Super-absorbent Polymer Composition Immobilization in Papermaking
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Solution Overview
Problem
Conventional absorbent articles face challenges with super-absorbent polymer (SAP) particles not being sufficiently immobilized, leading to migration and uneven distribution during manufacturing, shipping, and use, resulting in inconsistent absorbency and efficiency issues.
Innovation Solution
A method of applying a super-absorbent composition including a cross-linkable polymer and a cross-linking agent to a paper web during the papermaking process, utilizing various application points such as heated drums and through-air driers to increase the absorbency of absorbent articles without affecting machine runnability or fiber content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If particulate SAP is sifted into the absorbent core, then absorbent capacity is increased, but SAP particles migrate and shift during manufacturing and handling
Solution Approach 1:
The SAP particles are pre-coated with a binder solution before being incorporated into the absorbent core. This preliminary binding action prevents particle migration during subsequent manufacturing and handling operations, while still allowing the particles to provide their full absorbent capacity
Solution Approach 2:
A binder solution acts as an intermediary substance between the SAP particles and the absorbent core matrix. This binder holds the particles in place during manufacturing and handling, preventing migration while allowing the particles to function normally when exposed to fluid
2Manufacturing precision
If powdered form SAP is applied to a dry substrate, then SAP can be localized and dispersed, but SAP does not bind well to the dry sheet
Solution Approach 1:
The substrate is changed from a dry state to a moist state before SAP application. The moisture content is adjusted to an optimal range that enables both good SAP binding to the substrate and proper SAP particle dispersion, resolving the contradiction between bonding strength and distribution uniformity
3Ease of operation
If SAP particles are free to migrate during manufacturing, then handling flexibility is maintained, but handling losses and improper distribution occur
Solution Approach 1:
SAP particles are pre-coated with binder solution before handling operations. This preliminary binding prevents particle loss during transfer and handling operations, while the coating is applied in a way that does not interfere with subsequent processing steps
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 enhances the absorbent capacity of absorbent articles by up to 65% while maintaining absorbent rate, with low add-on levels of super-absorbent composition, and ensures consistent absorbency without fiber content or basis weight increases.
Implementation Method 1
Hydrophilic polymers are used because they hydrate well and effectively form hydrogen bonds with water
Implementation Method 2
SAPs are typically capable of absorbing 30 to over 200 times their weight in fluid
Implementation Method 3
Cross-linking is important because it prevents infinite swelling and eventual polymer dissolution
Implementation Method 4
utilizing various application points such as heated drums and through-air driers
Implementation Method 5
utilizing various application points such as heated drums and through-air driers
Data Source
AI summary
The invention provides a method of increasing the absorbency of an absorbent article. The method includes introducing a super-absorbent polymer composition to a paper web in a papermaking process to increase the absorbent capacity of an absorbent article made in the process. The polymer composition includes a super-absorbent polymer and a cross-linking agent applied to the paper web. The paper web is then subjected to heat in a heated drum or a through-air drier to cure or cross-link the super-absorbent polymer.