| 摘要 |
PURPOSE:To obtain a gasket, with high reliability, which is securely operated under lower pressure without making thickness of the thin face part extremely thin by making a molecular orientation of polymer on the surrounding part of a breaking groove formed in the sealed gasket, approximately in parallel to the groove. CONSTITUTION:The sealed gasket 20 for explosion-proof alkaline cell is an injection molding product of polypropylene or the like, integratedly formed of the boss part 22, inner cylindrical part 24, corn-shaped slant face part 26, and outer cylindrical part 28. When the gas pressure inside the cell becomes abnormally high, the gasket inner cylindrical part 24 is broken with a longitudinal groove 24a along the axial direction serving as a starting point. In this sealed gasket 20, the molecular orientation of polymer on the surrounding part of the longitudinal groove 24a is in parallel to the longitudinal 24a. For this reason, this part is inclined to be cracked along the longitudinal groove 24a, so the residual thickness of the longitudinal groove 24a need not be made extremely thin. Therefore, the control of dimension during molding is performed more easily, and the dispersion of operating pressure, caused by molding error and temperature, can be reduced. Polypropylene, on account of being strong in molecular orientation, is suitable for composing the sealed gasket. |
