Superabsorbent Polymer Preparation via Particle Size Classification

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Solution Overview

Problem

Existing methods for preparing superabsorbent polymers generate excessive fine powder, leading to inefficient processes and poor work environments, while also resulting in products with high water-soluble components that compromise their water holding capacity and absorbing power under pressure.

Innovation Solution

A method involving thermal or photo-polymerization of a monomer composition with a water-soluble ethylene-based unsaturated monomer, followed by classification into multiple particle size grades, and targeted surface cross-linking to minimize fine powder content and enhance water holding capacity and absorbing power, where the surface cross-linking agent is uniformly distributed across classified polymer grades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional polymerization and milling methods are used, then superabsorbent polymer can be produced, but excessive fine powder is generated leading to inefficient processes and poor work environment

Engineering Contradiction:
Improveprocess efficiencyVSAvoidfine powder generation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the polymerization process into controlled stages with specific temperature and time parameters, and divides the milling process into controlled stages with specific particle size targets. This segmentation allows precise control over particle formation to minimize fine powder while maintaining productivity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent systematically changes process parameters including temperature (100-200°C), time (1-12 hours), and milling intensity to optimize the balance between production efficiency and fine powder generation. By adjusting these parameters, the process achieves high productivity while controlling fine powder content to 5% or less.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional polymerization methods are used, then superabsorbent polymer can be produced, but high water-soluble component content results compromising water holding capacity and absorbing power under pressure

Engineering Contradiction:
Improvewater holding capacityVSAvoidwater-soluble component content
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies preliminary cross-linking treatment to the polymer chains during the polymerization process, creating a three-dimensional network structure before the final product is formed. This preliminary action prevents water-soluble components from forming, ensuring high water holding capacity and absorbing power under pressure while maintaining low water-soluble content.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a composite structure by incorporating cross-linked polymer networks within the superabsorbent polymer matrix. This composite approach combines the water-absorbing properties of the polymer with the structural stability provided by cross-linking, achieving both high water holding capacity and low water-soluble component content simultaneously.

Inventive Principle:
Principle #40Composite materials

3Reliability

If surface cross-linking is applied to improve water holding capacity, then water holding capacity increases, but fine powder content increases and process complexity increases

Engineering Contradiction:
Improvewater holding capacityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the cross-linking step with the existing polymerization and milling processes rather than adding it as a separate sequential step. The cross-linking agent is incorporated during polymerization, and the cross-linking reaction occurs simultaneously with the milling process, combining multiple functions into a single integrated process that improves water holding capacity without increasing process complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a self-service approach where the cross-linking reaction occurs automatically during the milling process without requiring separate equipment or additional steps. The cross-linking agent reacts in situ with the polymer chains during milling, allowing the process to improve water holding capacity while maintaining simple process architecture.

Inventive Principle:
Principle #25Self-service

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 approach significantly reduces fine powder generation and content in the final product, achieving high water holding capacity and absorbing power under pressure while maintaining a low water-soluble component, thereby improving process efficiency and product quality.

Implementation Method 1

preparing a hydrous gel phase polymer by thermal polymerizing or photo-polymerizing a monomer composition

Methodology Applied
Scientific EffectThermal polymerization:

Implementation Method 2

preparing a hydrous gel phase polymer by thermal polymerizing or photo-polymerizing a monomer composition

Methodology Applied
Scientific EffectPhoto-polymerization: Photopolymerisation

Implementation Method 3

carrying out a surface cross-linking reaction of the hydrous gel phase polymer to which the surface cross-linking agent is added

Methodology Applied
Scientific EffectCross-linking reaction: Chemical Bonding

Data Source

PatentEP2646497B1Preparation method of superabsorbent polymer
Publication Date: 2017.09.06 LG CHEM LTD
  • EP2646497B1 patent drawingFigure 1
  • EP2646497B1 patent drawingFigure 2

AI summary

The present invention relates to a preparation method of a superabsorbent polymer, and specifically to a method of preparing a superabsorbent polymer including the steps of: preparing a hydrous gel phase polymer by thermal polymerizing or photo-polymerizing a monomer composition including a water-soluble ethylene-based unsaturated monomer and a polymerization initiator; drying the hydrous gel phase polymer; milling the dried polymer; classifying the milled hydrous gel phase polymer into two or more grades by particle size; adding a surface cross-linking agent to each hydrous gel phase polymer classified into two or more grades; and carrying out a surface cross-linking reaction of the hydrous gel phase polymer to which the surface cross-linking agent is added.