Nanoporous Superabsorbent Particles With Fast Uptake and Low Non-Solvent
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Solution Overview
Problem
Conventional superabsorbent materials exhibit slow absorption rates and high non-solvent levels, leading to decreased absorbency under load and unpleasant odors, with some jurisdictions imposing limits on non-solvent content.
Innovation Solution
Superabsorbent particles with controlled formation methods, including initial drying and rehydration, achieve low non-solvent levels (≤1000 ppm) and high porosity, featuring nanopores and a median size of 50 to 2,000 micrometers, enhancing absorption rates and maintaining absorbency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phase inversion is used to improve absorption rate, then absorption rate increases, but non-solvent content increases
Solution Approach 1:
The patent applies preliminary action by conducting an initial drying step before final drying to remove non-solvent. The process involves swelling the polymer in solvent, washing in non-solvent, then performing an initial drying at elevated temperature (e.g., 80-100°C) to remove大部分 non-solvent, followed by a second swelling and final drying. This preliminary removal of non-solvent prevents it from interfering with subsequent steps and achieves low final non-solvent content (<13% w/w) while maintaining fast absorption rate.
Solution Approach 2:
The patent employs periodic action through multiple alternating cycles of swelling, washing, and drying. The process repeats: swell in solvent → wash in non-solvent → initial dry → swell in solvent → wash in non-solvent → final dry. This periodic cycling allows progressive removal of non-solvent while maintaining the porous structure and fast absorption characteristics, achieving both high absorption rate and low non-solvent content.
2Reliability
If non-solvent content is reduced to improve absorbency under load, then absorbency under load improves, but absorption rate may decrease
Solution Approach 1:
The patent utilizes porous materials by maintaining a controlled porous structure throughout the phase inversion process. The porous network formed during swelling and drying provides channels for rapid fluid uptake (fast absorption rate) while the careful control of non-solvent content ensures that the pores remain functional and do not collapse. The porosity is maintained through gentle drying conditions and controlled phase inversion, achieving both fast absorption and high absorbency under load.
Solution Approach 2:
The patent applies parameter changes by carefully controlling temperature, time, and composition parameters during each step. The swelling solvent composition, washing non-solvent composition, drying temperatures (initially 80-100°C then lower for final dry), and time durations are optimized to achieve the desired balance. These parameter changes enable the material to develop low non-solvent content while maintaining the porous structure necessary for fast absorption rate and high absorbency under load.
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 particles demonstrate fast absorption rates (Vortex Time ≤30 seconds) and high absorbent capacity (10-100 g/g) without sacrificing total absorbency, while meeting regulatory non-solvent limits.
Implementation Method 1
nanopores having an average cross-sectional dimension of from about 10 to about 500 nanometers
Implementation Method 2
phase inversion of superabsorbent materials has been proposed. Phase inversion includes swelling of the superabsorbent material in a solvent, washing the swollen superabsorbent material in a non-solvent
Data Source
AI summary
Superabsorbent particles having less than 1000 ppm non-solvent, a median size of from about 50 to about 2,000 micrometers, and containing nanopores having an average cross-sectional dimension of from about 10 to about 500 nanometers are provided. The superabsorbent particles exhibit a Vortex Time of about 80 seconds or less.