Patent ID: 7879789

Claim:
A surfactant consisting of a compound represented by the below-described general formula (1): Y—O-(EO) l -(AO) m -(EO) n -X (1) wherein AO represents an oxyalkylene group having 3 to 4 carbon atoms; m is the average addition mole number of the oxyalkylene group and satisfies 5≦m≦100; EO represents an oxyethylene group; l and n are the average addition mole numbers of the oxyethylene groups and satisfy l=n=0; either X or Y or both are a functional group represented by —SO 3 M, —COOM, —HPO 3 M, or —(CH 2 ) q —COOM, wherein M is a hydrogen ion or a monovalent inorganic or organic cation, and q is the number of carbon atoms of the linked alkylene group and satisfies 1≦q≦4; when either X or Y is the above-described functional group, the other one can be a hydrogen atom, a methyl group, or an ethyl group; the percentage of oxyalkylene groups having 4 carbon atoms with respect to the sum of AO is 50 mass % or higher.