Layered Nonwoven Pore Gradient for Fast Fluid Transfer
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Solution Overview
Problem
Existing nonwovens used in absorbent articles face challenges in achieving a pore size gradient without compromising surface smoothness, leading to inadequate fluid transfer and discomfort for the wearer.
Innovation Solution
A nonwoven design with a first layer having larger mean pore size and fiber fineness equal to or smaller than the second layer, combined with specific polymer compositions like PTT and PBT, creates a capillary gradient for efficient fluid transfer while maintaining a smooth surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high denier fibers are used on the upper side to create pore size gradient, then fluid drainage capability is improved, but surface smoothness and gentleness deteriorate
Solution Approach 1:
The nonwoven fabric is designed with spatially varying fiber properties: the upper surface layer uses low denier fibers (0.5-2.0 dtex) to maintain smoothness and comfort against the skin, while the lower layers progressively increase in fiber denier (up to 5.0 dtex or more) to enhance capillary suction power for fluid drainage. This local differentiation of fiber characteristics resolves the contradiction between surface comfort and fluid management performance.
Solution Approach 2:
Instead of varying pore size in a single dimension by using uniform high denier fibers throughout, the invention creates a three-dimensional gradient structure where fiber denier increases progressively from the upper surface toward the lower layers. This dimensional approach to pore size variation allows the upper surface to maintain low denier fibers for smoothness while achieving effective fluid drainage through the deeper layers with higher denier fibers.
2Speed
If pore size gradient is created to improve fluid transfer, then fluid absorption speed is improved, but surface smoothness may be compromised
Solution Approach 1:
The nonwoven fabric implements local quality differentiation by using fine denier fibers (0.5-2.0 dtex) in the upper surface layer to ensure smoothness and comfort, while progressively increasing fiber denier in lower layers to create the pore size gradient necessary for rapid fluid absorption. This localized fiber selection allows both surface comfort and fast fluid transfer to coexist.
Solution Approach 2:
The nonwoven fabric functions as a composite structure with multiple fiber types of different deniers combined in a gradient arrangement. The composite nature allows the fine fibers at the surface to provide smoothness while coarser fibers in the bulk provide rapid capillary wicking, achieving both surface quality and fluid absorption speed simultaneously.
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 rapid fluid transfer and improved dryness and cleanness by utilizing a pore size gradient without compromising surface smoothness, enhancing the comfort and performance of absorbent articles.
Implementation Method 1
absorbent articles having a capillary gradient is desirable as it can provide better fluid drainage from a wearer-facing surface of the topsheet to an adjacent layer
Data Source
AI summary
The present disclosure relates to a nonwoven including a first layer and a second layer. The first layer has first fibers and a first mean pore size. The first fibers have a first fiber fineness. The second layer includes second fibers and a second mean pore size. The second fibers have a second fiber fineness, and the second fiber fineness is equal to or greater than the first fiber fineness, and the second mean pore size is smaller than the first mean pore size. The first fibers may include a polymer and the polymer may include polytrimethylene terephthalate, polybutylene terephthalate and a combination thereof. The second fiber may include a thermoplastic fiber. The nonwoven may be included in an absorbent article. At least one of the topsheet and the fluid management layer of the absorbent article may include the nonwoven.