Hydroentangled Nonwoven Material Uniformity via Layer Inversion
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Solution Overview
Problem
Hydroentangled nonwoven materials often exhibit marked twosidedness due to poor mixing of layers during the entangling process, resulting in differing properties on each side, particularly when pulp and synthetic fibers are combined, which is pronounced with spunlaid filaments forming flat layers that mix poorly.
Innovation Solution
An in-line process involving wetlaying a first fibrous web of wood pulp fibers and manmade staple fibers, hydroentangling, laying spunlaid filaments on top, wetlaying a second fibrous web, and hydroentangling together in multiple stations to form a combined web with reversed layers, ensuring both sides have similar appearances and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple fibrous layers are combined during hydroentangling, then the material's absorption capacity and strength are improved, but the layers do not mix thoroughly resulting in marked twosidedness
Solution Approach 1:
The patent applies inversion by reversing the layer sequence halfway through the hydroentangling process. The forming fabric is inverted 180 degrees, causing the layers that were originally positioned in a specific sequence to be reversed in the final product. This ensures that both sides of the nonwoven material have similar appearances and properties, eliminating the marked twosidedness that would otherwise result from poor layer mixing during entangling.
2Shape
If spunlaid filaments are laid on top of hydroentangled web, then the material structure is formed, but the filaments form flat layers that mix poorly with other fibers
Solution Approach 1:
The patent places spunlaid filaments on top of the hydroentangled web and then inverts the forming fabric halfway through processing. This inversion causes the spunlaid filaments to be repositioned and thoroughly mixed with the underlying fibrous layers during the continued hydroentangling process, preventing them from forming separate flat layers and achieving homogeneous fiber distribution throughout the material.
Solution Approach 2:
The spunlaid filaments are laid on the hydroentangled web before the inversion and continued hydroentangling occurs. This preliminary placement ensures that the filaments are already in position to be mixed with the other fibers during the subsequent processing steps, rather than being added afterward when mixing would be difficult.
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 reduces twosidedness by thoroughly integrating the layers, resulting in hydroentangled nonwoven materials with uniform properties on both sides, improving the material's homogeneity and performance.
Implementation Method 1
the fibres are entangled by means of very fine water jets under high pressure
Implementation Method 2
Several rows of water jets are directed against the fibre web
Data Source
Figure 1
Figure 2
AI summary
A method of producing a nonwoven material by hydroentangling a fiber mixture containing spunlaid filaments, natural fibers and synthetic staple fibers, wherein a first fibrous web (12) of natural fibers and at least 10% by fiber weight manmade staple fibers is wetlaid and hydroentangled in a first hydroentangling station (13), spunlaid filaments (16) are laid on top of the hydroentangled first fibrous web (12) and a second fibrous web (19) comprising natural fibers is wetlaid on top of said spunlaid filaments (16). The second fibrous web (19) is hydroentangled together with the spunlaid filaments (16) in a second hydroentangling station (20) and the combined webs are reversed and the first fibrous web (12) of natural fibers and manmade staple fiber is hydroentagled together with the spunlaid filaments (16) in a third hydroentangling station (25).