Sumitomo Rubber Industries Limited

Yuichiro Matsutani

Eiji Yao

Naoyuki Ishida

An object of the present invention is to provide a medical rubber composition having excellent non-elution characteristic and gas permeability. The present invention provides a medical rubber composition containing: (a) a butyl rubber, (b) a diene-based rubber containing polybutadiene, (c) a peroxide-based crosslinking agent, and (d) a co-crosslinking agent, wherein an amount of (b) the diene-based rubber in 100 parts by mass of the rubber component composed of (a) the butyl rubber and (b) the diene-based rubber is 15 parts by mass or more and 90 parts by mass or less, and a mass ratio ((d)/(c)) of (d) the co-crosslinking agent to (c) the peroxide-based crosslinking agent is 1.2 or more and 25 or less.

Medical rubber composition, medical rubber component, and prefilled syringe

A gasket having a novel structure ensuring both the gas tightness and the low-friction slidability is provided. A sliding portion of the gasket () includes at least a first annular projection (A), an annular recess and a second annular projection (B) arranged in this order in a direction rearward from a distal portion of the gasket serving as a liquid contact portion. The first projection (A) is designed so that a first peak appears adjacent the distal portion of the gasket when the gasket is fitted in the syringe barrel () and a product &#x3b1; of a contact pressure Pand a width Dof the first peak is 0.4&#x2266;&#x3b1;&#x2266;1.0 as determined by an FEM analysis.

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Kobe, Japan

Yuichiro Matsutani