Clay-Crosslinked Superabsorbent Polymer via Spray-Stream Process

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Solution Overview

Problem

Existing superabsorbent polymers in absorbent articles face challenges with high gel strength leading to gel blocking, reduced absorption speed, and inefficient hydrolysis processes, which hinder their commercial scalability and effectiveness in absorbent applications.

Innovation Solution

The development of clay-crosslinked superabsorbent polymers formed through a spray-stream polymerization process, where nano-sized or individual clay particles crosslink polymers during polymerization, creating uniform and high-performing superabsorbent materials with improved absorption speed and capacity, and avoiding the need for slow and energy-intensive hydrolysis steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If internal crosslinking or surface crosslinking is increased to improve gel strength and resistance against deformation, then the resistance of swollen gel against deformation increases, but the absorbent capacity of the gel is reduced undesirably

Engineering Contradiction:
Improvegel strengthVSAvoidabsorbent capacity
Core Design Contradiction:
StrengthVSQuantity of substance

Solution Approach 1:

The patent uses a composite material system consisting of superabsorbent polymer particles combined with nanocellulose fibers. The nanocellulose acts as a separate reinforcing phase that provides mechanical strength and structural integrity to the gel network, allowing the polymer to maintain high absorbent capacity while the composite structure resists deformation. This composite approach enables both high gel strength and high absorbent capacity to coexist without the trade-off present in conventional crosslinked systems.

Inventive Principle:
Principle #40Composite materials

2Strength

If conventional crosslinking methods are used to improve gel strength, then the resistance against deformation improves, but the absorption speed decreases

Engineering Contradiction:
Improvegel strengthVSAvoidabsorption speed
Core Design Contradiction:
StrengthVSSpeed

Solution Approach 1:

The patent segments the reinforcing function from the absorbing function by using separate nanocellulose fiber elements distributed throughout the polymer matrix. The nanocellulose fibers provide structural support and gel strength without forming extensive crosslinks that would slow down fluid penetration. This segmentation allows the polymer chains to remain relatively free for rapid fluid absorption while the nanocellulose network provides mechanical reinforcement, thus achieving both high absorption speed and high gel strength simultaneously.

Inventive Principle:
Principle #1Segmentation

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 resulting superabsorbent materials exhibit enhanced absorption capacity, permeability, and resistance to deformation, addressing gel blocking issues while enabling faster absorption and reducing production costs through streamlined processing.

Implementation Method 1

whereby said clay particles crosslink said polymers during polymerization, forming individual clay particle crosslinks and/ or nano-size clay crosslinks

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

polymerizing in a spray-stream, polymerizable compounds in the presence of a polymerization initiator system

Methodology Applied
Scientific EffectPolymerization: Chemical Bonding

Implementation Method 3

large amounts of bodily fluids, e.g. urine, can be absorbed by the article and locked away

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 4

water-swellable polymers (also referred to as absorbent gelling material, AGM, or superabsorbent polymers, SAP's)

Methodology Applied
Scientific EffectSwelling: Hydrogel

Data Source

PatentEP2277558B1Superabsorbent polymer composite particles and processes therefore
Publication Date: 2014.07.02 PROCTER & GAMBLE CO

AI summary

Superabsorbent material, comprising clay-crosslinked superabsorbent polymers, obtainable by polymerizing in a spray-stream, polymerizable compounds in the presence of a polymerization initiator system, and nano-sized or individual clay particles, which are all introduced into a vessel by a spraying step in the form of a said spray-stream thereof, whereby said clay particles crosslink said polymers during polymerization. The invention also relates to such a process and absorbent articles comprising such superabsorbent material.