PTFE Aqueous Dispersion Using Fluorinated Emulsifier
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Solution Overview
Problem
Existing PTFE emulsion polymerization methods using ammonium perfluorooctanoate (APFO) raise environmental concerns due to bioaccumulation potential, and alternative methods with non-fluorine anionic surfactants result in low concentration PTFE with poor physical properties, wettability, and mechanical stability issues.
Innovation Solution
A PTFE aqueous dispersion is developed using a fluorinated emulsifier and nonionic surfactants, specifically XCF2CF2(O)mCF2CF2OCF2COOA, with X being hydrogen or fluorine, and a polyoxyalkylene chain, to enhance wettability and mechanical stability, and the PTFE product is formulated to minimize APFO content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ammonium perfluorooctanoate (APFO) is used as an emulsifier in PTFE emulsion polymerization, then the polymerization process is effective and PTFE emulsion can be obtained, but the emulsifier has bioaccumulation potential and causes environmental harm
Solution Approach 1:
The patent removes APFO from the emulsion polymerization system and replaces it with a fluorinated emulsifier having specific molecular structure (Formula 1) that lacks bioaccumulation potential. This extraction of the harmful substance while maintaining the polymerization process resolves the contradiction between manufacturing ease and environmental harm.
Solution Approach 2:
The patent changes the chemical parameters of the emulsifier by specifying a particular fluorinated structure (Formula 1) with controlled chain length and functional groups. This parameter change maintains emulsification effectiveness while eliminating bioaccumulation, thus resolving the contradiction between process effectiveness and environmental safety.
2Object-affected harmful factors
If non-fluorine anionic surfactant is used as emulsifier, then environmental harm is reduced, but the obtained PTFE emulsion has low concentration and poor physical properties
Solution Approach 1:
The patent changes the chemical parameters of the emulsifier from non-fluorinated to fluorinated structure (Formula 1), which improves the PTFE emulsion concentration and physical properties while maintaining environmental safety. The specific fluorinated structure provides optimal balance between performance and eco-friendliness.
Solution Approach 2:
The patent uses a composite approach by combining fluorinated emulsifier with nonionic surfactant in specific proportions. This composite system achieves both high PTFE concentration and good physical properties while avoiding the environmental harm of traditional emulsifiers.
3Object-affected harmful factors
If fluorinated emulsifier other than APFO is used, then bioaccumulation is reduced, but the PTFE emulsion has poor wettability and low permeability
Solution Approach 1:
The patent optimizes the parameters of the fluorinated emulsifier (Formula 1) including chain length, functional groups, and molecular weight to achieve optimal wettability and permeability. The specific structural parameters enable the emulsion to penetrate porous substrates effectively while maintaining low bioaccumulation.
Solution Approach 2:
The patent introduces nonionic surfactant as an intermediary substance that works synergistically with the fluorinated emulsifier. This combination improves wettability and permeability of the PTFE emulsion on porous materials while the fluorinated emulsifier maintains low bioaccumulation characteristics.
4Object-affected harmful factors
If fluorinated emulsifier other than APFO is used, then bioaccumulation is reduced, but the PTFE emulsion has low mechanical stability and forms coagulates during transfer
Solution Approach 1:
The patent creates a composite emulsion system combining fluorinated emulsifier (Formula 1) with nonionic surfactant in optimized ratios. This composite system provides enhanced mechanical stability during pumping and transfer operations while maintaining the low bioaccumulation advantage of fluorinated emulsifiers.
Solution Approach 2:
The nonionic surfactant acts as a stabilizing intermediary that prevents coagulate formation during emulsion transfer. It works synergistically with the fluorinated emulsifier to maintain colloidal stability and prevent particle aggregation, thus improving mechanical stability while preserving environmental safety.
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 PTFE aqueous dispersion exhibits improved wettability and mechanical stability, and the resulting PTFE product has desirable characteristics without substantial APFO content, addressing environmental concerns and physical property limitations.
Implementation Method 1
a fluorinated emulsifier of the formula (1)... of a nonionic surfactant... excellent in wettability
Data Source
AI summary
To provide a polytetrafluoroethylene (PTFE) aqueous dispersion, which does not substantially contain ammonium perfluorooctanoate and is excellent in mechanical stability, wettability, permeability and coating property, and its product.A PTFE aqueous dispersion comprising from 15 to 70 mass % of PTFE fine particles having an average particle size of from 0.1 to 0.5 μm, from 1×10−5 to 0.5 mass %, based on the mass of the PTFE, of a fluorinated emulsifier of the formula (1): XCF2CF2(O)mCF2CF2OCF2COOA, wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4 and m is an integer of 0 or 1, and from 1 to 20 mass %, based on the mass of the PTFE, of a nonionic surfactant.