Superabsorbent Polymer Surface Crosslinking for Permeability and Retention

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Solution Overview

Problem

Existing superabsorbent polymers face challenges in achieving high absorption rate and liquid permeability while maintaining high centrifuge retention capacity and absorbency under load, which are conflicting properties, making it difficult to satisfy the demand for slim and effective hygiene products.

Innovation Solution

A method for preparing superabsorbent polymers involving the use of acrylic acid as a monomer, optimized internal crosslinking agents, and controlled polymerization conditions to achieve a hydrogel polymer with specific gel strength, followed by coarse pulverization and surface crosslinking to enhance physical properties such as centrifuge retention capacity, absorbency under load, liquid permeability, and absorption rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If surface crosslinking reaction is performed by adding silica or clay, then liquid permeability is improved, but centrifuge retention capacity and absorbency under load are reduced

Engineering Contradiction:

Improveliquid permeabilityVSAvoidcentrifuge retention capacity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the crosslinking agent system by using a specific combination of carbodiimide (0.1-5 wt% relative to superabsorbent polymer) and silane (0.1-5 wt% relative to superabsorbent polymer) instead of traditional silica or clay additives. This parameter change achieves improved liquid permeability while maintaining centrifuge retention capacity through synergistic chemical crosslinking that preserves particle integrity.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If surface crosslinking reaction is performed by adding silica or clay, then liquid permeability is improved, but absorbency under load is reduced

Engineering Contradiction:

Improveliquid permeabilityVSAvoidabsorbency under load

Core Design Contradiction:

Use of energy by moving objectVSQuantity of substance

Solution Approach 1:

The invention creates a composite crosslinking system combining carbodiimide and silane agents that work synergistically on the superabsorbent polymer surface. This composite approach achieves improved liquid permeability through controlled surface modification while maintaining absorbency under load by preventing excessive surface hardening and preserving the polymer's swelling capacity.

Inventive Principle:

Principle #40Composite materials

3Reliability

If gel strength is increased to maintain particle integrity, then centrifuge retention capacity is improved, but absorption rate and liquid permeability are reduced

Engineering Contradiction:

Improvecentrifuge retention capacityVSAvoidabsorption rate

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The invention applies local quality modification by performing surface crosslinking that creates a differentiated structure: a crosslinked surface layer that provides mechanical strength and centrifuge retention capacity, while the internal polymer matrix remains uncrosslinked and highly absorbent. This local differentiation allows the particle surface to resist breakdown during centrifugation while maintaining high absorption rate and liquid permeability through the porous internal structure.

Inventive Principle:

Principle #3Local quality

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 results in superabsorbent polymers with balanced physical properties, including high absorption rate and liquid permeability without reducing centrifuge retention capacity or absorbency under load, enabling the production of thinner, more effective hygiene products.

Implementation Method 1

polymerizing an acrylic acid-based monomer aqueous solution

Methodology Applied

Scientific EffectPolymerization: Chemical Bonding

Implementation Method 2

internal crosslinking agents, and controlled polymerization conditions to achieve a hydrogel polymer with specific gel strength, followed by coarse pulverization and surface crosslinking

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentEP3067370B2Method for preparing super-absorbent resin

Publication Date: 2021.12.29 LG CHEM LTD

AI summary

Provided is a method of preparing a superabsorbent polymer. According to the method of preparing the superabsorbent polymer of the present invention, provided is a superabsorbent polymer having improved physical properties, in which the superabsorbent polymer has improved absorption rate and liquid permeability without reduction in centrifuge retention capacity or absorbency under load.