STEEL CORD, RUBBER-STEEL CORD COMPOSITE, AND TIRE FOR HIGH SPEED AND HEAVY LOAD

摘要

PPROBLEM TO BE SOLVED: To provide a rubber-steel cord composite suitable as a reinforcing material for a tire for high speed and heavy load, especially usable as the tire for an airplane, and to provide a pneumatic radial tire for the high speed and heavy load, having improved durability by applying the composite as a rubber-reinforcing material. PSOLUTION: The steel cord has a multi-twisted structure obtained by twisting N (N=2 to 8) strands 2 each obtained by twisting a plurality of wires 1, satisfies the formula: εSBC/SB≥0.005 [wherein, εSBC/SBis defined by the formula: εSBC/SB=√(-b/2+√(bSP2/SP/4-c))-1 (wherein b is -1+πSP2/SP(-4RSP2/SP+dSP2/SP)/PSP2/SP; c is πSP2/SPdSP2/SPk(4πSP2/SPRSP2/SP+PSP2/SP)/PSP4/SP; R is (D-d)/2; and k is tanSP2/SP(π/2-π/N))] when d (mm) is the diameter of the strand, D (mm) is the circumcircle diameter of the cord, and P (mm) is the twisting pitch of the cord, and has an elongation at break of ≥2.5%. PCOPYRIGHT: (C)2008,JPO&INPIT