Clay-Crosslinked Coated Superabsorbent Polymer Particles
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Solution Overview
Problem
Existing superabsorbent polymers in absorbent articles face challenges in achieving high gel strength, absorption speed, and permeability while maintaining adequate absorbency, often resulting in gel blocking and premature leakage due to deformation under pressure.
Innovation Solution
The development of superabsorbent materials coated with second clay-crosslinked superabsorbent polymers, where nano-sized clay particles crosslink polymerizable compounds to form a stretchable, hydrophilic coating that enhances gel strength and absorption speed without reducing absorbency capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If internal crosslinking or surface crosslinking is increased to improve gel strength, then resistance to deformation improves, but absorbent capacity is reduced
Solution Approach 1:
The patent applies crosslinking locally only at the particle surface rather than throughout the bulk polymer. The coating layer contains crosslinked polymer chains that form a rigid shell, while the internal polymer structure remains uncrosslinked and highly absorbent. This local application of crosslinking provides surface strength to prevent deformation and gel blocking, while preserving the internal capacity to absorb fluids.
2Strength
If crosslinking is increased to improve resistance to deformation, then gel strength improves, but absorption speed decreases
Solution Approach 1:
The crosslinked structure is confined to the outer coating layer, creating a rigid shell that provides mechanical strength and resistance to deformation. The inner core polymer remains uncrosslinked with an open, porous structure that allows rapid fluid penetration and absorption. This spatial separation enables the particle to simultaneously achieve high gel strength for maintaining shape and high absorption speed for rapid fluid uptake.
3Strength
If gel strength is increased to prevent deformation, then resistance to deformation improves, but permeability decreases due to gel blocking
Solution Approach 1:
The patent creates a rigid, crosslinked outer shell that maintains particle shape and prevents excessive deformation under pressure, while the uncrosslinked inner core maintains high porosity and permeability. The rigid shell acts as a structural framework that prevents gel blocking by maintaining capillary void spaces, while allowing fluid to pass through to the absorbent inner core.
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 coated superabsorbent materials exhibit improved resistance to deformation, increased absorption speed, and enhanced liquid retention under pressure, preventing gel blocking and ensuring effective fluid distribution within absorbent articles.
Implementation Method 1
the step of polymerization of a solution or dispersion of polymerizable compounds, in the presence of a nano-sized clay particle dispersion, to obtain said second superabsorbent polymers, crosslinked by said clay particles
Implementation Method 2
superabsorbent polymers, typically hydrogel-forming water-swellable polymers... large amounts of bodily fluids, e.g. urine, can be absorbed by the article
Implementation Method 3
hydrogel-forming water-swellable polymers (also referred to as absorbent gelling material, AGM, or super-absorbent polymers, SAP's)
Data Source
AI summary
Superabsorbent material, comprising first superabsorbent polymers, coated with second clay-crosslinked superabsorbent polymers, said second clay-crosslinked superabsorbent polymers being obtainable by the step of polymerization of a solution/dispersion of polymerizable compounds and clay particles, to obtain said second superabsorbent polymers, crosslinked by said clay particles, of a weight average largest particle dimension of less than 800 nm.