Stratified Coform Nonwoven Web Softness Strength Balance
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Solution Overview
Problem
Conventional coform webs face challenges in achieving a balance between softness and strength, particularly when using polyethylene homopolymers which increase softness but reduce strength.
Innovation Solution
A stratified coform nonwoven web material is developed, comprising outer regions with bicomponent meltblown polymer fibers and absorbent fibers, and a central region with monocomponent meltblown polymer fibers and absorbent fibers, optimizing the distribution of polymer components to enhance both softness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If polyethylene homopolymers are used to increase softness, then softness is improved, but strength is reduced
Solution Approach 1:
The patent applies local quality by using bicomponent fibers with different polymer components distributed in specific regions. The first polymer component (e.g., polypropylene) provides strength in the central region, while the second polymer component (e.g., polyethylene) provides softness in the outer regions. This spatial distribution of different material properties resolves the contradiction between strength and softness.
Solution Approach 2:
The patent uses composite materials by combining two different polymer components in bicomponent fibers. Each polymer component contributes different properties: one provides strength while the other provides softness. The composite fiber structure allows both properties to coexist within the same fiber, resolving the strength-softness contradiction.
2Shape
If polyethylene content is increased to improve softness, then softness is improved, but structural integrity deteriorates
Solution Approach 1:
The patent implements local quality by concentrating the second polymer component (providing softness) in the outer regions while maintaining the first polymer component (providing structural integrity) in the central region. This regional differentiation allows high softness at the surface while preserving overall structural integrity.
Solution Approach 2:
The patent segments the fiber structure into bicomponent fibers with distinct regions containing different polymer components. The segmentation allows the soft polymer to be localized in outer regions while the strong polymer maintains the central structure, preventing structural deterioration despite high softness content.
3Strength
If conventional coform web composition is used to maintain strength, then strength is preserved, but softness is reduced
Solution Approach 1:
The patent reverses the conventional approach by using local quality to concentrate strength-providing polymer in the central region and softness-providing polymer in the outer regions. This inverted distribution achieves both high strength and high softness, overcoming the limitation of conventional uniform composition.
Solution Approach 2:
The patent uses composite bicomponent fibers where two polymer materials work synergistically: one polymer provides the strength backbone while the other provides the soft surface feel. This composite approach allows simultaneous achievement of both strength and softness, unlike conventional single-polymer coform webs.
Data Source
AI summary
Soft and strong nonwoven web materials and methods of formation are described. In one embodiment, a nonwoven web may comprise a first and second outer regions of meltblown polymer fibers and absorbent fibers, the meltblown fibers formed of first and second polymer components where the second polymer component comprises greater than 0% and less than or equal to 20% by weight of a total polymeric material content of the meltblown polymer fibers, and a central region disposed between the first and second outer regions and comprising meltblown polymer fibers and absorbent fibers, the meltblown fibers being different than the meltblown polymer fibers of the first and second outer regions and not comprising the second polymer component.