| abstract |
(57) Abstract: It is an object of the present invention to provide a first permanent agent having many excellent characteristics as compared with thioglycolate type permanent agents and cysteine type permanent agents. SOLUTION: A reducing agent comprising one or a combination of two or more selected from ammonium thiolactate, thiolactate monoethanolamine salt, thiolactate isopropanolamine salt, and thiolactic acid, and monoethanolamine, isopropanolamine, and ammonia. The total amount of monoethanolamine and / or isopropanolamine contained as a free and / or counter ion of thiolactic acid is thiolactic acid and / or an alkali agent consisting of one or a combination of two or more selected from water. Alternatively, the aqueous solution is adjusted to have a molar concentration ratio of 0.3 to 1.0 with respect to the total amount of thiolactate. |