Hydroentangled Lyocell Melt-Blown Web Strength via Multi-Step Water Jet
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Solution Overview
Problem
Existing hydroentangled Lyocell melt-blown webs lack sufficient strength for various applications, particularly lightweight products with area weights below 10 g/m2, which limits their usability and performance.
Innovation Solution
A process involving Lyocell melt-blown webs subjected to fine high-pressure water jets in at least three treatment steps, with pressures of 75 bar or less, enhancing the web's strength and properties by improving the hydroentanglement process, and optionally incorporating partial coagulation of filaments before web formation and adding modifying agents or additional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hydroentanglement process is used on Lyocell melt-blown webs, then the web can be bonded, but the resulting product lacks sufficient strength for lightweight applications
Solution Approach 1:
The hydroentanglement process is divided into multiple treatment steps (at least three) with progressively increasing pressures. The first treatment step uses lower pressure (e.g., 20-40 bar) to create initial bonding, while subsequent steps use higher pressures (e.g., 60-100 bar) to enhance bond strength. This segmented approach allows lightweight webs to achieve sufficient strength without requiring excessive single-step pressure that would damage the delicate structure.
Solution Approach 2:
The invention changes the pressure parameter dynamically through multiple treatment steps rather than using a single fixed pressure. Each treatment step uses optimized pressure levels suitable for the specific web weight and desired final strength. This parameter optimization enables lightweight webs (below 10 g/m²) to achieve adequate strength while maintaining their low-weight advantage.
2Strength
If high pressure is used in hydroentanglement to increase web strength, then bonding improves, but energy and water consumption increase
Solution Approach 1:
The hydroentanglement process is segmented into multiple treatment steps with progressively increasing pressures. Instead of applying maximum pressure in a single step (which consumes excessive energy), the process distributes the bonding action across several steps at moderate pressures. This reduces peak energy demands and allows for more efficient water utilization, as each treatment step builds upon previous bonding without requiring complete re-wetting at high pressure.
Solution Approach 2:
The multiple treatment steps create a continuous bonding process where each step builds upon the previous one. The web remains in the hydroentanglement system throughout all treatment steps, eliminating the need for intermediate drying and re-wetting cycles. This continuous action reduces energy consumption by maintaining consistent processing conditions and avoiding repeated heating/cooling cycles.
3Ease of manufacture
If conventional hydroentanglement process is used, then bonding can be achieved, but the process requires drying the web before treatment which increases energy consumption
Solution Approach 1:
The invention merges the Lyocell melt-blown web formation process with the hydroentanglement bonding process into a single integrated operation. The web is subjected to hydroentanglement treatment immediately after formation, while still in the wet state from the coagulation bath. This eliminates the separate drying step that would otherwise be required, significantly reducing energy consumption and simplifying the manufacturing process.
Solution Approach 2:
The hydroentanglement treatment is performed as a preliminary action immediately after web formation, before any drying occurs. By conducting the bonding treatment while the web is still wet and pliable, the process takes advantage of the web's natural state right after manufacturing, eliminating the need for subsequent drying and re-wetting operations.
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
The process significantly enhances the strength of hydroentangled Lyocell melt-blown webs, making them self-supporting and suitable for diverse applications, even at low area weights, while reducing energy and water consumption by integrating hydroentanglement directly into the melt-blown process without prior drying.
Implementation Method 1
the web is subjected to a treatment by fine high-pressure jets of water
Implementation Method 2
contacting said filaments in the air gap with a medium which at least partially coagulates the filaments
Implementation Method 3
collecting and precipitating said filaments in order to form a web
Data Source
AI summary
The present invention relates to a process for the production of a hydroentangled product comprising cellulose fibers, wherein a Lyocell melt-blown web is subjected to a treatment by fine high-pressure jets of water, characterized in thatthe web is subjected to said fine high-pressure jets in at least three treatment stepsthe pressure of said high-pressure jets is 75 bar or less in each of said treatment steps.Furthermore, the invention relates to products obtainable by said products, and uses thereof.