Multi-layer Absorbent Core with Graded SAP for Gel Blocking
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Solution Overview
Problem
Existing absorbent cores in disposable absorbent articles face challenges such as gel blocking, which leads to premature leakage, and high costs associated with superabsorbent materials. Additionally, there is a need for more environmentally friendly alternatives that maintain excellent absorption and rewet performance.
Innovation Solution
The absorbent core comprises a multi-layer structure with a top layer containing high Absorbency Under Load (AUL) superabsorbent polymer grades and a bottom layer with fast-absorbing superabsorbent polymer grades. This configuration, combined with a mixture of cellulose fibers and superabsorbent polymers, enhances liquid distribution and reduces gel blocking. The core wrap substrate is designed to minimize additional layers, promoting optimal fluid distribution and cost-efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If superabsorbent materials are used to increase liquid absorption capacity, then absorption capacity is improved, but gel blocking occurs causing premature leakage
Solution Approach 1:
The absorbent core is divided into multiple layers with different superabsorbent polymer grades. The top layer contains high AUL SAP grades that resist gel blocking, while the bottom layer contains fast-absorbing SAP grades. This segmentation allows each layer to perform its specific function optimally, preventing premature leakage while maintaining high absorption capacity.
Solution Approach 2:
Different regions of the absorbent core are assigned different SAP grades based on their functional requirements. The top layer (closer to skin) uses high AUL SAP for resistance to gel blocking under load, while the bottom layer uses fast-absorbing SAP for rapid liquid uptake. This local differentiation of material properties resolves the contradiction between absorption capacity and leakage prevention.
2Quantity of substance
If more superabsorbent material is used to improve absorption performance, then absorption performance is improved, but cost increases
Solution Approach 1:
The invention changes the parameter of SAP grade distribution within the core rather than uniformly increasing SAP content. By optimizing the ratio and placement of different SAP grades (high AUL in top layer, fast-absorbing in bottom layer), the core achieves superior absorption performance without proportionally increasing material cost, as each SAP grade is used where it provides maximum value.
Solution Approach 2:
The absorbent core uses a composite structure combining different SAP grades with cellulose fibers in specific layers. This composite approach allows the core to leverage the strengths of each material - high AUL SAP for load-bearing resistance, fast-absorbing SAP for rapid uptake, and cellulose for capillary action - achieving high performance without requiring excessive amounts of expensive SAP material throughout the entire core.
3Ease of manufacture
If traditional single-layer core structure is used, then manufacturing is simple, but liquid distribution is poor and gel blocking occurs
Solution Approach 1:
The core is segmented into multiple layers with distinct SAP grade compositions. This layered segmentation improves liquid distribution efficiency by creating zones with different absorption characteristics, preventing gel blocking, and facilitating progressive liquid movement from top to bottom layers, while still maintaining manufacturability through standard multi-layer forming processes.
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 multi-layer absorbent core effectively improves liquid handling and cost-efficiency while providing a more environmentally friendly option. It achieves excellent absorption and rewet performance by minimizing gel blocking and ensuring uniform liquid distribution across the core.
Implementation Method 1
superabsorbent materials in the form of granules, beads, fibers, bits of film, globules, etc., have been favored for such purposes. Such superabsorbent materials generally (also referred to as superabsorbent polymer particles or SAP) are polymeric gelling materials that are capable of absorbing and retaining large quantities of liquid
Implementation Method 2
Whenever a particle of the superabsorbent material and absorbent core is wetted, it swells and forms a gel
Implementation Method 3
Adequate absorbency of liquid by the absorbent core at the point of initial liquid contact and rapid distribution of liquid away from this point is necessary
Data Source
Figure 1A~1C
Figure 2
Figure 3A~3C
AI summary
An absorbent article comprising: a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core positioned between said topsheet and backsheet, wherein the absorbent core comprises an absorbent material, said absorbent material comprising a mixture, or blend, of cellulose fibers and superabsorbent polymers, wherein the absorbent core comprises at least a top layer (L1) and a bottom layer (L2) wherein the bottom layer (L2) is positioned between the top layer (L1) and the backsheet, and wherein said absorbent material is contained within at least one core wrap substrate enclosing said absorbent material therein, wherein the at least top layer (L1) and a bottom layer (L2) are directly stacked one on top of the other to form a contact zone (Zc) where the top layer (L1) directly adjoins to the bottom layer (L2), and wherein the top layer (L1) comprises one or more first superabsorbent polymer grades (SAP1) and the bottom layer (L2) comprises one or more second superabsorbent polymer grades (SAP2), wherein the first superabsorbent polymer grades (SAP1) have an AUL that is greater than the AUL of second superabsorbent polymer grades (SAP2), and wherein the first superabsorbent polymer grades (SAP1) have an AUL, as measured according to the test method herein, of greater than 15 g/g.