Patent ID: 7351748

Claim:
A compound represented by formula (1): W—C n F 2n —X—(CH 2 CH 2 O) a —Y (1) wherein n is an integer from 2 to 6; W is a hydrogen atom or a fluorine atom; X is —COO—, —SO 2 —N(R)—, -M-O— or —CH 2 O-M-O— (wherein R is a lower alkyl group, and M is an alkylene group optionally substituted with a hydroxyl group); a is an integer from 10 to 50; and Y is a substituted or unsubstituted alkyl group having 4 to 19 carbon atoms, a substituted or unsubstituted aryl group, an alkenyl group, an alkynyl group, -M′-C m F 2m —W′ or -M′-OCH 2 —C m F 2m —W′ (wherein m is an integer from 2 to 6, W′ is a hydrogen atom or a fluorine atom, and M′ is an alkylene group optionally having one hydroxyl group), the ratio of the molecular weight (MW EO ) of the polyoxyethylene group (the moiety (CH 2 CH 2 O) a ) to the molecular weight (MW F ) of the fluoroalkyl groups (the moieties W—C n F 2n and C m F 2m —W′) being within the range expressed by the equation: MW EO /MW F =2.2 to 10 and the compound having a Griffin's HLB value of 10 to 16.