Recycled Superabsorbent Polymer Purification for Uniform Absorption

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Solution Overview

Problem

The recycling of used superabsorbent polymers from diverse sanitary articles results in non-uniform performance due to the presence of impurities, making it difficult to achieve consistent absorption performance in sanitary products.

Innovation Solution

A method involving inactivation with an acidic solution, followed by oxidizing agent treatment under acidic conditions, and drying to produce a highly pure recycled superabsorbent polymer, which is then used as a raw material in superabsorbent polymer production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If used superabsorbent polymers from diverse sanitary articles are collectively recycled using conventional methods, then recycling efficiency is improved, but the uniformity of absorption performance deteriorates due to diverse impurities

Engineering Contradiction:
Improverecycling efficiencyVSAvoiduniformity of absorption performance
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by systematically adjusting chemical treatment parameters including pH levels (acidic to neutral), oxidation-reduction states (oxidizing then reducing), and ionic concentrations (divalent metal salts followed by alkali metal salts) to transform diverse impurity profiles into a standardized pure product suitable for uniform absorption performance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a multi-stage purification process that selectively removes different types of impurities at different stages: organic impurities are removed through oxidation, inorganic impurities are removed through ion exchange with divalent and alkali metal salts, achieving high purity recovery while maintaining productivity

Inventive Principle:
Principle #34Discarding and recovering

2Adaptability or versatility

If recycled superabsorbent polymers are used directly in sanitary articles, then resource utilization is improved, but the reliability of absorption performance deteriorates due to non-uniform impurity content

Engineering Contradiction:
Improveresource utilizationVSAvoidabsorption performance consistency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent performs preliminary purification actions before the recycled polymer can be used in sanitary articles. The multi-step treatment process (oxidation, ion exchange with divalent metals, ion exchange with alkali metals, drying) is completed in advance to ensure the recycled polymer meets the reliability standards required for absorption performance consistency

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces simple mechanical separation methods with chemical treatment mechanisms including oxidation reactions, ion exchange reactions, and phase changes (drying) to achieve thorough purification that ensures reliable and consistent absorption performance in the recycled polymer

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If advanced purification methods are applied to remove all impurities, then product purity is improved, but process complexity and cost increase

Engineering Contradiction:
Improvepurity of recycled superabsorbent polymerVSAvoidnumber of treatment steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the purification process into distinct functional stages: oxidation stage for organic impurities, divalent metal salt stage for certain inorganic impurities, alkali metal salt stage for remaining inorganic impurities, and drying stage. This segmentation allows each step to target specific impurity types efficiently, achieving high purity while managing process complexity through systematic division of labor

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs reagents with multiple functions: oxidizing agents that simultaneously oxidize organic impurities and prepare the polymer structure for subsequent ion exchange; divalent metal salts that remove impurities while preparing the polymer for final purification with alkali metals. This multi-functionality reduces the total number of different chemical systems needed, managing complexity while achieving high purity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This method effectively removes impurities, ensuring the recycled superabsorbent polymer can be used to produce high-quality superabsorbent polymers with uniform performance.

Implementation Method 1

an inactivation step of inactivating the used superabsorbent polymer with an acidic solution

Methodology Applied
Scientific EffectProtein denaturation:

Implementation Method 2

an oxidizing agent treatment step of treating the used superabsorbent polymer inactivated with the acidic solution with an oxidizing agent under an acidic condition

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 3

a drying step of drying the used superabsorbent polymer treated with the oxidizing agent

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP4725983A2Method for producing recycled superabsorbent polymer, method for producing superabsorbent polymer using recycled superabsorbent polymer, and recycled superabsorbent polymer
Publication Date: 2026.04.15 UNI CHARM CORP
  • EP4725983A2 patent drawingFigure 1
  • EP4725983A2 patent drawingFigure 2
  • EP4725983A2 patent drawingFigure 3

AI summary

Provided is a method that is for producing a recycled superabsorbent absorbent polymer and that allows a spent superabsorbent polymer derived from a used sanitary article to be effectively used in a product which uses a superabsorbent polymer as a raw material. This method is for producing from a used superabsorbent polymer obtained from a used sanitary article a recycled superabsorbent polymer that is a raw material for production of a superabsorbent polymer. This method comprises: a deactivation step (S30) for deactivating a used superabsorbent polymer using an acidic solution; an oxidant treatment step (S31) for treating the used superabsorbent polymer deactivated using the acidic solution using an oxidant under acidic conditions; and a drying step (S33) for drying the used superabsorbent polymer treated using the oxidant to generate a recycled superabsorbent polymer.