Channeled Absorbent Core Bonding via Localized Pressure
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Solution Overview
Problem
There is a need to improve the adhesion between top and bottom layers of the core wrap in absorbent cores with channels, to enhance production efficiency and reduce wear and tear on apparatus components, especially at high production speeds.
Innovation Solution
The method involves using a first endless moving surface with molds having non-porous inserts, where the molds are in fluid communication with an under-pressure source except for the insert. A nonwoven web is fed over the molds, absorbent material is deposited, and then removed from areas corresponding to the insert. The absorbent material is sandwiched between upper and lower layers of nonwoven web, and the layers are joined together in areas corresponding to the insert, forming an absorbent core with channels substantially free of absorbent material. Selective pressures are applied to the central and peripheral regions of the core to join the core wrap layers effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If uniform pressure is applied across the entire absorbent core during manufacturing, then the bonding between core wrap layers is strengthened, but the superabsorbent polymer particles may be crushed and the channel structure may be damaged
Solution Approach 1:
The patent applies different pressure levels to different regions of the absorbent core during manufacturing. Specifically, higher pressure is applied to the peripheral regions where core wrap layer bonding is needed, while lower or no pressure is applied to the central region containing the channel and superabsorbent polymer particles. This localized pressure application strengthens bonding at the edges without crushing the sensitive components in the channel area.
Solution Approach 2:
The pressing operation is divided into multiple zones with different pressure characteristics. The pressing element is segmented into regions that apply different forces - peripheral zones for bonding and central zones for protection. This segmentation allows simultaneous achievement of strong layer adhesion and preservation of the channel structure with intact superabsorbent polymer particles.
2Productivity
If high production speeds are used, then productivity is improved, but the wear and tear on apparatus components increases
Solution Approach 1:
The patent optimizes the pressure distribution parameters during the bonding process to reduce mechanical stress on apparatus components. By using localized pressure application rather than uniform high pressure across the entire core, the wear on pressing elements and other components is reduced, allowing sustained high-speed operation without excessive component degradation.
3Strength
If high pressure is applied to bond core wrap layers, then adhesion is improved, but the channel structure may be compromised
Solution Approach 1:
The patent implements localized pressure application where high pressure is concentrated on the peripheral regions of the absorbent core to ensure strong adhesion between core wrap layers, while the central region containing the channel is either excluded from pressing or subjected to minimal pressure. This preserves the channel's geometric integrity and ensures it remains free of absorbent material as required.
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 method achieves strong bonding between the top and bottom core wrap layers in the channel region, while minimizing the risk of damaging the core wrap layers or crushing superabsorbent polymer particles, thus allowing for faster production speeds and reduced wear and tear on apparatus components.
Implementation Method 1
the molds are in fluid communication with an under-pressure source except for the insert
Implementation Method 2
selective pressures are applied to the central and peripheral regions of the core to join the core wrap layers effectively
Data Source
AI summary
A method for making an absorbent article comprising an absorbent core comprising one or more channels, the method comprising the steps of: i. providing a first endless moving surface comprising a plurality of molds, each mold comprising a non-porous insert therein, typically said insert having the inverse shape of said channel(s), wherein the molds are in fluid communication with an under-pressure source except for said insert; ii. feeding a first nonwoven web to said first endless moving surface and over one or more said molds; iii. depositing an absorbent material, comprising cellulose fibers and/or superabsorbent polymer particles, over at least a portion of said nonwoven web; iv. removing said absorbent material from areas of the nonwoven web corresponding to said insert; v. applying a second nonwoven web directly or indirectly over the absorbent material, or folding said first nonwoven web, such to sandwich said absorbent material between upper and lower layers of said nonwoven web(s); vi. joining said upper and lower layers together at least in the areas of the nonwoven web(s) corresponding to the insert to form an absorbent core having one or more channels substantially free of absorbent material; vii. optionally joining an acquisition distribution layer to said absorbent core, typically a skin facing surface of said upper layer; viii. optionally laminating said absorbent core and acquisition distribution layer between a liquid pervious topsheet and a liquid impervious backsheet; wherein step vi. comprises the step of selectively applying a first pressure onto the absorbent core, preferably only, in a central portion thereof and a second pressure, preferably only, along peripheral longitudinal side edges thereof running opposite and parallel to each other and being outboard of said central portion, said central portion corresponding at least to a region of the core comprising said channel(s), and wherein said first and second pressures are successively applied along a machine direction (MD).