Cellulose Nonwoven Network for High Opacity at Low Basis Weight
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Solution Overview
Problem
Existing nonwovens with low basis weight struggle to achieve high opacity without costly additives or complex processes, and those with synthetic polymers lack biodegradability and water absorption.
Innovation Solution
A nonwoven composed of regenerated cellulose molded bodies with monofilament sections of varying diameters ≤15 μm for 90% of their length, interconnected via node points, forming a network without matting agents or binders, produced via a lyocell process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If matting agents such as titanium dioxide or zinc oxide are added to increase opacity, then opacity is improved, but cost increases and strength and flexibility of fibers are significantly reduced
Solution Approach 1:
The patent removes matting agents (titanium dioxide, zinc oxide) from the nonwoven structure entirely. Instead of adding opaque particles, the invention achieves opacity through the inherent properties of regenerated cellulose fibers with specific cross-sectional geometries (hollow, ribbed, or irregular shapes) that scatter light without requiring external additives, thereby eliminating the harmful effects of matting agents on fiber strength and flexibility
Solution Approach 2:
The patent changes the physical parameters of the cellulose fibers themselves rather than adding separate opaque materials. By controlling fiber cross-sectional geometry (creating hollow fibers, ribbed fibers, or fibers with irregular cross-sections) during the spinning process, the invention achieves high opacity through the fibers' own structural characteristics, altering the light-scattering parameter from particle-based to structure-based
2Strength
If synthetic polymer fibers are used to produce spunbonded fabrics, then mechanical strength is improved, but biodegradability is lost and water absorption capacity is reduced
Solution Approach 1:
The patent changes the material composition from synthetic polymers to regenerated cellulose. By utilizing natural cellulose fibers with controlled cross-sectional geometries (hollow, ribbed, irregular), the invention maintains mechanical strength through the structural design of the fibers while achieving biodegradability and enhanced water absorption capacity inherent to cellulose materials
Solution Approach 2:
The patent creates a composite structure within the nonwoven by combining regenerated cellulose fibers with specific cross-sectional geometries (hollow cores, ribbed surfaces, irregular shapes). This internal composite structure provides both mechanical strength through the fiber network and functional properties (biodegradability, water absorption) through the cellulose material, eliminating the need for synthetic polymers
3Strength
If multilayer structure is used to meet strength and stability requirements, then strength is improved, but flexibility is reduced and production complexity increases
Solution Approach 1:
The patent segments the strength-function into individual fiber properties rather than requiring multiple layers. By creating single fibers with complex cross-sectional geometries (hollow, ribbed, irregular shapes) that inherently provide strength and stability, the invention eliminates the need for multilayer construction, thereby reducing production complexity and maintaining flexibility
Solution Approach 2:
The patent applies local quality by giving individual fibers specific cross-sectional geometries tailored to provide strength and stability. Instead of achieving these properties through the collective arrangement of multiple layers, the invention embeds the strength-function directly into the local structure of each fiber, simplifying the overall nonwoven construction to a single layer while maintaining mechanical performance
4Weight of moving object
If basis weight is reduced to meet demand for lightweight products, then weight is improved, but opacity becomes insufficient and tear resistance feels low
Solution Approach 1:
The patent changes the density and cross-sectional geometry parameters of the cellulose fibers to optimize the basis weight-to-opacity ratio. By using hollow fibers, ribbed fibers, or irregularly shaped fibers, the invention achieves high opacity and perceived tear resistance at lower basis weights, as the light-scattering structural features remain effective even with reduced material quantity
Solution Approach 2:
The patent utilizes porous and hollow fiber structures to achieve high opacity at low basis weight. The hollow cross-sections and irregular geometries create internal light-scattering interfaces that provide opacity without requiring proportional increases in material density, allowing lightweight nonwovens to maintain the visual and tactile properties of heavier materials
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 nonwoven achieves high specific opacity (>1.0%·m2/g) with low basis weight, biodegradability, and improved water absorption, while maintaining mechanical strength and flexibility.
Implementation Method 1
the nonwoven, in the dry state, having a specific opacity greater than or equal to 1.0%·m2/g
Implementation Method 2
improved water absorption
Data Source
AI summary
The invention relates to a nonwoven as well as to a wipe, a face mask, and a dryer sheet including the nonwoven, which includes a network of molded bodies, the nonwoven, in the dry state, having a specific opacity of greater than or equal to 1.0%·m2/g. In order to create a nonwoven of low basis weight, which is easy to produce and has, without special modifications, a high specific opacity, it is proposed that the molded bodies are regenerated cellulosic molded bodies and are materially interconnected via node points to form the network, and the regenerated cellulosic molded bodies comprising monofilament sections extending between node points, whose diameter varies along their lengthwise extension and which have a diameter of less than or equal to 15 μm for at least 90% of their lengthwise extension.