LIP-SHAPED SEAL MEMBER, AND HYDRAULIC MASTER CYLINDER FOR VEHICLE USING LIP-SHAPED SEAL MEMBER

摘要

PROBLEM TO BE SOLVED: To provide a lip-shaped seal member capable of reducing environmental load and having flexibility and strength, and a hydraulic master cylinder for a vehicle using the lip-shaped seal member.SOLUTION: A lip-shaped seal member 82a has a base portion 821, and a lip portion 822 endlessly projecting from the base portion 821, and the lip-shaped seal member 82a liquid-tightly and slidably presses the lip portion 822 to a sealed face. The lip-shaped seal member 82a is composed of a rubber composition including 0.1-60 pts.mass of at least one of oxidized cellulose fiber and cellulose nanofiber to 100 pts.mass of rubber, and carbon black. An average value of a fiber diameter of the oxidized cellulose fiber is 10 μm-30 μm, and an average value of a fiber diameter of cellulose nanofiber is 1 nm-200 nm.SELECTED DRAWING: Figure 2