Absorbent Core Channels for Fiber Deposition Control
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Solution Overview
Problem
In the production of air-formed fibrous absorbent cores, such as those used in disposable diapers and incontinence articles, there is a challenge in ensuring adequate deposition of fibrous and superabsorbent material in the liquid holding formation, leading to inconsistent basis weight, fiber damage, and reduced strength due to increased airflow resistance and inefficient entanglement.
Innovation Solution
The introduction of a forming surface with longitudinally extending channels in the liquid holding formation, which increases the surface area and inhibits liquid flow past the peripheral edge, allowing for more effective deposition of fibrous material and maintaining a higher basis weight, thereby enhancing the absorbency and strength of the core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vacuum suction is used to draw the air-entrained fiber stream onto the forming surface, then high-speed commercial operation is achieved, but inadequate deposition of fiber in the liquid holding formation area occurs due to increased flow resistance
Solution Approach 1:
The forming surface is segmented into multiple zones with different vacuum pressures. The liquid holding formation area is assigned a lower vacuum pressure zone to reduce airflow resistance and improve fiber deposition, while other areas maintain higher vacuum pressures for normal production speed. This segmentation allows simultaneous achievement of high-speed operation and adequate fiber deposition in the critical liquid holding formation area.
2Shape
If the liquid holding formation area is made narrow to achieve desired shape, then product form is improved, but fiber deposition becomes even more inadequate due to heightened flow resistance
Solution Approach 1:
The forming surface is designed with locally differentiated vacuum pressure characteristics. The narrow liquid holding formation area is positioned over a region with reduced vacuum pressure to compensate for the heightened flow resistance caused by its narrow geometry. This local quality adjustment ensures adequate fiber deposition in the narrow area while maintaining the desired product shape.
3Manufacturing precision
If vacuum pressure is increased to improve fiber deposition, then basis weight consistency is improved, but fiber damage increases due to excessive retention in the fiberizer
Solution Approach 1:
Instead of applying high vacuum pressure uniformly across the entire forming surface, the system segments the vacuum pressure distribution spatially. The liquid holding formation area receives targeted lower vacuum pressure to reduce fiber damage, while other areas operate at higher pressures to maintain basis weight consistency. This segmented approach decouples the conflicting requirements of basis weight control and fiber protection.
4Quantity of substance
If the forming layer basis weight increases to improve liquid holding capacity, then absorbency is improved, but resistance to air flow increases causing inadequate fiber deposition
Solution Approach 1:
The vacuum pressure distribution is made dynamic and adaptive rather than static. The system adjusts vacuum pressure levels in real-time based on the forming layer basis weight and airflow resistance conditions. As the forming layer thickens and resistance increases, the vacuum pressure in the liquid holding formation area is automatically reduced to maintain adequate airflow and fiber deposition, enabling continuous production of high-capacity absorbent cores without flow resistance penalties.
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
This solution ensures a consistent and higher basis weight in the liquid holding formation, reducing fiber damage and improving the absorbency and structural integrity of the absorbent core, while maintaining the strength of the surrounding regions.
Implementation Method 1
The fibers and superabsorbent particles have then been entrained in an air stream and directed to a foraminous forming surface
Implementation Method 2
can typically employ a pneumatic flow mechanism, such as vacuum suction apparatus, to produce a pressure differential across the forming surface. The pressure difference causes an airflow through the openings or perforations in the plate or screen of the forming surface
Implementation Method 3
fibrous material is deposited on the forming surface as it passes through a chamber of the fluent fibers, forming a layer of fibrous material on the forming surface
Data Source
AI summary
An absorbent core comprises an elongate liquid holding formation with a peripheral edge. The liquid holding formation has a surface formed with at least one channel extending longitudinally in the core for distributing liquid lengthwise along the core. The channel has longitudinally opposite ends spaced longitudinally inward from the peripheral edge of the liquid holding formation to inhibit the flow of liquid in the channels past the peripheral edge of the liquid holding formation.