Fluorinated Elastomer Latex Using Specific Emulsifier for Stable Dispersion
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Solution Overview
Problem
Current methods for producing fluorinated elastomers with a glass transition point at or below room temperature are lacking, and existing emulsifiers used in fluoropolymer emulsion polymerization, such as perfluorooctanoate, result in high emulsifier content on the fluoropolymer and environmental concerns.
Innovation Solution
Development of a fluorinated elastomer latex using a specific fluorinated emulsifier with the formula C2F5O(CF2CF2O)mCF2COOA, where A is hydrogen, an alkali metal, or NH4, and m is an integer from 1 to 3, to reduce emulsifier content and improve dispersion stability, combined with emulsion polymerization of fluoromonomers like TFE, VdF, and HFP, and crosslinkable group-containing monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If perfluorooctanoate emulsifier is used for emulsion polymerization of fluoropolymer, then emulsion polymerization can be achieved, but the emulsifier attaches in large amount to the fluoropolymer and causes environmental concerns
Solution Approach 1:
The patent changes the chemical structure parameters of the emulsifier by introducing fluorinated alkyl groups with specific chain lengths (C2F5, C3F7, C4F9) and ether bonds at different positions, creating a series of fluorinated emulsifiers with varying hydrophobicity and steric hindrance. This structural parameter optimization reduces the emulsifier's affinity for the fluoropolymer surface while maintaining its emulsification performance, thereby reducing the amount attached to the final product.
Solution Approach 2:
The patent employs composite emulsifier systems where fluorinated emulsifiers work synergistically with the fluoropolymer matrix. The specific fluorinated structure (C2F5O(CF2CF2O)mCF2COOH/A) creates a compatible interface that reduces excessive adsorption while maintaining stable emulsion formation during polymerization.
2Ease of manufacture
If perfluorooctanoate emulsifier is used for emulsion polymerization, then polymerization can proceed, but environmental and sanitation properties deteriorate
Solution Approach 1:
The patent replaces the persistent perfluorooctanoate emulsifier with fluorinated emulsifiers that have optimized structures for reduced environmental persistence. The specific molecular design (with varying m values of 1-3 and different alkali metal/NH4 salts) creates emulsifiers that perform their function during polymerization and can be more easily removed or degraded, reducing long-term environmental impact.
Solution Approach 2:
By changing the counterion parameters (A = H, alkali metal, or NH4) and the ether chain length (m = 1-3), the patent optimizes the emulsifier's environmental compatibility while maintaining polymerization effectiveness. These parameter variations reduce the emulsifier's environmental persistence and toxicity compared to conventional perfluorooctanoate.
3Ease of manufacture
If conventional emulsifiers are used, then emulsion polymerization is achieved, but dispersion stability of the fluorinated elastomer is insufficient
Solution Approach 1:
The patent optimizes the emulsifier's hydrophobic tail (C2F5O(CF2CF2O)m) and hydrophilic head (CF2COOH/A) parameters to achieve optimal steric stabilization and electrostatic repulsion. The specific combination of fluorinated ether chains (m=1-3) and ionic groups creates strong adsorption on the fluoropolymer particles while providing adequate steric barrier, resulting in excellent dispersion stability in the latex formulation.
Data Source
AI summary
The current invention relates to a fluorinated elastomer latex containing an aqueous medium, a fluorinated elastomer dispersed in the aqueous medium in an amount of from 10 to 60 mass % and a fluorinated emulsifier represented by the formula (1): C2F5O(CF2CF2O)mCF2COOA (wherein A is a hydrogen atom, an alkali metal or NH4, and m is an integer of from 1 to 3), which employs no perfluorooctanoate emulsifier and which is excellent in dispersion stability of the fluorinated elastomer.