Patent ID: 7776982

Claim:
A surface treatment agent comprising a fluoropolymer which has repeating units derived from a fluorine-containing monomer of the formula: wherein X is a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a CFX 1 X 2 group (in which X 1 and X 2 are each a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group; Y is an aliphatic group having 1 to 10 carbon atoms, an aromatic or cycloaliphatic group having 6 to 10 carbon atoms, a —CH 2 CH 2 N(R 1 )SO 2 — group (in which R 1 is an alkyl group having 1 to 4 carbon atoms) or a —CH 2 CH(OY 1 )CH 2 — group (in which Y 1 is a hydrogen atom or an acetyl group); and Rf is a linear or branched perfluoroalkyl or perfluoroalkenyl group having 1 to 6 carbon atoms, or a fluoroether group having totally 1 to 200 repeating units selected from the group consisting of the repeating units: —C 3 F 6 O—, —C 2 F 4 O— and —CF 2 O—, and wherein the fluoropolymer contains a silicon atom, and the silicon-containing fluoropolymer comprises repeating units derived from the fluorine-containing monomer of formula (I) and repeating units derived from a silicon-containing monomer represented by formula (II): wherein A is a monovalent group having at least one silicon atom represented by the formula: Rsi-X— wherein Rsi is R 11 —(Si(R 12 ) 2 —O) p — (in which the R 11 group is a hydrogen atom, or a C 1 -C 8 alkyl group or a C 6 -C 8 aryl group; each of the R 12 groups is the same or different, and is a hydrogen atom, a C 1 -C 8 hydrocarbon or halogenated hydrocarbon group optionally having a functional group; and p is a number of 1 to 100); and X is a direct bond, —(CH 2 ) q — (in which q is a number of 1 to 20), —(CH 2 ) 2 —O— (in which r is a number of 0 to 20), or —(CH 2 ) s —OC(═O)— (in which s is a number of 0 to 20); and R 1 is a hydrogen atom or a methyl group.