Water/oil repellent composition, method for its production, and article

A method for producing a water/oil repellent composition, which comprises polymerizing monomer components comprising the following monomer (a), the following monomer (b) and the following monomer (c) in a liquid medium in the presence of a surfactant and a polymerization initiator, to form a copolymer:

• monomer (a):
• a compound represented by the following formula (1):
• (Z−Y)nX (1)
• wherein Z is a C4-6 perfluoroalkyl group, Y is a C1-4 alkylene group, n is 1, and X is at least one group represented by the following formula (3-3)
• —OC(O)CR═CH2 (3-3),
• wherein R is a hydrogen atom, a methyl group or a chlorine atom,
• monomer (b):
• a (meth)acrylate having no polyfluoroalkyl group and having an alkyl group with 20 to 24 carbon atoms,
• monomer (c):
• a compound represented by the following formula (5),
• CH2═CR1C(O)O−[(C2H4O)a(C4H8O)b]—H (5),
• wherein R1 is a hydrogen atom or a methyl group, a is 10, b is 5, and a bonding order of (C2H4O) units and (C4H8O) units is not limited,
• wherein a content of C2H4O (EO) units is from 0.05 mass % to 9.93 mass %, relative to the total mass content of units based on all monomers in the copolymer, and
• wherein a content of units based on the monomer (a) is from 5 to 40 mass %, a content of units based on the monomer (b) is from 40 to 94.9 mass %, and a content of units based on the monomer (c) is from 0.1 to 20 mass %, relative to the total mass content of units based on all monomers in the copolymer.