Superabsorbent Polymer Crosslinking Gradient for Retention and Permeability

Solution Overview

Problem

Existing superabsorbent polymers face a trade-off between centrifuge retention capacity and permeability, where improving one property often deteriorates the other, limiting their effectiveness in applications such as diapers and sanitary products.

Innovation Solution

A superabsorbent polymer is developed with a heat-degradable internal crosslinking agent and inorganic material, combined with a surface crosslinking layer, which allows for a crosslinking density gradient that enhances both centrifuge retention capacity and permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the crosslinking density of superabsorbent polymer is controlled high to improve permeability, then permeability is improved, but centrifuge retention capacity is deteriorated

Engineering Contradiction:

ImprovepermeabilityVSAvoidcentrifuge retention capacity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating a crosslinking density gradient within the polymer structure. The inner core region has lower crosslinking density to maintain centrifuge retention capacity, while the outer shell region has higher crosslinking density to provide shape stability and permeability. This spatial variation in crosslinking density allows both contradictory properties to coexist in different regions of the same polymer particle.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the polymer structure into distinct regions with different crosslinking characteristics. By dividing the polymer particle into an inner core and outer shell with differentiated crosslinking densities, the invention allows each segment to optimize for its specific function: the core for moisture retention and the shell for structural integrity and permeability.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the crosslinking density of superabsorbent polymer is controlled low to improve centrifuge retention capacity, then centrifuge retention capacity is improved, but permeability is deteriorated

Engineering Contradiction:

Improvecentrifuge retention capacityVSAvoidpermeability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by creating a crosslinking density gradient within the polymer structure. The inner core region has lower crosslinking density to maintain centrifuge retention capacity, while the outer shell region has higher crosslinking density to provide shape stability and permeability. This spatial variation in crosslinking density allows both contradictory properties to coexist in different regions of the same polymer particle.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the polymer structure into distinct regions with different crosslinking characteristics. By dividing the polymer particle into an inner core and outer shell with differentiated crosslinking densities, the invention allows each segment to optimize for its specific function: the core for moisture retention and the shell for structural integrity and permeability.

Inventive Principle:

Principle #1Segmentation

3Volume of stationary object

If the amount of pulp is reduced for volume decrease of diaper, then volume is decreased, but permeability requirement becomes more critical

Engineering Contradiction:

Improvediaper volumeVSAvoidpermeability

Core Design Contradiction:

Volume of stationary objectVSProductivity

Solution Approach 1:

The patent employs composite materials by combining polymer particles with differentiated crosslinking structures. The composite nature of having both low-crosslinked and high-crosslinked regions within the same particle system allows the material to provide both volume reduction and enhanced permeability, addressing the critical requirement when pulp amount is reduced.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating a crosslinking density gradient within the polymer structure. The inner core region has lower crosslinking density to maintain centrifuge retention capacity, while the outer shell region has higher crosslinking density to provide shape stability and permeability. This spatial variation in crosslinking density allows both contradictory properties to coexist in different regions of the same polymer particle.

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 polymer exhibits improved centrifuge retention capacity and permeability, maintaining shape and absorbency under load, while avoiding the inverse proportionality issues of traditional superabsorbent polymers, thus providing superior performance in hygienic applications.

Implementation Method 1

it has been confirmed that superabsorbent polymer prepared in the presence of a heat-degradable internal crosslinking agent and inorganic material may simultaneously exhibit excellent centrifuge retention capacity and permeability

Methodology Applied

Scientific EffectHeat degradation: Thermolysis

Implementation Method 2

T1 is a time (seconds) taken for a saline solution of 20 mL to pass through swollen superabsorbent polymer under pressure of 0.3 psi

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS10780417B2Super absorbent polymer

Publication Date: 2020.09.22 LG CHEM LTD

AI summary

The present invention relates to superabsorbent polymer having excellent centrifuge retention capacity and permeability. The superabsorbent polymer simultaneously exhibits excellent centrifuge retention capacity and permeability, and thus, can fundamentally solve the problems of the existing superabsorbent polymer and technical requirement of the art, and can provide various hygienic goods exhibiting more excellent properties.