Abstract: Rubber reinforcing polyester filament cord having flexibility, adhesiveness to halogenated butyl rubber and EPDM rubber, and smoothness; comprising a polyester filament yarn with a surface coating of an aromatic polyepoxide, initial condensation product of resorcin-formaldehyde (A) and a rubber latex (B), single-twisted at 3-150 turns per meter to make a twisted cord and satisfying properties (a) to (c): (a) about 0.15 to 0.35 coefficient of dynamic friction between filament cord and smooth metal, (b) about 0.05 or less variation of coefficient of dynamic friction between filament cord and smooth metal, and (c) about 3 wt % or more rubber remaining after standard cord stripping test.

Abstract: Adhesive composition for adhering rubber and fiber which make synthetic fibers highly adhesive to rubber even when a reduced amount of the composition is applied to the fibers; rubber-reinforcing synthetic fibers coated with the adhesive composition to have improved adhesiveness to rubber while retaining the intrinsic characteristics of the synthetic fibers themselves; and fiber-reinforced rubber structures where the rubber has been reinforced by the rubber-reinforcing synthetic fibers. The adhesive composition contains, adhesive matrix and a silicate compound, the silicate compound comprising silicon and magnesium at a ratio by weight of silicon/magnesium of from 1/0.1 to 1/1.0. Preferably, a 1% aqueous dispersion of the silicate compound has a transmittance of about 50% or more and/or a 2% aqueous dispersion of the silicate compound has a thixotropy index of from about 2.0 to 10.0. The silicate compound is preferably a smectite.