| CPC C08F 16/26 (2013.01) [B01D 61/145 (2013.01); B01D 61/243 (2013.01); B01D 69/02 (2013.01); C02F 1/444 (2013.01); C07C 43/17 (2013.01); B01D 2325/34 (2013.01)] | 15 Claims |
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1. A method for producing a composition, the method comprising a step A of performing ultrafiltration, microfiltration, dialysis membrane treatment, or a combination thereof on a composition comprising water and a water-soluble fluoropolymer, wherein the fluoropolymer is a polymer comprising a structural unit M3 derived from a monomer represented by general formula (1):
CX2═CY(—CZ2—O—Rf-A) (1)
wherein
X is the same or different and is —H or —F;
Y is —H, —F, an alkyl group, or a fluorine-containing alkyl group;
Z is the same or different and is —H, —F, an alkyl group, or a fluoroalkyl group;
Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond; and
A is —COOM, —SO3M, —OSO3M, or —C(CF3)2OM, wherein M is —H, a metal atom, —NR74, imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent, and R7 is H or an organic group;
provided that at least one of X, Y, and Z comprises a fluorine atom,
wherein a content of the structural unit M3 in the fluoropolymer is 60 mol % or more based on all polymerization units.
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