Water-absorbent Sheet Structure with Adhesive Matrix
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Solution Overview
Problem
Conventional absorbent articles face challenges with the 'gel-blocking phenomenon' when using high amounts of water-absorbent resins, leading to reduced liquid diffusibility and shape retention issues, and existing solutions fail to balance adhesion and liquid absorbency effectively, resulting in either gel blocking or liquid leakage.
Innovation Solution
A water-absorbent sheet structure with a water-absorbent resin and adhesive sandwiched between nonwoven fabrics, where the resin is evenly dispersed and has a specified water-retention capacity and peeling strength, preventing gel blocking and ensuring fast liquid permeation and shape retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of water-absorbent resin is used to achieve thinning and high absorption capacity, then the water-absorbent capacity is improved, but the gel-blocking phenomenon occurs which reduces liquid diffusibility
Solution Approach 1:
The patent applies local quality by creating regions with different resin concentrations and properties. The absorbent layer contains water-absorbent resin particles distributed within a matrix, creating local variations in absorption capacity and gel formation characteristics that prevent uniform gel-blocking while maintaining high overall absorption
Solution Approach 2:
The patent uses composite materials by combining water-absorbent resin particles with a matrix material in the absorbent layer. This composite structure allows the resin to provide high absorption capacity while the matrix prevents excessive gel formation and maintains liquid diffusibility throughout the layer
2Length of stationary object
If hydrophilic fibers are reduced to thin the absorbent material, then the thickness is reduced, but the shape-retaining ability deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical parameters of the absorbent layer materials. The water-absorbent resin and matrix materials are selected and configured to provide appropriate mechanical properties and shape retention without relying on traditional hydrophilic fibers, enabling thinning while maintaining structural integrity
3Strength
If adhesive strength is increased to prevent resin migration, then the shape retention is improved, but the liquid absorbency is reduced due to gel-blocking
Solution Approach 1:
The patent applies local quality by creating regions with different adhesive properties. The adhesive is strategically placed and formulated to provide strong binding in areas where resin migration is a concern, while maintaining porosity and absorption capacity in areas where liquid contact occurs, thus preventing gel-blocking
Solution Approach 2:
The patent uses porous materials in the adhesive and matrix structure to maintain liquid permeability. The porous architecture allows liquid to penetrate through the adhesive-bonded regions without being blocked by excessive gel formation, balancing adhesion strength with absorption capability
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 achieves excellent shape retention and liquid absorbency, preventing gel blocking and leakage, allowing for thin and efficient absorbent materials suitable for sanitary napkins and other applications.
Implementation Method 1
a water-absorbent resin (a superabsorbent polymer) having a water-retention capacity
Implementation Method 2
water-absorbent resin particles which have a mass-average particle size of 50 μm or more and a water-absorption rate of 50 seconds or less
Implementation Method 3
an absorbent layer containing a water-absorbent resin and an adhesive
Data Source
Figure 1
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AI summary
A water-absorbent sheet structure comprises a structure in which an absorbent layer comprising a water-absorbent resin and an adhesive is sandwiched with nonwoven fabrics from an upper side and a lower side of the absorbent layer, wherein the water-absorbent resin is contained in an amount of 10 g/m2 or more and less than 100 g/m2, and wherein the water-absorbent resin has a water-retention capacity of saline solution of from 35 to 80 g/g, and wherein the water-absorbent sheet structure has a peeling strength of from 0.05 to 3.0 N/7 cm. The water-absorbent sheet structure according to the present invention exhibits some effects that a water-absorbent sheet structure has excellent shape retaining ability even when the structure is thin, so that the water-absorbent sheet structure does not undergo deformation of the form before liquid absorption or after the absorption, and is capable of sufficiently exhibiting absorbent properties not only to a low-viscosity liquid such as urine but also a high-viscosity liquid such as menses.