Fluorinated Copolymer Dispersion With Built-In Cationic Stability
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Solution Overview
Problem
Existing aqueous dispersions of fluorine-containing copolymers face challenges in maintaining dispersion stability due to interactions with impurities, leading to coagulation and reduced water- and oil-repellency, especially when used in fiber treatment processes.
Innovation Solution
An aqueous dispersion of a fluorine-containing copolymer is developed, comprising specific copolymerization units including a (meth)acrylate with a quaternary ammonium group, perfluoroalkyl (meth)acrylate, benzyl (meth)acrylate, a fluorine-free polymerizable monomer, and a crosslinkable group-containing monomer, with controlled ratios to enhance surface charge density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cationic emulsifier is used to give a positive potential to particle surface for stable adsorption, then adsorption stability is improved, but chemical stability deteriorates due to reaction with hydrophilic anionic impurities causing coagulation and sedimentation
Solution Approach 1:
The patent extracts the cationic charge function from the emulsifier molecule and transfers it to the polymer chain itself through copolymerization of cationic monomers. This separates the adsorption function (provided by the polymer) from the emulsification function (provided by the nonionic emulsifier), eliminating the harmful reaction with anionic impurities while maintaining stable adsorption through the permanent cationic charges on the polymer backbone.
Solution Approach 2:
The patent changes the chemical nature of the emulsifier from cationic to nonionic, and changes the source of cationic charge from external emulsifier to intrinsic polymer structure. This parameter change in molecular structure and charge origin resolves the contradiction by maintaining positive zeta potential for adsorption while eliminating reactivity with anionic substances.
2Productivity
If water- and oil-repellent particles have an overly high positive potential, then adsorption to negative fiber surface occurs rapidly, but uniform adsorption is inhibited by repulsion between particles leading to unstable performance
Solution Approach 1:
The patent creates local positive charges distributed along the polymer chain rather than concentrating charge on the particle surface. The cationic monomers are incorporated at specific positions within the copolymer structure, creating localized positive sites that provide gradual adsorption while the overall particle structure remains stable and uniformly distributable.
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 effectively improves the dispersion stability and maintains high water- and oil-repellency even at lower concentrations of charged polymerizable monomers, preventing coagulation and sedimentation, thus ensuring stable performance and processability.
Implementation Method 1
The zeta (ζ) potential of the fiber surface generally has a negative (anionic) potential... Accordingly, it is necessary that the water- and oil-repellent particles have a moderate positive (cationic) potential. Thereby, stable adsorption occurs on the fiber surface
Implementation Method 2
Appearance of water- and oil-repellency by fluorine-containing polymers is attributable to the low surface energy of fluorine atoms
Implementation Method 3
an aqueous dispersion of a fluorine-containing copolymer comprising, as copolymerization units, (A) a (meth)acrylate having a quaternary ammonium group, (B) perfluoroalkyl (meth)acrylate, (C) benzyl (meth)acrylate, (D) a fluorine-free polymerizable monomer, and (E) a crosslinkable group-containing monomer
Data Source
AI summary
An aqueous dispersion of a fluorine-containing copolymer comprising, as copolymerization units, (A) a (meth)acrylate represented by [CH2=CHRCOO(NH)rR1NR2R3R4]+Y-, (B) a perfluoroalkylalkyl (meth)acrylate represented by CmF2m+1CpH2p(NR'SO2)qOCOCR=CH2 or a polyfluoroalkylalkyl (meth)acrylate thereof, or a polyfluoroalkyl (meth)acrylate represented by CnF2n+1(CH2CF2)a(CF2CF2)b(CH2CH2)cOCOCR=CH2, (C) benzyl (meth)acrylate, (D) a fluorine-free polymerizable monomer other than components (A) and (C) , and (E) a crosslinkable group-containing polymerizable monomer. The aqueous dispersion can improve the dispersion stability of an aqueous dispersion of a water- and oil-repellent when used as a water- and oil-repellent comprising the fluorine-containing copolymer as an active component.