Absorbent Core Copolymer Bonding to Prevent Gel Blocking
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Solution Overview
Problem
Existing absorbent articles face challenges with high absorbency materials causing gel blocking, leading to reduced absorption rates and leakage issues, while also requiring large quantities of wood pulp fluff for adequate absorbency.
Innovation Solution
A copolymer is irreversibly bonded onto a substrate, derived from (meth)acrylic acid, a hydrophilic monomer, and a hydrophilic crosslinking monomer, with greater than 1 wt% of the crosslinking monomer, and at least 50% of acidic functional groups neutralized with salt forming cations, to create an absorbent core with enhanced absorption capacity and rapid absorption rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high absorbency materials (superabsorbents) are incorporated to reduce bulk, then absorbent capacity per unit volume increases, but gel blocking occurs which prevents free flow of liquid and causes leakage
Solution Approach 1:
The patent employs a porous foam substrate with controlled pore structure that allows liquid to flow freely through the absorbent core. The porous architecture prevents gel blocking by providing continuous open pathways for liquid transport, ensuring that subsequent fluid insults can reach the superabsorbent particles without being blocked by swollen gel masses.
Solution Approach 2:
The invention creates a composite structure combining foam substrate with superabsorbent particles distributed throughout the porous matrix. This composite material integrates the high absorbency of superabsorbents with the liquid transport capabilities of the foam structure, achieving both high absorbent capacity and rapid absorption rates simultaneously.
2Quantity of substance
If large quantity of wood pulp fluff is used to achieve adequate absorbency, then absorbent capacity increases, but bulk and volume of the product increases
Solution Approach 1:
The patent changes the key parameter from using bulk wood pulp fluff to using high-capacity superabsorbent particles. This parameter change allows achieving the same or higher absorbent capacity with significantly reduced volume, as superabsorbents can absorb 10-50 times their weight in fluid compared to traditional wood pulp materials.
Solution Approach 2:
The composite of foam substrate and superabsorbent particles creates a high-density absorbent core that achieves superior absorbent capacity in a compact form factor, directly addressing the bulk reduction requirement while maintaining or enhancing absorbent performance.
3Volume of moving object
If superabsorbent materials are used to reduce bulk, then volume decreases, but gel blocking causes subsequent fluid insults to pool and run off resulting in leakage
Solution Approach 1:
The porous foam substrate provides continuous open-cell pathways that guide liquid flow throughout the absorbent core, preventing pooling and run-off. The interconnected pore structure ensures that subsequent fluid insults can navigate through the core to reach active superabsorbent particles, eliminating the leakage problem associated with gel blocking in conventional designs.
4Quantity of substance
If high absorbency materials are used to achieve rapid absorption, then absorbent capacity increases, but control and tailoring of absorbency capacity becomes difficult
Solution Approach 1:
The patent enables local control of absorbency by varying the concentration and distribution of superabsorbent particles within different regions of the foam substrate. This allows tailoring the absorbency capacity to specific application requirements while maintaining rapid absorption through the porous structure, providing facile control during manufacturing.
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 solution provides absorbent articles with high absorbency capacity and rapid absorption rates, reducing gel blocking and leakage, while allowing for easier control of absorbency and manufacturing through roll-to-roll processing.
Implementation Method 1
the copolymer is derived from: (i) a first monomer selected from a (meth)acrylic acid or salt thereof; (ii) a second monomer, wherein the second monomer is hydrophilic
Implementation Method 2
a second monomer, wherein the second monomer is hydrophilic
Implementation Method 3
a third monomer, wherein the third monomer is a hydrophilic crosslinking monomer, wherein at least 50% of the acidic functional groups in the core are neutralized with salt forming cations
Implementation Method 4
polymerizing the polymerizable solution to irreversibly bond a copolymer onto the first substrate forming a core
Data Source
AI summary
Described herein are absorbent articles and methods of making such articles. The articles are made by bonding a copolymer onto a substrate to form a core. The absorbent articles are particularly useful in personal care product, e.g., disposable hygiene products.