Water-Absorbing Resin Composition for Thin Diaper Color Stability
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Solution Overview
Problem
Conventional water-absorbing agents used in thin disposable diapers with reduced pulp ratios experience increased moisture absorption speed, leading to accelerated coloration over time, which is unsightly and consumer complaints.
Innovation Solution
A water-absorbing agent with surface-crosslinked resin particles having a non-uniformly pulverized shape, balanced by specific ratios of α-hydroxycarboxylic acid and chelating agents, maintains high moisture absorption properties while reducing coloration speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the pulp ratio in the absorbent body is reduced to decrease thickness, then the thickness is reduced, but the water absorption physical properties deteriorate
Solution Approach 1:
The patent changes the parameters of the water-absorbing agent by controlling particle size distribution (D10-D90 range of 0.3-1.5 mm) and surface crosslinking degree to maintain water absorption performance while reducing pulp content. This allows thickness reduction without sacrificing absorption capabilities.
Solution Approach 2:
The patent uses a composite water-absorbing agent system combining superabsorbent polymer particles with specific particle size distribution and surface crosslinked structure, replacing part of the pulp material while maintaining or improving overall absorption performance.
2Reliability
If the moisture absorbing speed is increased to improve humidity adjusting function, then the humidity adjusting function is improved, but the coloration speed increases
Solution Approach 1:
The patent applies surface crosslinking treatment to create different structural qualities between the surface and interior of the water-absorbing agent particles. The surface has higher crosslinking density to control moisture absorption speed, while the interior maintains high absorption capacity, thus improving humidity adjustment without excessive coloration.
Solution Approach 2:
The patent creates a dynamic moisture absorption process through the particle size distribution and surface crosslinking structure, allowing controlled progression of moisture uptake that balances humidity adjustment performance with reduced coloration rate.
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 an absorbent body with balanced water absorption properties and reduced coloration speed, suitable for thin diapers, addressing consumer concerns and maintaining hygiene.
Implementation Method 1
surface-crosslinked water-absorbing resin particles having a non-uniformly pulverized shape
Implementation Method 2
water-absorbing agent containing surface-crosslinked water-absorbing resin particles
Implementation Method 3
an aminocarboxylic acid-based chelating agent and/or a phosphorus-based chelating agent extracted from the water-absorbing agent
Data Source
AI summary
Provided are: a water-absorbing agent achieving, in a balanced manner, both good physical properties and a decrease in speed of coloration with lapse of time even if the water-absorbing agent has a high moisture absorbing speed due to having a large specific surface area; and an absorbent body having a low ratio of pulp and achieving, in a balanced manner, both good physical properties suitable for a thin disposable diaper and a decrease in speed of coloration with lapse of time. The absorbent body contains a hydrophilic base material and a water-absorbing agent which contains: surface-crosslinked water-absorbing resin particles having a non-uniformly pulverized shape; α-hydroxycarboxylic acid (salt); and an aminocarboxylic acid-based chelating agent and/or a phosphorus-based chelating agent, a point plotted along an x-axis that represents an amount (x1 mol %) of α-hydroxycarboxylic acid (salt) extracted from the water-absorbing agent and along a y-axis that represents an amount (y1 mmol %) of an aminocarboxylic acid-based chelating agent and/or a phosphorus-based chelating agent extracted from the water-absorbing agent being within a range that satisfies a specific relational formula of x1 and y1, the water-absorbing agent having a moisture absorbing speed of 120 mg/g/hr or more at a temperature of 40±1° C. at a relative humidity of 75±1% RH.