adjusted to compensate for variations in throughput, maintaining consistent fiber diameter control even at high throughput rates greater than 0.1 grams/hole/minute. The array configuration allows dynamic load distribution across multiple nozzles

Inventive Principle:

Principle #15Dynamics

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

Enables the production of high-quality, fine cellulose fibers with diameters as low as 5 microns at increased throughput rates and speeds, preventing filament adhesion and ensuring efficient solvent removal, thus forming a non-woven web with improved properties.

Implementation Method 1

Each of the first openings is capable of emitting a pressurized gas which surrounds one of the extruded molten filaments

Methodology Applied

Scientific EffectGas shrouding:

Implementation Method 2

Each of the second openings is capable of emitting a pressurized gas stream essentially parallel to the longitudinal central axis of each of the nozzles which functions to shrouds each of the extruded molten filaments

Methodology Applied

Scientific EffectGas stream shrouding:

Implementation Method 3

The molten filaments are then contacted with a liquid which causes a major portion of the solvent to solvate into the liquid solution and thus allows the molten filaments to coagulate into solid cellulose fibers

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 4

the molten filaments to coagulate into solid cellulose fibers

Methodology Applied

Scientific EffectCoagulation: Coagulation

Implementation Method 5

Each method utilizes special equipment to heat the aqueous solution and extrude it through a die block assembly

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 6

The aqueous solution is usually extruded in a downward direction such that the pressurized gas and gravity will cause the aqueous solution to attenuate into a plurality of molten filaments

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentUS8029259B2Array of nozzles for extruding multiple cellulose fibers

Publication Date: 2011.10.04 REIFENHAUSER GMBH & CO MASCHFAB

AI summary

An array of nozzles is disclosed for forming multiple cellulose fibers. Each nozzle has a longitudinal central axis and includes a tube with a cross-section having a diameter through which an aqueous solution of cellulose and a solvent can be extruded into a molten filament. A first opening is present which surrounds each of the tubes. The first opening has a cross-section with a diameter, and each of the first openings is capable of emitting a pressurized gas which surrounds one of the extruded molten filaments. At least three second openings are spaced away from each of the first openings. Each of the second openings is capable of emitting a pressurized gas stream essentially parallel to the longitudinal central axis of each of the nozzles, and each of the pressurized gas streams functions to shroud one of the extruded molten filaments.