| 摘要 |
PROBLEM TO BE SOLVED: To improve lightweight, high-speed durability, and low-noise property of a pneumatic radial tire. SOLUTION: A composite cord of a belt cover layer 7 provided so as to cover a part or whole of a belt layer 6 of the pneumatic radial tire is composed of a low modulus of elasticity fiber bundle and a high modulus of elasticity fiber bundle, all of the fibers of the low modulus of elasticity fiber bundle and the high modulus of elasticity fiber bundle are twisted in the same direction, the twist coefficient KH of the high modulus of elasticity fiber bundle is made lower than the twist coefficient KL of the low modulus of elasticity fiber bundle, and the ratio of these twist coefficients KH/KL is made within the range of 0.2-0.8. When the number of twists of the high modulus of elasticity fiber bundle is defined as TH, the number of twists of the low modulus of elasticity fiber bundle as TL, thickness of the high modulus of elasticity fiber bundle as DH, thickness of the low modulus of elasticity fiber bundle as DL, the specific gravity of the high modulus of elasticity fiber bundle asρH, and the specific gravity of the low modulus of elasticity fiber bundle asρL, respectively, KH=TH√(DH/ρH) and KL=TL√(DL/ρL) are satisfied. COPYRIGHT: (C)2010,JPO&INPIT |
