PROBLEM TO BE SOLVED: To provide a first agent composition for permanent wave stably imparting a desired shape by suppressing an over ironing to intensely damaged hair, having reduced amount of stimulating odor accompanied by a process for permanent wave and uncomfortable remaining odor on the hair, and to provide a method for treatment of the hair.SOLUTION: The first agent composition for reducing hair comprises a component (A) 1-4 wt.%, as thioglycolic acid, of thioglycolic acid or its salt, a component (B) 0.5-5 wt.% of alkanolamines and a component (C) 0.2-5 wt.% of hydroxycarboxylic acid or its salt, wherein the agent has 8.6-9.4 of pH and 0.2-1.9 of an exponent I defined in the following, I=C×[&chi÷(1+&chi)], [ In the formula, C is a content of the component (A) as the thioglycolic acid, &chi=10(pH value-9.3)]. The invention relates to the method for treating hair by using the same.COPYRIGHT: (C)2007,JPO&INPIT【課題】激しく損傷した毛髪に対しても、パーマのかかり過ぎを抑制し所望の形状を安定して賦与することができ、しかも、パーマ施術に伴う刺激臭や毛髪に残留する不快臭が少ないパーマ用第1剤組成物及び毛髪処理方法の提供。【解決手段】成分(A)~(C)(A)チオグリコール酸又はその塩:チオグリコール酸として1~4重量%(B)アルカノールアミン類:0.5~5重量%(C)ヒドロキシカルボン酸又はその塩:0.2~5重量%を含有し、pHが8.6~9.4の範囲であり、かつ「I=C×〔χ÷(1+χ)〕」〔式中、Cはチオグリコール酸としての成分(A)の含有量、χ=10^(pH値-9.3)〕で定義される指数Iが0.2~1.9の範囲である毛髪還元用第1剤組成物及びこれを用いた毛髪処理方法。【選択図】なし
