Cationic Vinyl Copolymer Dispersion for Flushable Nonwoven Binders
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Solution Overview
Problem
Existing ion-sensitive and sulfonate anion modified acrylic acid terpolymers used as binders for disposable products face limitations in dispersability in hard water, increased dry sheet stiffness, reduced sheet wettability, stickiness, and high production costs, along with environmental concerns from hazardous air pollutants and volatile organic compounds.
Innovation Solution
A method of solution copolymerizing vinyl-functional cationic monomers with hydrophobic vinyl monomers in a mixture of organic solvents and water, using acetone as a preferred solvent, which is recycled to enhance molecular weight and reduce environmental impact, resulting in ion-triggerable cationic polymers suitable for use in flushable personal care products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If acrylic acid-based terpolymers are used as binders, then in-use strength is adequate, but dispersability in hard water is poor
Solution Approach 1:
The invention changes the chemical composition parameters of the polymer by incorporating sulfonate groups (via AMPS monomer) and controlling the ratio of acrylic acid to other monomers. This chemical parameter change enables the polymer to maintain adequate in-use strength while significantly improving dispersability in hard water containing calcium and magnesium ions.
Solution Approach 2:
The invention creates a composite polymer structure combining acrylic acid units with sulfonate-containing AMPS units. This composite material approach allows the polymer to exhibit both binding strength (from acrylic acid) and hard water dispersability (from sulfonate groups), resolving the contradiction between these two properties.
2Adaptability or versatility
If sulfonate anion modified acrylic acid terpolymers are used, then dispersability in hard water is improved, but dry sheet stiffness increases
Solution Approach 1:
The invention optimizes the concentration of sulfonate groups by controlling the AMPS monomer content within specific ranges (0.1-10% of total monomers). This parameter optimization maintains hard water dispersability while preventing excessive increase in dry sheet stiffness, achieving a balance between the two properties.
3Adaptability or versatility
If ion-sensitive polymers are used as binders, then flushability is enabled, but initial sheet wettability is reduced
Solution Approach 1:
The invention adjusts the hydrophilic-hydrophobic balance by controlling acrylic acid content (1-20% of total monomers) and incorporating hydrophobic monomers (butyl acrylate, 2-ethylhexyl acrylate) in specific ratios. This parameter optimization enables the polymer to trigger dissolution in water (flushability) while maintaining adequate initial wettability for binder function.
4Productivity
If conventional polymerization methods are used, then polymer production is achieved, but hazardous air pollutants and volatile organic compounds are released
Solution Approach 1:
The invention replaces conventional organic solvent-based polymerization with aqueous-phase polymerization, using water as the continuous phase. This creates a more environmentally friendly reaction environment that eliminates or significantly reduces the release of hazardous air pollutants and volatile organic compounds while maintaining productive polymer synthesis.
Solution Approach 2:
The invention changes the solvent system parameter from organic-based to water-based, transforming the polymerization environment. This parameter change enables productive polymer production while eliminating the harmful emissions associated with conventional organic solvent methods.
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 method produces polymers with high molecular weight, maintaining integrity during use and dispersing in hard water, reducing production costs, and minimizing environmental harm, while ensuring the polymers are effective as binders for nonwoven fabrics and flushable products.
Implementation Method 1
The solution polymerization is accomplished by free radical polymerization in a mixture of an organic solvent and water
Implementation Method 2
After the copolymerization is complete, the organic solvent is removed either via a batch or continuous process, but preferably by a continuous plate evaporator system
Data Source
AI summary
A method of making an ion triggerable cationic polymer by solution copolymerizing one or more vinyl-functional cationic monomers, one or more water insoluble or hydrophobic vinyl monomers with alkyl side chains up to 4 carbons long, and, optionally, a minor amount of one or more vinyl monomers with linear or branched alkyl groups longer than 4 carbons, alkyl hydroxy, polyoxyalkylene, or other functional groups. The solution polymerization is accomplished by free radical polymerization in a mixture of an organic solvent such as acetone and water. After polymerization is complete, the organic solvent is preferably removed by a continuous process. The continuous process is preferably performed using a plate evaporator system.