Super Absorbent Polymer Surface Crosslinking for Moisture Retention

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Solution Overview

Problem

Existing super absorbent polymers (SAPs) lack superior initial absorbency and moisture retention under pressure, and do not effectively combine particle size, absorbency, and water holding properties, especially when subjected to pressure over time.

Innovation Solution

A super absorbent polymer with a SPAN value of 1.2 or less and an absorbing rate under load (ARUL) of 0.70 to 1.00, achieved through surface treatment of crosslinked polymers using a glycol-based solvent and diol-based surface crosslinking agents, with specific particle size classification and surface crosslinking conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing super absorbent polymer methods are used, then basic absorbency is achieved, but initial absorbency and moisture retention under pressure are insufficient

Engineering Contradiction:
Improvemoisture retention under pressureVSAvoidcomplexity of surface treatment process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by performing surface crosslinking treatment on the SAP particles before final application. The crosslinking agent is applied to the surface of the particles and allowed to react, creating a pre-modified surface structure that ensures reliable moisture retention under pressure when the product is eventually used.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the chemical parameters of the SAP surface by introducing crosslinking agents that form covalent bonds with surface hydroxyl groups. This chemical modification transforms the surface properties, enabling the material to maintain moisture retention under pressure conditions while managing the complexity through controlled reaction parameters.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If particle size is increased to improve water holding property, then absorbency improves, but absorbing rate under load decreases

Engineering Contradiction:
Improvewater holding capacityVSAvoidabsorbing rate under load
Core Design Contradiction:
Quantity of substanceVSSpeed

Solution Approach 1:

The patent applies local quality by creating a differentiated structure where the core maintains larger particle size for water holding capacity while the surface undergoes crosslinking treatment to enhance moisture retention. This localized modification allows the particle to exhibit both good water holding properties and improved absorbing rate under load conditions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by combining the base SAP particle material with surface-crosslinked layers. The crosslinked surface forms a distinct phase with different properties than the core, creating a composite particle that simultaneously achieves high water holding capacity and maintained absorbing rate under pressure.

Inventive Principle:
Principle #40Composite materials

3Reliability

If surface treatment is applied to improve absorbency, then initial absorbency improves, but manufacturing complexity increases

Engineering Contradiction:
Improveinitial absorbencyVSAvoidsurface treatment equipment
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a crosslinking agent as an intermediary substance that mediates between the SAP particle surface and the desired improved absorbency properties. The crosslinking agent facilitates surface modification through chemical reaction, achieving enhanced initial absorbency without requiring complex physical treatment equipment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex mechanical surface treatment systems with a chemical crosslinking process. Instead of using sophisticated physical modification equipment, the invention employs chemical reactions between crosslinking agents and surface hydroxyl groups to achieve the desired surface properties, simplifying the manufacturing system.

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

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 SAP exhibits excellent absorbency and water holding properties under pressure, providing improved comfort and performance in sanitary applications by minimizing moisture discharge over time.

Implementation Method 1

Super absorbent polymer (SAP) is a synthetic polymer material having a function of absorbing water about 5 hundred times to about 1 thousand times of the weight of itself

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

The SAP disclosed above was started to be commercialized for sanitary items and is now being widely used

Methodology Applied
Scientific EffectHydrogel: Hydrogel

Implementation Method 3

treating the surface of said hydrogel polymer by spraying a surface treatment solution including water and a surface crosslinking agent on each of the classified hydrogel polymer particles

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentUS10086361B2Super absorbent polymer and a preparation method thereof
Publication Date: 2018.10.02 LG CHEM LTD

AI summary

The present invention relates to a super absorbent polymer (SAP) and a preparation method thereof. More specifically, the present invention provides a SAP satisfying the overall properties required to a SAP and especially the superior initial absorbency and absorbing rate under load at the same time, and a preparation method thereof, by treating the surface of the SAP with a surface treatment solution including water and a diol-based or glycol-based surface crosslinking agent.