Oleophobic Fluoropolymer Emulsion via Ultrasonic Pre-Emulsification
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Solution Overview
Problem
Existing methods for preparing fluoropolymer emulsions face challenges in fully emulsifying fluorinated monomers with non-fluorinated surfactants, leading to unstable polymer products with low fluorine content and poor hydrophobic and oleophobic modification abilities, while fluorine-containing surfactants are environmentally persistent.
Innovation Solution
A process involving ultrasonic pre-emulsification of fluorinated and non-fluorinated monomers with controlled intensity and time, followed by free-radical polymerization, allows for high fluorine content and stability in the resulting fluoropolymer emulsion, using low levels of non-fluorinated surfactants and avoiding fluorine-containing surfactants to minimize environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorine-containing surfactants are used to emulsify fluorinated monomers, then emulsification effectiveness is improved, but environmental persistence and bioaccumulation risks increase
Solution Approach 1:
The patent uses non-fluorinated surfactants as intermediary substances to emulsify fluorinated monomers, avoiding direct use of fluorine-containing surfactants. The non-fluorinated surfactant acts as a mediator that enables emulsification without introducing environmentally persistent fluorinated surfactant residues into the system.
Solution Approach 2:
The patent extracts the fluorine atoms from the surfactant component while retaining the emulsification function. By separating the surfactant function from fluorine content, the system achieves effective emulsification without the harmful environmental effects associated with fluorine-containing surfactants.
2Object-affected harmful factors
If non-fluorinated surfactants are used to emulsify fluorinated monomers, then environmental safety is improved, but emulsification effectiveness and polymer stability deteriorate
Solution Approach 1:
The patent optimizes parameters including surfactant concentration, monomer ratio, pH value, and temperature to achieve effective emulsification with non-fluorinated surfactants. By carefully adjusting these parameters, the system overcomes the inherent difficulty of emulsifying fluorinated monomers with non-fluorinated surfactants while maintaining polymer stability.
Solution Approach 2:
The patent employs composite emulsion systems combining non-fluorinated surfactants with specific non-fluorinated monomers (such as acrylic acid, methacrylic acid, or itaconic acid) to create a synergistic effect that enhances both emulsification effectiveness and polymer stability while avoiding fluorinated surfactants.
3Quantity of substance
If high concentrations of surfactant are used to emulsify fluorinated monomers, then emulsification completeness is improved, but product stability and fluorine content decrease
Solution Approach 1:
The patent uses moderate concentrations of non-fluorinated surfactants combined with optimized monomer ratios and ultrasonic pre-emulsification to achieve complete emulsification without the need for excessive surfactant concentrations. This approach prevents surfactant-induced instability while ensuring complete emulsification of fluorinated monomers.
Solution Approach 2:
The patent implements ultrasonic pre-emulsification as a preliminary step before the main polymerization process. This pre-emulsification creates a stable precursor emulsion that facilitates complete and uniform distribution of fluorinated monomers, eliminating the need for high surfactant concentrations during the polymerization stage.
4Loss of substance
If fluorinated monomers are not completely emulsified, then surfactant concentration is reduced, but polymer product stability and fluorine content deteriorate
Solution Approach 1:
The patent performs ultrasonic pre-emulsification as a preliminary step that completely emulsifies fluorinated monomers before polymerization. This preliminary action ensures complete monomer dispersion, allowing the use of low surfactant concentrations during polymerization while maintaining high polymer stability and fluorine content.
Solution Approach 2:
The patent optimizes multiple parameters including pH value, temperature, surfactant-to-monomer ratio, and ultrasonic treatment conditions to achieve complete emulsification efficiency at low surfactant concentrations. These parameter optimizations ensure that fluorinated monomers are completely emulsified without requiring excessive surfactant that would compromise product stability.
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 process achieves excellent hydrophobic and oleophobic modification of fibers and nonwoven materials, with treated materials showing high fluorine content, stability, and excellent oleophobicity without significant air flux loss, making them suitable for filter applications.
Implementation Method 1
the mixture is subjected to ultrasonic vibration at an intensity and for a period of time sufficient to form a pre-emulsion
Implementation Method 2
combining components comprising: a fluorine-containing monoethylenically-unsaturated monomer, a fluorine-free monoethylenically-unsaturated monomer, and a surfactant... thereby providing a mixture
Implementation Method 3
the mixture is subjected to free-radical polymerization conditions and allowed to polymerize
Data Source
AI summary
The disclosure provides a process for preparing an oleophobic fluoropolymer emulsion. The resulting fluoropolymer emulsion has excellent hydrophobic and oleophobic modification ability (as coatings) on polyester fibers such as polyester (PET), polypropylene (PP) and woven and nonwoven fabrics. Accordingly, the woven and nonwoven materials so coated are useful in venting filter applications.