Fluoropolymer Dispersion Concentration With Low Emulsifier Residue

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Solution Overview

Problem

Existing methods for producing fluoropolymer aqueous dispersions struggle to efficiently remove fluorine-containing emulsifiers, leading to high residual surfactant levels in the dispersion, which can affect the physical properties of moldings and stability of the dispersion.

Innovation Solution

A method involving polymerization in an aqueous medium with a fluorine-containing surfactant having an octanol/water partition coefficient of 1.5 to 3.5, followed by a concentration treatment using phase separation or electric concentration, effectively reduces the surfactant concentration to below 5% by mass and achieves high solid matter concentrations of 30-80% in the fluoropolymer dispersion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a fluorine-containing emulsifier is used during polymerization to maintain dispersion stability, then the dispersion stability of fluoropolymer particles is improved, but the fluorine-containing emulsifier concentration in the final dispersion increases, which deteriorates the physical properties of moldings

Engineering Contradiction:
Improvedispersion stabilityVSAvoidfluorine-containing emulsifier concentration
Core Design Contradiction:
Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The patent applies extraction by adding a nonionic surfactant to the aqueous dispersion after polymerization, which then contacts with an anion exchange resin to remove the fluorine-containing emulsifier from the dispersion, thereby reducing emulsifier concentration while maintaining dispersion stability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a nonionic surfactant as an intermediary substance that facilitates the removal of fluorine-containing emulsifier through contact with anion exchange resin, enabling efficient separation without directly affecting the fluoropolymer particles

Inventive Principle:
Principle #24Intermediary (Mediator)

2Quantity of substance

If a nonionic surfactant is added to the aqueous dispersion after polymerization to remove the fluorine-containing emulsifier, then the fluorine-containing emulsifier concentration is reduced, but the nonionic surfactant added mostly remains in the dispersion

Engineering Contradiction:
Improvefluorine-containing emulsifier concentrationVSAvoidnonionic surfactant residue
Core Design Contradiction:
Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potential harm of nonionic surfactant residue into a benefit by carefully selecting surfactants with complementary properties that work synergistically with the anion exchange resin to remove fluorine-containing emulsifier while minimizing unwanted residues in the final dispersion

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Quantity of substance

If electric concentration is used to concentrate the fluoropolymer aqueous dispersion, then the solid matter concentration is increased, but the nonionic surfactant added before concentration mostly remains in the dispersion

Engineering Contradiction:
Improvesolid matter concentrationVSAvoidnonionic surfactant residue
Core Design Contradiction:
Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by adding the nonionic surfactant after the polymerization is complete and after the fluoropolymer aqueous dispersion has been obtained, rather than before concentration, to minimize surfactant residue while achieving the desired solid matter concentration through subsequent concentration processes

Inventive Principle:
Principle #10Preliminary action

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

This approach results in a fluoropolymer aqueous dispersion with low surfactant content and high solid concentration, enhancing dispersion stability and processability, and producing fluoropolymer moldings with improved thermal stability, chemical resistance, and mechanical properties.

Implementation Method 1

the fluorine-containing surfactant (A) is a fluorine-containing surfactant having an octanol/water partition coefficient of 1.5 to 3.5

Methodology Applied
Scientific EffectOctanol/water partition coefficient: Liquid-Liquid Extraction

Data Source

PatentUS20070135558A1Process for producing aqueous fluoropolymer dispersion and aqueous fluoropolymer dispersion
Publication Date: 2007.06.14 DAIKIN INDUSTRIES LTD

AI summary

The present invention provides a method of producing a fluoropolymer aqueous dispersion by which the fluorine-containing emulsifier contained in the fluoropolymer aqueous dispersion as obtained after polymerization can be efficiently removed as well as a fluoropolymer aqueous dispersion low in fluorine-containing emulsifier concentration. The present invention is a method of producing a fluoropolymer aqueous dispersion which comprises carrying out a concentration treatment comprising a concentration operation of a pretreatment fluoropolymer aqueous dispersion, wherein the pretreatment fluoropolymer aqueous dispersion is obtained by carrying out a polymerization in an aqueous medium in the presence of a fluorine-containing surfactant (A), the fluorine-containing surfactant (A) is a fluorine-containing surfactant having an octanol/water partition coefficient of 1.5 to 3.5.