PROBLEM TO BE SOLVED: To provide a composition for keratin fibers, such as hair, which includes a volatile ingredient that can be a new substitute for volatile silicone, and can provide the keratin fibers with improved smoothness and improved volume reduction effects compared with a composition including a conventional substitute, such as isododecane and isohexadecane, for volatile silicone.SOLUTION: The present invention relates to a composition for treating keratin fibers, preferably hair, comprising: (a) at least one volatile branched C13-15 alkane oil； (b) at least one optional additional volatile oil other than the (a) branched C13-15 alkane oil； and (c) at least one non-volatile oil； where the amount of the (a) volatile branched C13-15 alkane oil is 30 mass% or more, preferably 40 mass% or more, further preferably 50 mass% or more, relative to the total mass of the (a) branched C13-15 alkane oil and the (b) optional additional volatile oil. The volatile branched C13-15 alkane oil can be used as a new substitute for volatile silicone. The composition according to the present invention can provide keratin fibers with smoothness and volume reduction effects which are better than those provided by a composition including a conventional substitute, such as isododecane and isohexadecane, for volatile silicone, instead of the volatile branched C13-15 alkane oil in the composition according to the present invention.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】揮発性シリコーンの新しい代替物となりうる揮発性成分を含み、且つイソドデカン及びイソヘキサデカン等の、揮発性シリコーンの従来の代替物を含む組成物と比べて良好な滑らかさ効果及び改善されたボリュームダウン効果をケラチン繊維に付与することができる、毛髪等のケラチン繊維のための組成物を提供すること。【解決手段】本発明は、(a)少なくとも1種の揮発性分枝状C13～15アルカン油と、(b)任意選択の、(a)分枝状C13～15アルカン油以外の少なくとも1種の追加の揮発性油と、(c)少なくとも1種の不揮発性油とを含み、(a)揮発性分枝状C13～15アルカン油の量が、(a)分枝状C13～15アルカン油と(b)任意選択の追加の揮発性油との総質量に対して、30質量%以上、好ましくは40質量%以上、より好ましくは50質量%以上である、ケラチン繊維、好ましくは毛髪を処置するための組成物に関する。揮発性分枝状C13～15アルカン油は、揮発性シリコーンの新しい代替物として使用することができる。本発明による組成物は、本発明による組成物中の揮発性分枝状C13～15アルカン油の代わりに揮発性シリコーンの従来の代替物、例えばイソドデカン及
