Water Absorbing Polymer Particles Surface Post-Crosslinking
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Solution Overview
Problem
Current methods for producing water-absorbing polymer particles, used in hygiene products and agricultural applications, face challenges in achieving high permeability and absorption performance under pressure without compromising centrifuge retention capacity or requiring low temperature coatings.
Innovation Solution
A process involving the polymerization of monomers with acid groups, crosslinkers, and initiators, followed by surface post-crosslinking, where the particles are coated with basic salts of trivalent metal cations and monovalent carboxylic acid anions before, during, or after crosslinking, optimizing the molar ratio and using specific stabilizers to enhance liquid conduction and gel bed permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polyvalent metal cations are coated on water-absorbing polymer particles to improve liquid permeability, then gel bed permeability increases, but the particles require low temperature coatings which limits application flexibility
Solution Approach 1:
The patent changes the chemical composition parameters by using basic salts with specific molar ratios (0.6 to 1.2) of trivalent metal cations to monovalent carboxylic acid anions. This compositional parameter change enables the coating to function effectively at elevated temperatures without requiring low temperature processing, thus resolving the contradiction between improving gel bed permeability and maintaining coating temperature flexibility.
2Reliability
If crosslinker quantity is increased to improve centrifugal retention capacity, then CRC increases, but absorption capacity decreases
Solution Approach 1:
The patent applies basic salt coating before or during the surface crosslinking process rather than after. This preliminary action allows the basic salt to participate in the crosslinking mechanism itself, forming a dual-function coating that simultaneously improves centrifugal retention capacity and maintains absorption capacity by avoiding the need for excessive crosslinker quantities that would otherwise reduce absorption.
Solution Approach 2:
The patent creates a composite coating system combining basic salts (trivalent metal cations with monovalent carboxylic acid anions) with the polymer matrix. This composite material approach allows synergistic effects where the basic salt coating enhances both mechanical integrity (CRC) and functional properties (absorption) simultaneously, resolving the trade-off between these two properties.
3Stability of the object's composition
If basic salt coating is applied before or during surface crosslinking, then liquid conduction and gel bed permeability increase, but the process complexity increases
Solution Approach 1:
The patent merges the basic salt coating step with the surface crosslinking process, combining two separate operations into a single integrated process. The basic salt coating is applied before or during crosslinking, allowing both functions (improving liquid conduction and forming crosslinked structure) to be achieved simultaneously, thus reducing overall process complexity despite the additional chemical component.
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 significantly increases liquid conduction and gel bed permeability of surface post-crosslinked water-absorbing polymer particles while maintaining absorption performance under pressure, improving the overall application properties without reducing absorption capacity.
Implementation Method 1
the water-absorbing polymer particles are coated with at least one basic salt consisting of a trivalent metal cation and a monovalent carboxylic acid anion
Implementation Method 2
basic salt consisting of a trivalent metal cation and a monovalent carboxylic acid anion
Implementation Method 3
at least one crosslinker
Implementation Method 4
at least one initiator
Implementation Method 5
water-absorbing polymer particles
Implementation Method 6
water-absorbing polymer particles
Data Source
AI summary
The invention relates to producing surface post-cross-linked, water absorbing polymer particles, wherein the water absorbing polymer particles are coated with at least one base salt from a trivalent metal cation and a monovalent carboxylic acid anion before, during or after the surface post-cross-linking.