| 摘要 |
[Objective]: To provide a low-cost piston member for syringes, with sufficiently satisfying slidability and sealing performance such as non-leakage and vapor impermeability, without size limitation, from small to large diameters.;[Solution]: A piston member 10, such as a gasket 10a or a middle piston 10b, is formed by cut-processing a PTFE block and is press-fitted in a syringe barrel 1 to be slidably used. Protruded rims 13 are formed at least in a circumferential direction of perimeter of a slide-contact surface 11a adjacent to a liquid contact surface 14 of a drug solution 30, in a slide-contact surface 11 of the piston member 10, slidingly making contact with an inner circumferential surface 2 of the syringe barrel 1. After cut-processing, pitch P of the protruded rims 13 is 50 μm or smaller, and press-fit margin T to the syringe barrel 1 is 10 to 150 μm. |
| 主权项 |
1. A piston member formed by cut-processing a PTFE block and pressed and fitted in a syringe barrel to be used in a slidable manner,
the piston member comprising protruded rims formed at least in a circumferential direction of a whole circumference of a slide-contact surface that is adjacent to a liquid contact surface in contact with a drug solution, and that is a part of a slide-contact surface of the piston member, slidingly making contact with an inner circumferential surface of the syringe barrel, wherein after the cut-processing, a pitch of the protruded rims is not larger than 50 J..lm, and a press-fit margin of the piston member with respect to the syringe barrel is 10 to 150 J.llll. |
