| 摘要 |
PROBLEM TO BE SOLVED: To provide a fiber for rubber reinforcement that is excellent in adhesive property with rubber and in particular is extremely excellent in durability after dynamic fatigue, and a rubber-fiber composite material including the same.SOLUTION: The fiber cord for rubber reinforcement contains a polyester fiber, the polyester fiber comprises ethylene-2,6-naphthalate as a main repeating unit, the molecule constituting the fiber has terminal carboxyl groups in an amount of 15 equivalent/ton or more, and the amount of the terminal carboxyl groups on the fiber surface is 10 equivalent/ton or less. It is preferable that a surface treatment agent including an epoxy group is attached to the surface of the polyester fiber, that the fiber has a melting point of 275 to 310°C, and that the fiber has a strength of 7.0 to 9.8 cN/dtex. It is also preferable that the fiber has a crystal volume obtained by an X-ray wide angle diffraction of 100 to 1200 nmand has a degree of crystallinity of 30 to 60%, that the fiber has a maximum peak diffraction angle by an X-ray wide angle diffraction of 14 to 28 degrees, and that the fiber surface has an epoxy index of 1.0×10equivalent/kg or less. |
