Patent ID: 8056903

Claim:
A rod sealing system, which comprises a buffer ring, a rod seal, and a dust seal, provided successively in this order from a hydraulic fluid side toward an outside in an annular clearance between two members that are in relative reciprocating motion to one another, the buffer ring comprising a thermoplastic polyurethane molding product obtained by subjecting a thermoplastic polyurethane molding product prepared by reaction of (A) a high molecular weight polycarbonatediol having a number average molecular weight Mn of 500-6,000, (B) an aromatic diisocyanate, and (C) a low molecular weight diol as a chain elongation agent in an NCO/OR ratio of 0.95-1.20 to heat treatment under conditions that a glass transition point (Tg) of hard phases becomes 170Â° C. or higher, and an endothermic peak area (Î”H) at Tg becomes 5 J/g or more, by differential scanning calorimetry.