Hydroentangled Cellulose Web Bonding Process
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Solution Overview
Problem
Existing nonwoven web production methods, such as Lyocell melt-blowing, face limitations in achieving bonded webs with optimal properties and efficiency, particularly in terms of web stability and processing convenience.
Innovation Solution
Combining the Lyocell melt-blowing process with a hydroentanglement step, where cellulose fibers are extruded, drawn by a gaseous stream, and then bonded using a hydroentanglement process, allowing for the production of stable lightweight webs with enhanced properties and synergistic effects, including reduced energy and water usage by processing the web in a never-dried state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If Lyocell melt-blowing process is used to produce nonwoven webs, then lightweight webs can be produced, but the webs lack sufficient bonding strength and stability
Solution Approach 1:
The patent combines the Lyocell melt-blowing process with a hydroentanglement process in a single integrated production line. The melt-blown web is directly subjected to hydroentanglement treatment without intermediate drying or handling steps, merging two previously separate processes into one continuous operation that produces both lightweight and strongly bonded webs
Solution Approach 2:
The patent changes the physical state parameters of the web by maintaining it in a never-dried, moist state throughout the processing. This parameter change enables the hydroentanglement process to work more effectively on the gel-like cellulose structure, achieving superior bonding while preserving light weight
2Productivity
If filaments are collected and precipitated to form a web, then a continuous nonwoven structure is obtained, but energy is consumed for drying the web
Solution Approach 1:
The patent performs the bonding action (hydroentanglement) before the web would normally be dried. By applying the high-pressure water jet treatment to the never-dried web, the bonding is established in advance, eliminating the need for subsequent drying operations and the associated energy consumption
Solution Approach 2:
The patent maintains continuous processing by eliminating the drying step between web formation and bonding. The web transitions directly from the precipitation bath to the hydroentanglement treatment in a continuous flow, maintaining moisture throughout and avoiding energy-intensive intermittent drying operations
3Ease of operation
If filaments are treated with coagulating medium in air gap, then softness and textile-like performance are improved, but filaments become sticky and difficult to process
Solution Approach 1:
The patent uses a specifically formulated coagulating medium containing sulfuric acid and sodium sulfate that acts as an intermediary substance. This medium promotes controlled coagulation of the cellulose filaments in the air gap, achieving the desired softness and textile-like properties while the subsequent rapid washing removes excess coagulating agents that would cause stickiness
Solution Approach 2:
The patent rapidly transitions the web through the coagulation and washing stages, rushing through the process before stickiness can develop. The quick passage through the precipitation bath and immediate high-pressure washing prevents the filaments from becoming excessively sticky while still achieving the softness benefit
4Stability of the object's composition
If web is dried before hydroentanglement, then processing stability is improved, but water consumption and energy usage increase
Solution Approach 1:
The patent changes the stability parameter by demonstrating that the never-dried web, despite being moist, can be successfully processed through hydroentanglement. The high-pressure water jet treatment provides sufficient stabilization during bonding without requiring prior drying, altering the traditional parameter requirement
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 results in bonded cellulose fiber webs with improved softness and textile-like performance, reduced stickiness, and energy savings, while also serving as an efficient washing step, enabling the production of lightweight, versatile nonwoven products suitable for various applications.
Implementation Method 1
extruded threads of the cellulose solution in NMMO are picked up by a gas stream flowing in a generally parallel direction to the path of the filaments. The cellulose solution, which is ejected through the orifices, is formed to liquid strands or latent filaments, which are drawn (or significantly decreased in diameter and increased in length) by the gas stream
Implementation Method 2
contacting said filaments in the air gap with a medium which at least partially coagulates the filaments
Implementation Method 3
By way of step (b'), the filaments are at least partly precipitated before forming a web
Implementation Method 4
bonding said web by means of a hydroentanglement process
Data Source
AI summary
The present invention relates to a process for the production of a hydroentangled product comprising cellulose fibers, comprising the steps of (a) extruding a solution comprising cellulose dissolved in an aqueous tertiary amine-oxide through a spinneret into an air gap, thereby forming filaments (b) drawing said filaments by means of a gaseous stream, (c) collecting and precipitating said filaments in order to form a web, (d) bonding said web by means of a hydroentanglement process, (e) contacting said filaments in the air gap with a medium which at least partially coagulates the filaments. Furthermore, the invention relates to products obtainable by said products, and uses thereof.