Surface-Crosslinked SAP for Low Re-Wet Sanitary Absorbents
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Solution Overview
Problem
Existing particulate water-absorbing agents in sanitary products, such as adult diapers, fail to adequately reduce re-wetting of absorbed liquids during actual use, as they are not designed to handle the pressures and conditions encountered in real-world scenarios.
Innovation Solution
A particulate water-absorbing agent containing a surface-crosslinked polyacrylic acid (salt)-based water-absorbent resin, which satisfies specific parameters for fluid retention capacity under no pressure (SRC (NP) > 50 g/g) and under high pressure (SRC (4.83 kPa) > 41.5 g/g, ensuring excellent liquid retention under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particulate water-absorbing agent is tested under standard RCAP conditions (immersion for 1 hour, pressure of 2.06 kPa), then the measurement provides a baseline absorption capacity, but it does not accurately reflect actual use conditions where absorption occurs much faster and under higher pressures
Solution Approach 1:
The patent introduces new measurement parameters (SRC at 4.83 kPa and SRC at 9.66 kPa) that change both the pressure level and time scale from the standard RCAP test. By measuring fluid retention capacity at these different parameters, the test accurately reflects actual use conditions where users experience higher pressures and faster absorption times, resolving the contradiction between standard measurement protocols and real-world performance assessment
Solution Approach 2:
The patent performs preliminary measurements of SRC at 4.83 kPa and SRC at 9.66 kPa before final product formulation. These preliminary actions allow the developers to predict actual use performance and adjust the water-absorbent resin composition accordingly, ensuring the final product meets real-world requirements without needing extensive post-market testing
2Productivity
If the particulate water-absorbing agent is designed to absorb large amounts of liquid quickly, then absorption speed improves, but liquid retention capacity under pressure deteriorates
Solution Approach 1:
The patent uses composite materials by combining water-absorbent resin with specific additives and controlling the resin's molecular structure and crosslinking density. This composite approach allows the material to achieve both rapid absorption (through hydrophilic groups) and high pressure retention (through crosslinked network structure), resolving the contradiction between absorption speed and pressure retention
Solution Approach 2:
The patent applies local quality by creating regions with different crosslinking densities within the water-absorbent resin particles. The outer regions have higher crosslinking density for pressure retention, while inner regions maintain higher porosity for rapid absorption. This spatial differentiation of material properties allows simultaneous optimization of both absorption speed and liquid retention under pressure
3Ease of operation
If the particulate water-absorbing agent is used in sanitary products subject to user weight and movement, then practical usability is achieved, but the pressure applied to the absorbent material increases beyond standard test conditions
Solution Approach 1:
The patent introduces dynamic measurement conditions that simulate the varying pressures experienced during user movement. By measuring SRC at multiple pressure points (4.83 kPa and 9.66 kPa) rather than a single static value, the test captures the dynamic pressure variations occurring during actual use, allowing the product to be optimized for practical usability under real-world stress conditions
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 agent effectively reduces re-wetting of absorbed liquids during actual use by maintaining high liquid retention capacity both without pressure and under high pressure, enhancing the performance of sanitary products.
Implementation Method 1
a water-absorbent resin (Super Absorbent Polymer: SAP) is a water-swellable, water-insoluble polymer gelling agent
Implementation Method 2
The particulate water-absorbing agent having absorbed liquid is in a swollen state
Implementation Method 3
a crosslinked polymer having 'swellability' and 'insolubility', in that the crosslinked polymer swells by absorbing liquid and forms an insoluble gel
Data Source
AI summary
Provided is a particulate water-absorbing agent that can be used for producing a sanitary product capable of further reducing the re-wetting of absorbed liquid in actual use. The subject particulate water-absorbing agent is a particulate water-absorbing agent having a fluid retention capacity of more than 50 g/g when a swollen gel obtained by bringing the particulate water-absorbing agent into contact with a 0.9% aqueous sodium chloride solution for 10 minutes is let stand for 1 minute without pressure, and having a fluid retention capacity of more than 41.5 g/g when the swollen gel is let stand for 1 minute under a pressure of 4.83 kPa.