Airlaid composite sheet material and method
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Solution Overview
Problem
Conventional absorbent articles face issues with rapid fluid acquisition in the z-direction but inadequate lateral fluid distribution, leading to localized fluid exposure and discomfort for the wearer.
Innovation Solution
A composite sheet material comprising a fluid acquisition layer and an airlaid layer with a blend of cellulose and non-cellulose staple fibers, thermally bonded without adhesives, providing a density gradient for efficient fluid transport and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional materials are used in AQDL, then rapid fluid acquisition in z-direction is achieved, but lateral fluid distribution in x and y directions is inadequate
Solution Approach 1:
The patent employs a composite AQDL structure combining a nonwoven fabric layer with an airlaid layer containing cellulose and non-cellulose fibers. This composite structure enables the nonwoven layer to provide rapid vertical fluid acquisition while the airlaid layer with its specific fiber blend delivers improved lateral fluid distribution, thus resolving the contradiction between speed and distribution precision
Solution Approach 2:
The patent applies different material compositions to different functional zones: the nonwoven fabric layer is optimized for vertical fluid transport speed, while the airlaid layer is specifically designed with cellulose and non-cellulose fiber blend to enhance lateral distribution. Each layer performs its specialized function, resolving the contradiction through localized functional optimization
2Loss of time
If rapid fluid transport is implemented, then fluid is quickly moved from top sheet to absorbent core, but fluid pooling near skin occurs due to insufficient distribution
Solution Approach 1:
The patent converts the potential harm of rapid fluid transport (which causes pooling) into a benefit by introducing the airlaid layer with specific fiber composition. This layer captures the rapidly transported fluid and redistributes it laterally, transforming the harmful concentration effect into a beneficial distribution effect that prevents skin exposure while maintaining quick transport
3Strength
If adhesive bonding is used to bond layers, then strong bonding is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the chemical bonding mechanism (adhesives) with a thermal bonding mechanism. The airlaid layer containing thermoplastic fibers is thermally bonded to the nonwoven fabric layer through heat application, eliminating the need for adhesive applications, drying processes, and associated equipment, thus reducing manufacturing complexity while maintaining bonding strength
Solution Approach 2:
The patent changes the bonding parameter from chemical (adhesive-based) to thermal (heat-based). By incorporating thermoplastic fibers in the airlaid layer, the bonding process utilizes temperature as the controlling parameter instead of adhesive chemistry, simplifying the overall manufacturing process while achieving adequate bonding strength
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 composite sheet material enhances fluid distribution and absorption, offering improved comfort, reduced reverse osmosis, and a dry-touch surface, while maintaining softness and fluffiness, thus addressing the limitations of prior art materials.
Implementation Method 1
The non-cellulose staple fibers may be thermally bonded to the cellulose staple fibers and to each other
Implementation Method 2
This rapid transport (also referred to herein as flash permeation) transports the fluid in the z-direction from the top sheet to the absorbent core
Implementation Method 3
the airlaid component comprises at least one airlaid nonwoven layer comprising a homogenous mixture of cellulose and non-cellulose staple fibers that are deposited directly onto the surface of the fluid acquisition layer
Data Source
AI summary
Provided is a composite sheet that is particularly useful as an AQDL component in absorbent articles. The composite sheet includes a fluid acquisition component and an airlaid component. The airlaid component may include one or more airlaid layers that are successively formed overlying each other. Each of the airlaid layers are adjacent to, and in direct contact with, immediately adjacent layers of the airlaid component so that adjacent layers are in fluid communication with respect to each other. The fluid acquisition component includes a nonwoven fabric comprising a carded nonwoven fabric comprised of a plurality of staple fibers that are air through bonded to each other to form a coherent nonwoven fabric. The airlaid layer(s) include a blend of cellulose and non-cellulose staple fibers. The staple fibers may be bicomponent fibers having a polyethyelene sheath and a polypropylene or polyethylene terephthalate core, and mixtures of such fibers.