Superabsorbent Polymer Surface Crosslinking for Absorption Balance
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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, often leading to property deterioration due to increased 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
1Quantity of substance
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 creating a surface crosslinked layer with different crosslinking density from the inner core. The surface region has higher crosslinking density providing strength and gel structure, while the inner core maintains lower crosslinking density allowing high moisture absorption. This spatial differentiation of crosslinking density resolves the contradiction between centrifuge retention capacity and absorption under pressure.
Solution Approach 2:
The superabsorbent polymer particle is segmented into two distinct regions: a surface crosslinked layer and an inner core. The surface layer is formed by applying crosslinking agents (glycerol carbonate and/or glycerol) to the particle surface, creating a differentiated structure where each region serves different functions - the surface provides structural integrity while the core provides absorption capacity.
2Strength
If the crosslinking density is controlled high to improve absorption under pressure, then it becomes difficult to absorb moisture between the dense crosslink structures, thus deteriorating centrifuge retention capacity
Solution Approach 1:
The patent creates a gradient structure where the surface region has high crosslinking density for strength while the inner core maintains low crosslinking density for moisture absorption. This local differentiation allows each region to optimize its function without compromising the other, resolving the contradiction between absorption under pressure and centrifuge retention capacity.
3Speed
If a method of forming a porous structure on the surface of superabsorbent polymer particles using a blowing agent, or reducing a chopper hole size is applied to improve initial absorption speed, then the amount of fine particles generated in the product may increase and the strength of superabsorbent polymer may be lowered
Solution Approach 1:
The patent changes the parameter of surface crosslinking by applying crosslinking agents (glycerol carbonate and/or glycerol) to the particle surface, creating a hardened surface layer. This surface crosslinking increases surface strength and reduces fine particle generation during handling and processing, while maintaining high initial absorption speed through the porous structure formed during polymerization.
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 without increasing fine powder generation, resulting in improved absorption performance and permeability.
Implementation Method 1
conducting 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
Implementation Method 4
conducting 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
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.