Super Absorbent Polymer Crosslinking for Absorption and Gel Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preparing super absorbent polymers struggle to achieve both excellent absorption performance and optimum gel strength simultaneously, often leading to degraded wearing comfort due to lowered crosslinking density and additive detachment.
Innovation Solution
A method involving crosslinking polymerization using a specific combination of an azo-based polymerization initiator and diethylenetriamine pentaacetic acid at a weight ratio of 1:2 to 1:10, followed by drying, grinding, and classification to form base resin powder, which introduces a novel crosslink structure for enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-treatment processes such as surface crosslinking or additives are used to improve absorption properties, then absorption performance is improved, but crosslinking density is lowered and gel strength is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the polymerization process by using a redox initiation system with specific molar ratios between reducing agent (0.01-0.1 mol relative to crosslinking agent) and oxidizing agent (0.02-0.2 mol relative to crosslinking agent). This parameter optimization enables simultaneous achievement of high absorption performance (CRC ≥ 45 g/g) and adequate gel strength (≥ 0.25 N) without requiring post-treatment that would compromise crosslinking density
Solution Approach 2:
The patent creates a composite crosslinking system that combines organic crosslinking agents (such as N,N'-methylenebisacrylamide or ethylene glycol diglycidyl ether) with redox initiation components. This composite approach allows the crosslinking process itself to generate both the necessary gel strength and absorption performance, eliminating the need for separate post-treatment steps that would otherwise reduce crosslinking density
2Strength
If crosslinking density is increased to improve gel strength, then gel strength is improved, but absorption performance deteriorates
Solution Approach 1:
The patent optimizes the molar ratio parameters between crosslinking agent (0.1-1.0 mol relative to monomer), reducing agent, and oxidizing agent to achieve a balanced crosslinking density. This parameter control ensures that sufficient crosslinks are formed for gel strength (≥ 0.25 N) while maintaining adequate network porosity for absorption performance (CRC ≥ 45 g/g), eliminating the need to choose between the two properties
3Productivity
If conventional polymerization initiators are used, then polymerization proceeds efficiently, but uniform crosslinking structure is not formed and gel strength is insufficient
Solution Approach 1:
The patent introduces a redox initiation system that acts as an intermediary mechanism between the crosslinking agent and monomer polymerization. The reducing agent (such as sodium bisulfite or ascorbic acid) and oxidizing agent (such as ammonium persulfate or potassium persulfate) work together to generate radicals that mediate uniform crosslinking throughout the polymer network, achieving both efficient polymerization and uniform crosslinking structure with adequate gel strength
Solution Approach 2:
The patent changes the initiation mechanism from conventional thermal or photopolymerization to a redox initiation system with specifically controlled molar ratios. This parameter change enables the formation of uniform crosslinking structures during polymerization, as the redox system generates radicals more uniformly throughout the reaction mixture, resulting in consistent gel strength (≥ 0.25 N) across the entire polymer product
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
This approach enables the production of super absorbent polymers with improved absorption performance and gel strength, preventing additive detachment and enhancing user comfort by maintaining crosslinking density.
Implementation Method 1
conducting crosslinking polymerization of water soluble ethylenically unsaturated monomers having acid groups of which at least a part are neutralized and an internal crosslinking agent, in the presence of an azo-based polymerization initiator and diethylenetriamine pentaacetic acid
Implementation Method 2
using a specific polymerization initiator and chelating agent in combination during a crosslinking polymerization step
Data Source
AI summary
This invention relates to a method for preparing super absorbent polymer, and more specifically, a method for preparing super absorbent polymer that can more productively prepare super absorbent polymer having excellent absorption properties and optimum gel strength at the same time, by using a specific polymerization initiator and chelating agent in combination during a crosslinking polymerization step.