PISTON ASSEMBLY FOR SYRINGE

摘要

A piston assembly (10) for a flowable materials container having a barrel (14) defining a fluid containing chamber (16). The barrel (14) is made of a body of a cyclic olefin containing polymer or a bridged polycyclic olefin containing polymer. An elastomeric piston (24) is slidably attached to the barrel (14) and provides a seal of the chamber. The piston (24) has a parylene coating on an outer surface thereof to reduce the necessary break away force. A plunger (22) is also provided and has a second mating member (42) removably connecting the plunger to a first mating member (44) of the piston. The first mating member (44) has a series of threads having a major diameter and a minor diameter, and the second mating member (42) has a series of threads having a major diameter and a minor diameter. The major and minor diameters of the second mating members (42) is appreciably smaller than the major and minor diameters of the other of the first mating member (44) to provide ease of connection.