Surfactant comprising fluorine-containing polymer

A liquid modifier, which is a liquid modifier for paint, a liquid modifier for ink or a liquid modifier for photographic emulsion, wherein the liquid modifier comprises a surface active agent comprising a fluorine-containing copolymer comprising repeating units derived from the following monomers (a), (b) and (c):

• (a) a fluorine-containing monomer having a fluoroalkyl group, represented by the general formula:
• CH2═C(—X)—C(═O)—Y—Z—Rf (1)
• wherein X is a hydrogen atom;
• Y is —O—;
• Z is a C1 to C10 aliphatic group, a C6 to C10 aromatic or cyclic aliphatic group, a —CH2CH(OZ1) CH2— group wherein Z1 is a hydrogen atom or an acetyl group, a —(CH2)m—SO2—(CH2)n— group or a —(CH2)m—S—(CH2)n— group wherein m is an integer from 1 to 10 and n is an integer from 0 to 10, and
• Rf is a linear or branched C1 to C7 fluoroalkyl group,
• (b) a hydrophilic monomer which is polyalkyleneglycol (meth)acrylate represented by the general formulas:
• CH2═CX1C(═O)—O—(RO)n—X2 (2a)
• and
• CH2═CX1C(═O)—O—(RO)n—C(═O)CX1═CH2 (2b)
• wherein X1 is a hydrogen atom or a methyl group,
• X2 is a hydrogen atom or a saturated or unsaturated C1-C22 hydrocarbon group,
• R is a C2-C6 alkylene group, and
• n is an integer from 1 to 90, and
• (c) a monomer having an ion-donating group, which is a compound having a cation-donating group that is tertiary or quaternary amino group, and a carbon-carbon double bond,
• wherein the content of the monomer (a) is 45-85 wt %, the content of the monomer (b) is 8-50 wt % and the content of the monomer (c) is 0.5-20 Wt % based on the fluorine-containing copolymer.