| 摘要 |
PROBLEM TO BE SOLVED: To suppress a leakage of an ink without reducing a viscous fluid layer and to hold an ordinary pressure in an ink tank, by arranging the layer having a specified contact angle with a wall member and a specified surface tension in an air flow passage, and temporarily forming an air flow passage in the fluid layer in association with a reduction in a pressure in the tank. SOLUTION: A connecting portion 1b of a central post 1a to an inner wall is formed in the rear side of a barrel 1, and a sector space 7 is formed. The space 7 forms an air flow passage communicating with the atmosphere through an ink tank 1c, and the tank 1c is normally closed by a viscous fluid layer 8 to be partitioned from the atmosphere. The layer 8 is formed of, for example, a gelatinized material containing an α-olefin and a polybutene as main agents. In this case, a contact angle θ with a member for forming an inner wall of the space 7 is set to 0<θ<90 degrees and a surface tension α is set to 10 dyn/cm<=α<=73 dyn/cm (20 deg.C). Thus, the air flow passage is formed in the layer 8 only when needed to allow the air to flow. |
