Superabsorbent Polymer Surface Crosslinking for Fast, Strong Absorption
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Solution Overview
Problem
Existing superabsorbent polymers face challenges in simultaneously improving centrifuge retention capacity and absorption under pressure while maintaining permeability and initial absorption speed without increasing fine powder content.
Innovation Solution
A method involving crosslinking polymerization of water-soluble ethylenically unsaturated monomers with internal and surface crosslinking agents, using a cyclic carbonate-based compound and sodium dodecyl sulfate to form a surface crosslink layer on superabsorbent polymer particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the whole crosslinking density of superabsorbent polymer is controlled low, then centrifuge retention capacity becomes relatively high, but the crosslink structure becomes loose and gel strength decreases, thus deteriorating absorption under pressure
Solution Approach 1:
The patent applies local quality by introducing a dual crosslinking structure where internal crosslinking agents provide overall network stability while surface crosslinking agents create localized dense crosslink structures on the particle surface. This allows the interior to maintain lower crosslinking density for good centrifuge retention capacity while the surface has higher crosslinking density for maintaining gel strength and absorption under pressure.
Solution Approach 2:
The patent uses composite materials by combining two types of crosslinking agents: internal crosslinking agents (such as polyethylene glycol diacrylate) and surface crosslinking agents (such as polyethylene glycol dimethacrylate with molecular weight 100-1000). This composite crosslinking system enables simultaneous optimization of both centrifuge retention capacity and absorption under pressure properties.
2Strength
If the crosslinking density is controlled high to improve absorption under pressure, then gel strength increases, but it becomes difficult to absorb moisture between the dense crosslink structures, thus deteriorating centrifuge retention capacity
Solution Approach 1:
The patent applies local quality by creating a spatial differentiation in crosslinking density: the interior of the polymer particles maintains lower crosslinking density to preserve moisture absorption capability and centrifuge retention capacity, while the surface layer has higher crosslinking density to provide gel strength and absorption under pressure resistance.
Solution Approach 2:
The patent employs composite materials through the combination of internal and surface crosslinking agents with different molecular weights and crosslinking characteristics. The internal crosslinking agents create a relaxed network in the particle core, while surface crosslinking agents form a dense crosslinked layer on the particle surface, achieving property optimization through material composition.
3Speed
If the surface area of superabsorbent polymer is broadened to improve initial absorption speed, then absorption speed increases, but the amount of fine particles generated increases and the strength of superabsorbent polymer is lowered
Solution Approach 1:
The patent applies preliminary action by pre-forming a dense crosslinked surface layer on the polymer particles before they are used in the final product. This surface crosslinking layer is created in advance through surface crosslinking treatment, which prevents particle fragmentation and fine powder generation during subsequent processing and use, while still allowing rapid initial absorption through the hydrophilic surface.
Solution Approach 2:
The patent uses parameter changes by controlling the molecular weight of surface crosslinking agents (100-1000) and adjusting crosslinking conditions to create an optimal surface layer thickness and density. This controlled parameter adjustment increases surface area for rapid absorption without excessive particle size reduction that would compromise strength.
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 enhances centrifuge retention capacity, absorption under pressure, and initial absorption speed while minimizing fine powder generation, resulting in improved absorption performance.
Implementation Method 1
crosslinking polymerization of water soluble ethylenically unsaturated monomers having acid groups of which at least a part are neutralized, in the presence of an internal crosslinking agent, to form hydrogel polymer
Implementation Method 2
surface crosslinking the base resin powder in the presence of a surface crosslinking solution comprising a cyclic carbonate-based surface crosslinking agent and sodium dodecyl sulfate to form superabsorbent polymer particles
Implementation Method 3
Super absorbent polymer (SAP) is synthetic polymer material that can absorb moisture of 500 to 1000 times of self-weight
Data Source
AI summary
There are provided a superabsorbent polymer composition and a method for preparing the same, more specifically, a superabsorbent polymer composition exhibiting excellent absorption performance and a method for preparing the same.