Superabsorbent Particle Drying Process
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Solution Overview
Problem
Existing processes for producing surface postcrosslinked superabsorbent particles struggle to achieve rapid liquid absorption and high centrifuge retention capacity while maintaining low residual monomer content.
Innovation Solution
A process involving the polymerization of an aqueous monomer solution with a small amount of initiator, followed by extrusion, drying in an air circulation belt drier with specific temperature and speed profiles, grinding, classification, and thermal surface postcrosslinking to produce superabsorbent particles with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying conditions are used, then the polymer gel can be dried, but the residual monomer content increases and liquid absorption performance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the drying temperature (120-160°C) and air circulation speed (1.2-3.0 m/s) to achieve the right balance between removing moisture and preventing monomer degradation. This specific parameter range allows complete drying while maintaining low residual monomer content and high liquid absorption performance.
Solution Approach 2:
The patent implements dynamics by using variable air circulation speeds different from conventional constant low-speed drying. The higher air circulation speed (1.2-3.0 m/s) dynamically removes moisture more efficiently while preventing monomer polymerization, thereby reducing residual monomer content and improving liquid absorption performance simultaneously.
2Reliability
If surface postcrosslinking is performed to improve centrifuge retention capacity, then CRC increases, but liquid absorption under pressure decreases
Solution Approach 1:
The patent applies local quality by performing surface postcrosslinking specifically on the particle surface rather than throughout the entire polymer matrix. This localized crosslinking at the surface level enhances centrifuge retention capacity while leaving the internal structure intact and capable of absorbing liquid under pressure, thus resolving the contradiction between CRC and absorption under pressure.
Solution Approach 2:
The patent implements preliminary action by conducting surface postcrosslinking after the polymerization and drying steps are complete. This sequential approach allows the base polymer to first achieve its optimal absorption properties, then the surface is subsequently crosslinked to provide enhanced CRC, thereby achieving both high absorption and high retention capacity.
3Productivity
If conventional polymerization with standard initiator amounts is used, then polymerization occurs, but residual monomer content increases
Solution Approach 1:
The patent applies parameter changes by significantly reducing the initiator concentration to 0.01-0.1 wt% compared to conventional amounts. This low initiator concentration slows the polymerization rate but ensures complete monomer conversion with minimal residual monomer content, achieving high manufacturing precision while maintaining acceptable productivity through optimized polymerization conditions.
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 process achieves rapid liquid absorption, high centrifuge retention capacity, and low residual monomer content in the produced superabsorbent particles, enhancing their performance in applications such as diapers and market gardening.
Implementation Method 1
an aqueous monomer solution with a small amount of initiator is polymerized to give a polymer gel
Implementation Method 2
the extruded polymer gel is dried on an air circulation belt drier
Implementation Method 3
the resultant polymer particles are ground and classified and then thermally surface postcrosslinked
Data Source
AI summary
A process for producing surface postcrosslinked superabsorbent particles, wherein an aqueous monomer solution with a small amount of initiator is polymerized to give a polymer gel, the resultant polymer gel is extruded through a die plate, the extruded polymer gel is dried on an air circulation belt drier having one or more zones, and the resultant polymer particles are ground and classified and then thermally surface postcrosslinked, wherein the temperatures of the drying gas supplied in the course of drying in the forward zones of the air circulation belt drier are from 120 to 160° C., and the speeds of the air supplied are from 1.2 to 3.0 m/s.