PROBLEM TO BE SOLVED: To provide hair treatment compositions, particularly hair dyeing pretreatment compositions, which have better substantivity and fastness than the prior art and can maintain a good texture even under a humid atmosphere.SOLUTION: A hair treatment composition contains a water soluble amphoteric copolymer obtained by copolymerization of a cationic monomer (A) represented by the general formula (1) in the figure, an acrylamide (B), and an anionic monomer (C). The copolymer has a weight average molecular weight of 2,000-5,000, and a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), namely, Mw/Mn, of 15 or less.COPYRIGHT: (C)2015,JPO&INPIT【課題】染色性及び堅牢性が従来品よりも優良でかつ、湿度の高い雰囲気下においても良好な感触が維持可能な毛髪処理用組成物、特に染毛前処理用組成物の提供。【解決手段】下記一般式(1)で表されるカチオン性モノマー(A)、アクリルアミド類(B)、およびアニオン性モノマー(C)を共重合することで得られる重量平均分子量が2,000~5,000であり、かつ、重量平均分子量(Mw)と数平均分子量(Mn)の比(Mw/Mn)が15以下である水溶性両性共重合体を含む毛髪処理用組成物。【選択図】なし
