PROBLEM TO BE SOLVED: To provide a rubber plug for a vial in which a plate-shape discoid cap portion and a leg portion are solidly bonded to each other by a two-step molding method.SOLUTION: The rubber plug 1 for vial has a bonding surface between a leg portion 1B and a discoid cap portion 1A, the bonding surface is formed as a concentric concavo-convex surface having a boss portion 1F, a ring-like groove 1G having a larger diameter, and a ring-like groove 1H having a smaller diameter. Since the base end side of the leg portion 1B including the bonding surface is formed of a butyl rubber of the same material as the discoid cap portion 1A, the discoid cap portion 1A is solidly bonded to the base end side of the leg portion 1B when the discoid cap portion 1A is press molded integrally with the base end side portion of the leg portion 1B by a two-step molding method Therefore, the rubber plug 1 for a vial is suitable to be a rubber plug for a vial which stores liquid medicinal chemicals by freezing preservation.COPYRIGHT: (C)2013,JPO&INPIT【課題】円板状笠部と脚部とが2段成形法により強固に接合されたバイアル用ゴム栓を提供する。【解決手段】バイアル用ゴム栓1は、脚部1Bと円板状笠部1Aとの接合面がボス部1F、大径のリング状溝1G、小径のリング状溝1Hを有する同心円状の凹凸面とされており、しかも、その接合面を含む脚部1Bの基端部側が円板状笠部1Aと同じ材質のブチル系ゴムで構成されているため、2段成形法により脚部1Bの基端部側に円板状笠部1Aが一体にプレス成形される際、その脚部1Bの基端部側に円板状笠部1Aが強固に接合される。従って、バイアル用ゴム栓1は、液体医薬品などを凍結保存するバイアル用のゴム栓として好適である。【選択図】図3
