Mold release agent for tire bladder, tire bladder, and pneumatic tire

A mold release agent is coated onto a tire bladder made of a zinc-oxide-incorporated butyl rubber during pneumatic-tire molding, the mold release agent is characterized by containing (A) organopolysiloxane, which contains a carboxy group indicated by the general formula (1) below (in the formula, R1 is a substituted or unsubstituted C1-C30 monovalent hydrocarbon group excluding R2, R2 is a carboxy-group-substituted C1-C30 monovalent organic group, R3 is R1 or R2, and n is an integer 3 to 2000.). This mold release agent produces a longer service life of a tire bladder and leads to reduced tire production cost because the amount of silicone that migrates to the tire side is low when the tire is released, and the repeated mold-release performance is enhanced. 轮胎胶囊用脱模剂，其为在空气轮胎成型时涂布于配合有氧化锌的丁基橡胶制轮胎胶囊的脱模剂，其特征在于，含有：(A)由下述通式(1)(式中，R为R以外的未取代或取代的碳原子数1～30的1价烃基，R为用羧基取代的碳原子数1～30的1价有机基团，R为R或R，n为3～2,000的整数。)表示的含有羧基的有机聚硅氧烷。就本发明的轮胎胶囊用脱模剂而言，使轮胎脱离时的向轮胎侧的有机硅的迁移量少，反复脱模性能提高，因此轮胎胶囊的寿命延长，导致轮胎的生产成本的降低。