Superabsorbent Polymer Dual Crosslinking Rewetting
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Solution Overview
Problem
Superabsorbent polymers face challenges in simultaneously enhancing centrifuge retention capacity and absorbency under pressure while maintaining liquid permeability, leading to rewetting and urine leakage issues in hygiene products.
Innovation Solution
A method involving the preparation of a superabsorbent polymer through crosslinking polymerization of acrylic acid-based monomers, followed by surface modification with a mixture of epoxy-based surface crosslinking agents of different equivalent weights, and incorporation of an inorganic filler to form a double surface-modified layer, improving the polymer's absorption properties and preventing rewetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the overall crosslinking density of the superabsorbent polymer is controlled to be low, then centrifuge retention capacity becomes relatively high, but a crosslinking structure becomes loose and gel strength becomes low, leading to a reduction in absorbency under pressure
Solution Approach 1:
The patent applies local quality by creating a dual-crosslinking structure where the internal crosslinking density is kept low (for high CRC) while the surface crosslinking density is high (for high AUP). This is achieved by introducing a surface crosslinking agent that reacts preferentially with carboxyl groups on the particle surface, forming a dense surface crosslinked layer that provides gel strength without compromising the overall low crosslinking density needed for centrifuge retention capacity.
Solution Approach 2:
The patent uses composite materials by combining the base superabsorbent polymer particles with a surface crosslinking agent (epoxy compound or silane compound). This creates a composite structure where the core maintains low crosslinking for high CRC while the surface layer provides high crosslinking density for high AUP, effectively resolving the contradiction between these two properties.
2Strength
If the crosslinking density is controlled to be high, then absorbency under pressure is improved, but water is hardly absorbed between compact crosslinking structures, leading to a reduction in basic centrifuge retention capacity
Solution Approach 1:
The patent applies local quality by creating a dual-crosslinking structure where the internal crosslinking density is kept low (for high CRC) while the surface crosslinking density is high (for high AUP). This is achieved by introducing a surface crosslinking agent that reacts preferentially with carboxyl groups on the particle surface, forming a dense surface crosslinked layer that provides gel strength without compromising the overall low crosslinking density needed for centrifuge retention capacity.
Solution Approach 2:
The patent uses composite materials by combining the base superabsorbent polymer particles with a surface crosslinking agent (epoxy compound or silane compound). This creates a composite structure where the core maintains low crosslinking for high CRC while the surface layer provides high crosslinking density for high AUP, effectively resolving the contradiction between these two properties.
3Quantity of substance
If the superabsorbent polymer absorbs liquid, then absorption performance is improved, but a pressure by a user's weight causes a rewetting phenomenon where absorbed liquid leaks out again
Solution Approach 1:
The patent applies parameter changes by modifying the surface crosslinking density parameter of the superabsorbent polymer. By introducing surface crosslinking, the gel strength at the particle surface is enhanced, which prevents the polymer network from collapsing under pressure and eliminates the rewetting phenomenon. This allows the polymer to maintain high absorption performance while achieving reliable rewetting suppression under user weight pressure.
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 resulting superabsorbent polymer exhibits enhanced centrifuge retention capacity, absorbency under pressure, and liquid permeability, effectively preventing rewetting and urine leakage, maintaining excellent absorption performance even under pressure.
Implementation Method 1
performing surface modification of the base resin by raising the temperature of the mixture of step 2, wherein the epoxy-based surface crosslinking agent includes a first epoxy crosslinking agent having an epoxy equivalent weight of 100 g/eq or more to less than 130 g/eq and a second epoxy crosslinking agent having an epoxy equivalent weight of 130 g/eq to 200 g/eq
Implementation Method 2
A superabsorbent polymer (SAP) is a synthetic polymeric material capable of absorbing moisture from 500 to 1000 times its own weight
Data Source
AI summary
Provided are a superabsorbent polymer and a preparation method thereof. The method of preparing the superabsorbent polymer of the present invention may provide a superabsorbent polymer having improved rewetting property and liquid permeability.