Water-Absorbing Polymer Permeability via Pneumatic Conveying
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Solution Overview
Problem
The production of water-absorbing polymer particles faces challenges in achieving improved liquid transfer and absorption under pressure, with existing methods often resulting in reduced centrifuge retention capacity and absorption efficiency due to mechanical stress and inadequate surface crosslinking.
Innovation Solution
A method involving polymerization, drying, grinding, classification, and thermal surface crosslinking, with pneumatic conveying of polymer particles after grinding and before classification, optimizing the Froude number and material load to enhance particle permeability and retention capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of crosslinker is increased to improve absorption capacity, then the centrifuge retention capacity (CRC) decreases
Solution Approach 1:
The patent applies surface post-crosslinking to create a crosslinked skin layer on the particle surface while keeping the interior less crosslinked. This local differentiation allows the surface to provide structural integrity for high CRC while the interior maintains high absorption capacity through controlled crosslinking density gradients.
Solution Approach 2:
The patent performs surface post-crosslinking as a preliminary action before final product formation. By crosslinking the surface first and then controlling internal crosslinking, the method establishes a protective outer layer that maintains CRC while allowing subsequent internal crosslinking to achieve high absorption capacity.
2Ease of manufacture
If mechanical stress is applied during processing to improve particle formation, then the absorption efficiency decreases
Solution Approach 1:
The patent replaces intensive mechanical grinding with pneumatic conveying and classification to achieve particle size reduction and distribution. This substitution minimizes mechanical stress on the polymer particles while still achieving the desired particle formation, thereby preserving absorption efficiency.
Solution Approach 2:
The patent introduces pneumatic conveying as an intermediary process between grinding and classification. This intermediary method uses gas flow instead of direct mechanical contact to handle particles, reducing mechanical stress while maintaining effective particle formation and size distribution.
3Productivity
If conventional drying and grinding methods are used, then processing efficiency is improved, but liquid transfer (SFC) and permeability deteriorate
Solution Approach 1:
The patent replaces conventional mechanical grinding with pneumatic conveying and air classification systems. This substitution maintains processing efficiency through automated pneumatic handling while significantly improving liquid transfer properties by minimizing mechanical degradation of the particle structure and preserving pore integrity.
4Strength
If high crosslinking density is used to maintain particle structure, then absorption under pressure reaches maximum, but liquid conduction (SFC) decreases
Solution Approach 1:
The patent creates a crosslinked skin layer on the particle surface through surface post-crosslinking, providing structural stability and strength. The interior of the particle maintains lower crosslinking density, preserving pore structure and channels for efficient liquid conduction. This local quality differentiation resolves the contradiction between structure stability and liquid flow.
Solution Approach 2:
The patent transitions from uniform bulk crosslinking to surface-specific crosslinking, adding a dimensional aspect to the crosslinking process. By confining high crosslinking density to the surface dimension while maintaining lower density in the interior volume, the patent simultaneously achieves structural strength and liquid conduction efficiency.
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 improves liquid transfer and absorption efficiency, maintaining centrifuge retention capacity and absorption under pressure, while minimizing mechanical stress and maintaining product stability.
Implementation Method 1
the polymer particles are conveyed pneumatically after step iii) and before step iv)
Implementation Method 2
conveying takes place extremely gently as dense phase conveying (plug conveying, pulse conveying)
Implementation Method 3
v) thermal surface post-crosslinking of the classified polymer particles
Implementation Method 4
thermal surface post-crosslinking of the classified polymer particles
Implementation Method 5
i) polymerization of a monomer solution or suspension
Implementation Method 6
polymerization of a monomer solution or suspension... ii) drying of the polymer gel obtained
Implementation Method 7
ii) drying of the polymer gel obtained
Implementation Method 8
iii) grinding of the dried polymer gel into polymer particles
Implementation Method 9
iv) classification of the polymer particles
Data Source
AI summary
The invention relates to a method for producing water-absorbing polymer particles having improved permeability, comprising the steps of polymerizing, drying, grinding, classifying, and thermal surface post-cross-linking, wherein pneumatic conveying is carried out between the steps of grinding and classifying.