Piston member for syringe

Abstract

[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.

Dependencies are inferred from the claim text.