Examples of such surfactants include an aliphatic amine salt represented by the formula: ##STR8## (wherein, R1 is an alkyl group having 8 to 18 carbon atoms, R2 and R3 are a hydrogen atom or alkyl group having 1 to 18 carbon atoms, X is an organic acid such as acetic acid and methylsulfuric acid or an inorganic acid such as hydrochloric acid and sulfuric acid),