Fractionated Water Absorbent Sheet Preventing Gel Blocking
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Solution Overview
Problem
Existing absorbent articles face challenges in achieving thinness while avoiding gel-blocking phenomena, maintaining high liquid permeation rates, and minimizing re-wet and leakage, especially when using a large amount of water-absorbent resin with minimal hydrophilic fibers.
Innovation Solution
A water-absorbent sheet structure is developed, comprising a primary and secondary absorbent layer with a breathable substrate layer, where the absorbent layers are fractionated and sandwiched between hydrophilic nonwoven fabrics, using a specific range of water-absorbent resin and adhesive amounts to prevent gel-blocking and enhance permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a large amount of water-absorbent resin is used with reduced hydrophilic fibers to achieve thinning, then the thickness and weight of the absorbent article are reduced, but gel-blocking phenomenon occurs and liquid permeation rate is slowed down
Solution Approach 1:
The absorbent core is divided into multiple layers with different functions: a first absorbent layer containing water-absorbent resin particles, a intermediate layer with hydrophilic fibers to prevent gel-blocking, and a second absorbent layer. This segmentation allows each layer to perform its specific function optimally while maintaining overall thinness.
Solution Approach 2:
Different regions of the absorbent core are assigned different material compositions and properties. The intermediate layer specifically uses hydrophilic fibers with high capillary action to create liquid pathways, while the absorbent layers use water-absorbent resin for bulk absorption. This local differentiation resolves the contradiction between thinness and permeation rate.
2Quantity of substance
If a large amount of water-absorbent resin is used to increase absorption capacity, then the liquid retention capacity is improved, but gel-blocking phenomenon occurs and liquid diffusibility is lowered
Solution Approach 1:
The intermediate layer acts as a mediator between the water-absorbent resin layers. It contains hydrophilic fibers that wick liquid through capillary action, preventing the resin particles from directly contacting and blocking each other. This intermediary layer enables the large amount of resin to function without causing gel-blocking.
Solution Approach 2:
The intermediate layer is designed with high porosity and specific pore structure to facilitate liquid flow. The porous structure of the hydrophilic fiber network creates continuous pathways for liquid diffusion, preventing the formation of dense gel blocks while allowing high absorption capacity in the resin layers.
3Length of moving object
If hydrophilic fibers are reduced to achieve thinning, then the thickness is reduced, but the strength and shape retention of the absorbent material are lowered
Solution Approach 1:
The absorbent core is segmented into functional layers where the intermediate layer specifically provides structural support and shape retention using hydrophilic fibers, while the outer absorbent layers provide absorption function. This segmentation allows thinness in the overall structure while maintaining strength in critical regions.
Solution Approach 2:
The absorbent core uses a composite structure combining water-absorbent resin particles with hydrophilic fiber networks. The hydrophilic fibers form a skeletal framework that maintains shape and strength, while the resin particles fill the spaces for absorption. This composite approach enables thinness without sacrificing mechanical properties.
4Object-generated harmful factors
If the ratio of hydrophilic fibers to water-absorbent resin is limited to avoid gel-blocking, then gel-blocking is reduced, but the thinning of the absorbent article is limited
Solution Approach 1:
The absorbent core is divided into distinct layers with the intermediate layer containing primarily hydrophilic fibers and the outer layers containing water-absorbent resin. This segmentation allows the hydrophilic fibers to be concentrated in specific regions where they are most effective at preventing gel-blocking, while maximizing resin content in absorption zones, thereby achieving thinness without gel-blocking.
Solution Approach 2:
Different layers have different fiber-to-resin ratios optimized for their specific functions. The intermediate layer has a high hydrophilic fiber content for liquid wicking and gel-blocking prevention, while the absorbent layers have high resin content for maximum absorption. This local optimization allows the overall article to be thin while preventing gel-blocking where it matters most.
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 solution enables thin, high-performance absorbent sheets with reduced gel-blocking, fast liquid permeation, minimal re-wet, and low leakage, even with a small amount of pulp, while maintaining strength and environmental sustainability.
Implementation Method 1
hydrophilic fibers that play a role of fixing the water-absorbent resin
Implementation Method 2
water-absorbent resin is subjected to be mobile before use or during use because hydrophilic fibers that play a role of fixing the water-absorbent resin are reduced
Implementation Method 3
an absorbent layer containing a water-absorbent resin and an adhesive is sandwiched with a flexible liquid-permeable surface sheet
Data Source
Figure 1~2
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AI summary
A water-absorbent sheet comprising a structure in which an absorbent layer containing a water-absorbent resin and an adhesive is sandwiched with a hydrophilic nonwoven fabric, wherein the water-absorbent sheet has a structure in which the absorbent layer is fractionated into a primary absorbent layer and a secondary absorbent layer with a substrate layer formed by laminating two or more layers of a substrate having breathability adhered together with an adhesive, wherein the substrate layer satisfies the following requirements (1) and (2): (1) the substrate layer having a basis weight of 25 g/m2 or more; and (2) the substrates having breathability being adhered therebetween with an adhesive in an amount of from 0.1 to 50 g/m2. The water-absorbent sheet of the present invention exhibits some excellent effects that the water-absorbent sheet is capable of accomplishing thinning and avoidance of gel blocking phenomenon and liquid leakage, while obtaining basic properties as a water-absorbent sheet at a high level, even for a water-absorbent sheet containing a very small amount of pulps.