Water-Absorbent Polymer Particles Thermal Post-Treatment
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Solution Overview
Problem
Existing methods for producing water-absorbing polymer particles often result in high residual monomer content and inadequate control over water content, which affects their performance and stability.
Innovation Solution
A method involving polymerizing drops of a monomer solution in a gas phase, followed by thermal post-treatment in a fluidized state with controlled humidity and temperature to achieve a water content of at least 5% by weight, ensuring effective removal of residual monomers and maintaining optimal moisture levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal post-treatment is performed at high temperature to remove residual monomer, then residual monomer content decreases, but water content changes excessively
Solution Approach 1:
The patent applies parameter changes by precisely controlling both temperature and relative humidity of the gas stream during thermal post-treatment. By adjusting these parameters together (temperature of 60-150°C combined with relative humidity of 20-95%), the process achieves effective residual monomer removal while maintaining water content changes within 40%, resolving the contradiction between monomer removal efficiency and water content stability.
Solution Approach 2:
The patent introduces a controlled gas stream as an intermediary medium that carries water vapor to maintain humidity during heating. This gas stream acts as a mediator that enables simultaneous heat transfer and moisture control, allowing residual monomer removal without excessive water loss from the polymer particles.
2Manufacturing precision
If thermal post-treatment is performed for long duration to ensure complete monomer removal, then residual monomer content decreases, but production time increases
Solution Approach 1:
The patent reduces processing time by optimizing the combination of temperature (60-150°C) and relative humidity (20-95%) parameters. This optimized parameter set achieves effective residual monomer removal (reducing to below 0.1 wt.%) within 5-120 minutes, significantly shorter than conventional methods, while maintaining water content stability and ensuring complete monomer removal.
3Reliability
If water content is maintained at high level to ensure absorption performance, then absorption properties improve, but residual monomer content increases
Solution Approach 1:
The controlled gas stream serves as an intermediary that enables the simultaneous achievement of high water content (5-40 wt.%) and low residual monomer content (<0.1 wt.%). The gas stream delivers moisture to maintain absorption performance while the controlled thermal environment ensures complete monomer removal, resolving the contradiction between these two requirements.
Solution Approach 2:
The patent achieves the co-optimization of water content and residual monomer content by precisely controlling the parameters of thermal post-treatment. The combination of temperature (60-150°C), relative humidity (20-95%), and treatment time (5-120 minutes) creates optimal conditions where both high water content for absorption performance and low residual monomer content are achieved simultaneously.
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 method significantly reduces residual monomer content and maintains a stable water content, enhancing the centrifuge retention capacity and absorption properties of the polymer particles.
Implementation Method 1
thermally post-treated in a fluidized state in the presence of a gas stream at a temperature of at least 60°C
Implementation Method 2
the gas stream has a relative humidity of at least 20% at a temperature of less than 100°C or contains at least 0.25 kg of water vapor per kg of dry gas at a temperature of 100°C or more
Implementation Method 3
the post-treatment is carried out for at least 5 minutes, wherein the gas stream has a relative humidity of at least 20%
Implementation Method 4
the water content of the polymer particles changes by less than 40% during the post-treatment
Data Source
AI summary
The invention relates to a method for producing water-absorbent polymer particles by the polymerisation of droplets of a monomer solution in a surrounding gas phase. According to the invention, the resultant polymer particles have a water content of at least 5 % by weight and are thermally re-treated in a fluidised state in the presence of water vapour at a temperature of at least 60°C.