Phosphinate Acrylic Polymers for Crosslinked Cellulose Fiber Bulk
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Solution Overview
Problem
Existing methods for crosslinking cellulose fibers in fluff pulp to enhance bulk and absorbency in absorbent articles face challenges such as toxicity issues with free aldehydes and limited storage stability, and require special handling to prevent viscosity buildup.
Innovation Solution
Aqueous compositions comprising acrylic acid polymers with phosphinate groups and polyethylene glycols are used to treat fluff pulp, improving crosslinking efficiency and reducing the amount of polyacrylic acid needed, while maintaining mechanical performance and stability, allowing for high solids content storage without viscosity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polycarboxylic acids such as citric acid or polyacrylic acid are used as crosslinking agents for fluff pulp, then crosslinking function is achieved, but desirable fluff pulp bulk remains elusive
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking agent by using phosphinate-containing acrylic acid polymers with specific molecular weights (1,000-6,000) and controlled phosphinate group content (2-20 wt%). These parameter changes enable effective crosslinking while achieving the desired fluff pulp bulk, resolving the contradiction between crosslinking function and bulk enhancement.
2Reliability
If glycol and dialdehyde are used to treat cellulosic fiber webs, then resilient hydrophilic fibers are produced, but free aldehyde remains in the product causing toxicity concerns
Solution Approach 1:
The patent extracts and eliminates the harmful dialdehyde component from the crosslinking system. By using phosphinate-containing acrylic acid polymers as the sole crosslinking agent, the method removes the source of free aldehyde while maintaining fiber resilience and hydrophilicity through the phosphinate crosslinking mechanism.
Solution Approach 2:
The patent replaces the problematic dialdehyde crosslinking system with a safer, water-based phosphinate polymer system that does not generate persistent harmful byproducts, effectively substituting a toxic short-lived reactive agent with a safer alternative.
3Ease of operation
If phosphinate telomers of polyacrylic acid crosslinkers are used, then enhanced flow and penetration into cellulosic fibers is achieved, but viscosity buildup occurs during storage requiring special handling
Solution Approach 1:
The patent changes the molecular weight parameter of the phosphinate-containing polymer to a specific range (1,000-6,000) that balances flow and penetration capabilities with storage stability. This parameter optimization allows the composition to maintain low viscosity during storage while still achieving effective fiber penetration and crosslinking.
4Quantity of substance
If high solids content compositions are formulated, then storage efficiency is improved, but viscosity buildup prevents stable storage
Solution Approach 1:
The patent optimizes the molecular weight and phosphinate group content parameters of the acrylic acid polymer to enable high solids content formulations (achieving effective crosslinking at lower polymer concentrations) while maintaining storage stability. The controlled polymer structure prevents excessive intermolecular interactions that would cause viscosity buildup.
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 intrafiber crosslinked cellulose fibers with enhanced bulk, absorbency, and reduced toxicity, suitable for high-loft, low-density absorbent structures like diapers, with improved storage and handling characteristics.
Implementation Method 1
aqueous compositions comprising (i) one or more acrylic acid polymers containing phosphinate groups... to form individualized, intrafiber crosslinked cellulosic fibers
Implementation Method 2
ability to penetrate into the cellulosic fibers
Data Source
AI summary
The present invention provides aqueous compositions for treating fluff pulp comprising (i) one or more acrylic acid polymers containing phosphinate groups and having a weight average molecular weight of from 1,000 to 6,000 and (ii) from 5 to 50 wt. %, based on the total solids weight of the aqueous compositions, of one or more polyethylene glycols, having a formula weight of from 150 to 7,000, or, preferably, from 200 to 600. The present invention also provides individualized, intrafiber crosslinked cellulosic fibers comprising the cellulosic fiber and, in cured form, the aqueous compositions, as well as methods of making the individualized, intrafiber crosslinked cellulosic fibers.