Water-Absorbing Polymer Particles With Localized Inorganic Shells
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Solution Overview
Problem
Existing water-absorbing polymer particles face challenges in achieving a balance between high absorption capacity, permeability, and low extractables, with conventional crosslinking methods either increasing extractables or reducing permeability.
Innovation Solution
The method involves calculating the average closest distance between crosslinkers (RXL) using Formula I to incorporate inorganic solid particles, forming areas with and without these particles, which act as barriers to limit extractables while maintaining fluid influx, using two distinct aqueous solutions and polymerization/crosslinking steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If inorganic solid particles are uniformly distributed throughout the polymer particles, then the structural strength and dimensional stability are improved, but the liquid distribution becomes non-uniform and liquid leakage increases
Solution Approach 1:
The patent applies local quality by creating non-uniform distribution of inorganic solid particles within the polymer particles. Specifically, particles are concentrated in the outer shell region while the inner core region has reduced particle concentration. This local variation in composition allows the outer shell to provide structural strength and dimensional stability, while the inner core maintains uniform liquid distribution and prevents leakage.
2Quantity of substance
If the polymer particle size is reduced to improve absorbency, then the surface area to volume ratio increases, but the structural integrity and resistance to osmotic pressure decrease
Solution Approach 1:
The patent applies segmentation by dividing the polymer particle into distinct functional regions: an inner core region and an outer shell region. The inner core provides the absorbent polymer material with high surface area to volume ratio for enhanced absorbency, while the outer shell contains concentrated inorganic solid particles that provide structural integrity and resistance to osmotic pressure. This segmented structure allows small particle sizes without sacrificing structural strength.
3Quantity of substance
If hydrophilic polymer materials are used to increase absorbency, then the liquid absorption capacity improves, but gel blocking occurs and liquid distribution becomes non-uniform
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains hydrophilic polymer materials for high liquid absorption capacity, while the outer shell has reduced polymer concentration and concentrated inorganic solid particles. This local variation prevents gel blocking in the inner core by ensuring proper liquid distribution, while the outer shell maintains structural stability and prevents non-uniform liquid distribution throughout the entire particle.
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 polymer particles exhibit improved permeability, absorption capacity, and reduced extractables, enhancing their overall performance and cost-efficiency.
Implementation Method 1
The inorganic solid particles can serve as a skeleton that maintains the shape of the polymer particles and provides mechanical strength
Implementation Method 2
When a hydrophilic polymer or copolymer is in the form of particles or crosslinked particles, the particles can absorb liquid by capillary action and/or osmosis, expand, and form a gel
Implementation Method 3
the particles can absorb liquid by capillary action and/or osmosis, expand, and form a gel
Data Source
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AI summary
A method for making water-absorbing polymer particles is provided and consists of a first aqueous polymerization solution comprising crosslinkers, polymerizable monomers and/or oligomers and inorganic solid particles, and a second aqueous solution comprising inorganic solid particles, crosslinkers and either polymerizable monomers and/or oligomers, or crosslinkable polymers. The average closest distance between two neighboring crosslinkers (RXL) from the first aqueous polymerization solution or from the second aqueous solution for a specific X-load of the water-absorbing polymer particle is calculated via the formula (I)