Water-absorbent Sheet Structure Preventing Gel-blocking
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Solution Overview
Problem
Conventional absorbent articles, such as disposable diapers, face challenges with the 'gel-blocking phenomenon' due to high amounts of water-absorbent resins, leading to reduced liquid diffusibility and leakage issues, while attempts to reduce hydrophilic fibers for thinning result in compromised shape-retaining ability and liquid absorbency.
Innovation Solution
A water-absorbent sheet structure comprising two types of water-absorbent resins (A and B) with specific water-retention capacities and mass ratios, sandwiched between fibrous webs, to prevent gel-blocking and maintain shape retention, even with a small amount of pulp, enhancing liquid permeability and re-wet reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of water-absorbent resin is used to achieve thinning and reduce bulky materials, then water-absorbent capacity is improved, but gel-blocking phenomenon occurs and liquid diffusibility is markedly lowered
Solution Approach 1:
The patent applies local quality by creating a bicomponent absorbent material where hydrophilic polymer granules and superabsorbent polymer particles are distributed throughout the matrix. The hydrophilic polymers provide liquid pathways in specific regions while superabsorbent particles provide absorption capacity, creating local functional zones that prevent gel-blocking while maintaining high water-absorbent capacity.
Solution Approach 2:
The patent uses composite materials by combining two different polymer systems - hydrophilic polymers (such as polyvinyl alcohol, carboxymethyl cellulose) and superabsorbent polymers (such as crosslinked polyacrylic acid). This composite structure allows the material to exhibit both rapid liquid wicking properties from the hydrophilic component and high absorption capacity from the superabsorbent component, resolving the gel-blocking issue while maintaining thin profile.
2Length of stationary object
If hydrophilic fibers are reduced to thin the absorbent article, then thickness is reduced, but shape-retaining ability and liquid absorbency are compromised
Solution Approach 1:
The patent changes the parameter of fiber composition by replacing traditional hydrophilic cellulose fibers with synthetic hydrophilic polymers and superabsorbent particles. This parameter change allows achieving thinness while maintaining shape retention through the unique properties of these materials - the synthetic polymers provide structural integrity and shape memory effects that cellulose fibers traditionally provided.
3Length of stationary object
If hydrophilic fibers are reduced to thin the absorbent article, then thickness is reduced, but liquid diffusibility is lowered
Solution Approach 1:
The patent employs porous materials by creating a nonwoven matrix structure with interconnected voids and channels. The hydrophilic polymer granules and superabsorbent particles are distributed within this porous matrix, creating multiple liquid pathways that enhance liquid diffusibility while maintaining thin profile. The porous structure allows rapid liquid transport without requiring bulky hydrophilic fiber networks.
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 provides a thin, hygienic absorbent material with excellent shape retention and liquid absorbency, preventing gel-blocking and leakage, while allowing for efficient liquid diffusion and re-wet minimization.
Implementation Method 1
an absorbent layer containing a water-absorbent resin (A) and a water-absorbent resin (B)... sandwiched with fibrous webs... enhancing liquid permeability
Implementation Method 2
water-absorbent resin (A) having a water-retention capacity of saline solution (Ra)... water-absorbent resin (B) having a water-retention capacity of saline solution (Rb)... Ra−Rb≧5 (g/g)
Implementation Method 3
fibrous webs from an upper side and a lower side of the absorbent layer... excellent shape retention... maintaining shape retention
Data Source
AI summary
A water-absorbent sheet structure comprises a structure in which an absorbent layer containing a water-absorbent resin (A) and a water-absorbent resin (B) is sandwiched with fibrous webs from an upper side and a lower side of the absorbent layer, characterized in that the water-absorbent resin (A) and the water-absorbent resin (B) are contained in a total amount of from 100 to 1,000 g/m2, and that the water-absorbent resin (A) and the water-absorbent resin (B) have the following properties: (1) the water-absorbent resin (A) having a water-retention capacity of saline solution (Ra) from 15 to 55 g/g; (2) the water-absorbent resin (B) having a water-retention capacity of saline solution (Rb) from 10 to 50 g/g; and (3) Ra and Rb mentioned above satisfies the relationship of the following formula: Ra−Rb≧(g/g). The water-absorbent sheet structure of 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.