Agglomerated Superabsorbent Polymer Particles via Multivalent Salts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing agglomerated superabsorbent polymer particles face challenges in achieving a balance between absorption speed, permeability, and capacity, often resulting in either rapid absorption with reduced capacity or increased permeability at the expense of swelling ability, particularly for smaller particles.
Innovation Solution
The use of multivalent salts with a valence of three or higher, such as aluminum sulfate, to form agglomerated superabsorbent polymer particles, which enhances initial absorption speed and permeability while maintaining capacity by establishing strong ionic interactions between particles, reducing compaction, and allowing for higher surface area absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If surface cross-linking is applied to increase permeability, then permeability is improved, but capacity is reduced
Solution Approach 1:
The patent applies surface cross-linking only to the outer layer of the superabsorbent polymer particles, leaving the core region uncross-linked. This creates a gradient structure where the surface has high stiffness and permeability, while the core maintains softness and high absorption capacity. The local differentiation of cross-linking density resolves the contradiction between permeability and capacity.
Solution Approach 2:
The patent controls the cross-linking parameters (cross-linker concentration, reaction time, temperature) to achieve optimal surface cross-linking density. By precisely adjusting these parameters, the surface becomes sufficiently stiff for permeability while avoiding excessive cross-linking that would reduce capacity. This parameter optimization resolves the trade-off between the two properties.
2Speed
If particle size is reduced to increase surface area, then absorption speed is improved, but permeability deteriorates due to gel blocking
Solution Approach 1:
The patent creates a local quality difference between the particle surface and core, where the surface is cross-linked to maintain structural integrity and prevent gel blocking, while the core remains uncross-linked to provide absorption capacity. This local differentiation allows small particles to maintain both fast absorption speed and good permeability.
Solution Approach 2:
The patent applies surface cross-linking as a preliminary treatment before the particles are used in absorbent articles. This pre-treatment strengthens the particle surfaces to resist deformation and prevent gel blocking during subsequent swelling, ensuring that even small particles maintain high permeability throughout their service life.
3Manufacturing precision
If agglomerates are formed to reduce fine particles, then particle size control is improved, but absorption speed may be reduced
Solution Approach 1:
The patent creates agglomerates with a specific internal structure where individual particles maintain their surface cross-linked/uncross-linked core structure. This local quality preservation within agglomerates ensures that the fast absorption characteristics of small particles are retained, while the agglomerate structure provides good particle size control and reduced fines.
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 resulting agglomerated superabsorbent polymer particles exhibit fast initial absorption, high permeability, and improved capacity, reducing leakage in absorbent articles and maintaining stability in both water and bodily liquids.
Implementation Method 1
The use of multivalent salts with a valence of three or higher, such as aluminum sulfate, to form agglomerated superabsorbent polymer particles, which enhances initial absorption speed and permeability while maintaining capacity by establishing strong ionic interactions between particles
Implementation Method 2
The superabsorbent polymer particles need first to be able to absorb the liquid exudates fast. The absorption speed of superabsorbent polymer particles has generally been characterized in the prior art by measuring the Free Swell Rate (FSR) of the particles.
Implementation Method 3
Gel blocking can occur in the absorbent core when swelling superabsorbent polymer particles block the void spaces between the particles.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to agglomerated superabsorbent polymer particles which have been agglomerated by using a multivalent salt having a valence of three or higher. Due to agglomeration, the mean average particle size increase by at least 25% compared to the mean average particle size of the non-agglomerates superabsorbent polymer particles.