Hydroentangled Cotton Fiber Layers to Prevent Delamination
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Solution Overview
Problem
Existing absorbent fibrous products made from hydrophilic cotton fibers face issues with delamination and loss of thickness due to inadequate cohesion, particularly when subjected to conventional bleaching and rinsing processes, which compromise their mechanical resistance and volume.
Innovation Solution
A fibrous product comprising at least 50% hydrophilic cotton fibers with a hydrobonded nonwoven first layer and a second layer of fibers more weakly bonded, bonded by adhesion to each other's surfaces, achieving a decohesion force of at least 0.1 N and tensile strength of 1 N/25mm, primarily through hydroentangled fabric (HEF) bonding without chemical or thermally activated adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bleaching and rinsing processes are used on hydrophilic cotton fibers, then the fibers are cleaned and treated, but the mechanical resistance and volume are compromised
Solution Approach 1:
The patent applies hydroentanglement treatment to the cotton fiber web before bleaching and rinsing operations. This preliminary action creates a hydrobonded nonwoven structure that provides mechanical resistance and cohesion, preventing delamination and thickness loss during subsequent processing steps. The hydroentangled fabric serves as a pre-established framework that protects the fibers during conventional treatment processes.
2Strength
If hot-melt fibers are mixed with cotton to provide cohesion, then the web gains binding strength, but chemical binders are introduced into the product
Solution Approach 1:
The patent replaces chemical or thermal binding systems with a mechanical-hydrodynamic system. High-pressure water jets create hydrobonds between cotton fibers through mechanical entanglement and hydrogen bonding, eliminating the need for hot-melt fibers or chemical adhesives. This mechanical substitution maintains cohesion while avoiding harmful chemical substances in the final product.
3Strength
If high pressure water jets are used for rinsing to improve cohesion, then adhesion between layers increases, but thickness is reduced
Solution Approach 1:
The patent performs hydroentanglement treatment before the final rinsing operation. This preliminary consolidation creates a structurally robust web that can withstand subsequent rinsing without excessive compression. The pre-established hydrobonds provide a framework that maintains thickness while still allowing for necessary rinsing operations to complete the manufacturing process.
4Shape
If card webs are folded to form sheets for absorbent products, then the desired width and format are achieved, but delamination occurs between layers
Solution Approach 1:
The patent replaces mechanical folding and stacking of card webs with a continuous hydroentangled nonwoven formation process. High-pressure water jets bind fibers into a cohesive sheet structure that maintains integrity without requiring multiple folded layers. This eliminates the delamination problem inherent in folded card web constructions while achieving the desired product format and width.
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 product achieves enhanced mechanical resistance and volume while maintaining softness, with improved cohesion and reduced delamination, allowing for greater tensile strength without chemical binders, and can be manufactured using a process involving hydrobinding, bleaching, and rinsing with controlled vacuum to maintain thickness.
Implementation Method 1
The web is then driven by a belt to different treatment stations in a continuous line. The sheet is first impregnated with a scouring solution applied in the form of a liquid blade poured transversely to its direction of movement.
Implementation Method 2
the two layers being bonded by adhesion to any surface between the fibers of the two layers
Implementation Method 3
a fiber treatment step which consists of subjecting the unbleached fiber to successive cleaning and working operations, to a treatment consisting of removing the fats and waxes, using a soda-based scouring solution to make the cotton hydrophilic
Implementation Method 4
The sheet is introduced after impregnation into a vaporizer heated to a temperature close to 100°C in which it remains, while remaining continuous, for the time necessary for the treatment.
Implementation Method 5
The solution is sucked up through the tablecloth by means of a suction slot placed under the canvas.
Implementation Method 6
The solution is sucked up through the tablecloth by means of a suction slot placed under the canvas.
Implementation Method 7
an improvement described in European patent EP 0 805 888 B1. This improvement concerns a rinsing step using high pressure water jets, which provide mechanical energy to the treated surfaces, allowing the interweaving of the surface fibers and improving the resistance of the treated web
Data Source
Figure 1~2
AI summary
The present invention relates to an absorbent fibrous product containing at least 50% of cotton fibers or other cellulose fibers and less than 0.1% of a chemical or hot-melt binder, including a first layer consisting of hydroentangled non-woven fabric and a second layer consisting of fibers that are more weakly bonded together than the fibers of the first layer, the bonding of the fibers of the second layer resulting from a hydrophilic treatment of the layer of fibers, the two layers being bonded by adhesion of the entire surface between the fibers of the two layers, and the debonding force being at least 0.1 N. The invention also relates to a manufacturing method, which includes the following steps: a) forming at least two separate laps of fibers, one of which is at least partially made of cotton fibers or other cellulose fibers; b) consolidating a first of said laps by bonding using fine water jets; c) stacking the laps; and d) the hydrophilic treatment of the formed complex lap by means of wetting, followed by extracting the liquid, in particular by subjecting the lap to negative pressure.