Bicomponent Nonwoven Webs Resist Breakage During Aperture Formation
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Solution Overview
Problem
Nonwoven webs used in absorbent articles are prone to fiber breakage and neckdown during manufacturing and converting processes due to insufficient extensibility and strain forces, leading to contamination and reduced product quality.
Innovation Solution
Development of highly extensible nonwoven webs with multi-component fibers, specifically bi-component fibers having a low-crystallinity polypropylene core and high-crystallinity polyethylene sheath, which provide improved tensile properties and resistance to fiber breakage, allowing for the creation of apertures and patterned features while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If strain force exceeding 100% is applied to create apertures and value-added features, then the nonwoven web gains improved fluid handling properties and aesthetic appearance, but fiber breakage occurs in non-overbonded areas weakening the web
Solution Approach 1:
The nonwoven web is pre-bonded at specific locations before aperture formation. This preliminary bonding creates predetermined weak points that will rupture during stretching to form apertures, while the rest of the web maintains its strength and integrity during the high-strain aperture formation process.
Solution Approach 2:
The nonwoven web has non-uniform bonding distribution with overbonded areas and non-overbonded areas. The overbonded areas are designed to rupture and form apertures, while the non-overbonded areas maintain strength and prevent fiber breakage during the aperture formation process.
2Ease of manufacture
If high strain force is applied to create patterned apertures, then the nonwoven web achieves improved depth perception and fluid handling, but fiber breakage occurs in lanes without overbonds
Solution Approach 1:
The patterned nonwoven web has spatially varying bonding characteristics with overbonded lanes designed to form apertures and non-overbonded lanes designed to maintain strength. This local quality differentiation allows the web to withstand high strain forces during patterned aperture formation without fiber breakage in the non-overbonded lanes.
3Adaptability or versatility
If elastomeric polymers are used to increase extensibility, then the nonwoven web can accommodate strain forces, but the value-added features recover to their pre-processed state
Solution Approach 1:
The nonwoven web utilizes thermal phase transitions during processing. The polymers are heated above their melting points to enable extensibility and aperture formation, then cooled to stabilize the apertures in their formed state, preventing recovery to the pre-processed configuration.
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 solution enhances the nonwoven webs' ability to withstand strain forces during manufacturing, reducing fiber breakage and neckdown, resulting in stronger, more efficient conversion into absorbent articles with improved fluid handling and aesthetic properties.
Implementation Method 1
bi-component fibers having a low-crystallinity polypropylene core and high-crystallinity polyethylene sheath
Implementation Method 2
highly extensible nonwoven webs
Data Source
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AI summary
A highly extensible nonwoven web is provided. The highly extensible nonwoven web may include continuous multi-component fibers. The continuous multi-component fibers may include polypropylene, wherein the polypropylene has a crystallinity of less than about 41%. The polypropylene may have a melting temperature of less than about 161C. The highly extensible nonwoven web may define a plurality of apertures. The apertures may be patterned. The highly extensible nonwoven web may form a portion of an absorbent article.