| 摘要 |
PURPOSE:To prevent corrosion at the gap in a portable timepiece by employing a rubber mixed with a given powder as a sweat insulating packing material. CONSTITUTION:The sweat insulating packing is formed by adding to a base material of natural rubber, a synthetic rubber or the like 5-20% (weight fraction) of zinc powder having a grain size of 0.0001-0.05mm. or the mixture of the zinc powder and aluminium powder. Contacting with stainless steel, the zinc powder ionizes through an anode reaction while reducing the stainless steel through a cathode reaction. Moreover, because the dissolved zinc becomes zinc hydroxide and fills gaps, the pH of sweat, sea water or the like having high chlorine concentration is kept within a given range, so that the surface of the stainless steel is maintained under a stable condition. Accordingly, corrosion at the gap between the timepiece case and the back cover or the like can be prevented. |
