| 摘要 |
PROBLEM TO BE SOLVED: To prevent the corrosion of the metal part or the electrolytic corrosion due to the contact with different type metal by falling the pH value of direct liquid type ink in a specific range, and combining the spring of the metal component in contact with the metallic holder with the metal surface with the difference of the oxidation-reduction potential of the surface of the spring being a specific value or less. SOLUTION: The sealing surface of a circumferential state substantially coincident with the shape of a ball 1 is formed on the inner surface of a seal caulked part 2a to be sealed from the atmosphere even by the pressing force of a weak spring 3. Ink is adjusted to 3 to 9 of pH by pH adjustor. Further, the spring 3 of the metal component in contact with the metal holder 3 loosely engaged with the ball 1 is combined with the surface of the metal having 0.5V or less of the difference of oxidation-reduction potential (EO) of the surface of the spring 3. Thus, the corrosion of the metal part or the electrolytic corrosion due to the contact with different type metal can be prevented. |
