LEAK-FREE STOPPER FOR A SYRINGE ASSEMBLY HAVING LOW BREAKLOOSE AND SUSTAINING FORCES

摘要

A thermoplastic elastomer stopper that meets the desired material properties of a stopper for a syringe assembly is disclosed. The compression set of the thermoplastic elastomer stopper of the present disclosure is =50% when measured at 25% compression for 22 hrs at 70 degree C. The hardness of the thermoplastic elastomer stopper of the present disclosure is 40-70 Shore A. The viscosity of a thermoplastic elastomer stopper of the present disclosure is =70 Pa.s at 1,000 s-1 shear rate, =12.0 Pa.s at 10,000 s-1 shear rate, and = 3.0 Pa.s at 50,000 s-1 shear rate when measured using a capillary rheometer at 205 degree C (Die: Roundhole 20 mm length / 1 mm diameter / 180 degree inlet, Piston: d = 15 mm, and melting time = 7 min). The present non-lubricated stopper exhibits the required functional performance of a lubricated stopper.