A rubber-steel cord composite in which a rubber composition and a steel cord are vulcanized and adhere to each other, wherein the rubber composition contains 1 to 10 parts by mass of a vulcanizing agent, 0.1 to 5 parts by mass of N,N-dibenzylbenzothiazole-2-sulfenamide, and 0.1 to 5 parts by mass of a bismaleimide compound, with respect to 100 parts by mass of diene rubber containing natural rubber.

A rubber-steel cord composite according to an embodiment is formed by vulcanizing and bonding a rubber composition containing 1 to 10 parts by mass of sulfur, 0.1 to 5 parts by mass of N,N-dibenzylbenzothiazole-2-sulfenamide, and 0.1 to 5 parts by mass of either one or both of hexamethylene bis-thiosulfate disodium salt dihydrate and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, with respect to 100 parts by mass of diene rubber containing natural rubber, and a steel cord. A pneumatic tire according to an embodiment includes the rubber-steel cord composite.

A rubber-steel cord composite in which a rubber composition and a steel cord are vulcanized and adhere to each other, wherein the rubber composition contains 1 to 10 parts by mass of a vulcanizing agent, 0.1 to 5 parts by mass of N,N-dibenzylbenzothiazole-2-sulfenamide, a melamine derivative, and a resorcinol compound, with respect to 100 parts by mass of diene rubber containing natural rubber.

Provided are: an elastomer-metal cord composite which can improve various performance of a tire, such as steering stability, corrosion propagation resistance, and belt layer separation resistance; and a tire including the same. In an elastomer-metal cord composite (10), a metal cord (2) composed of a bundle of plural metal filaments (1) that are arranged in a single row without being twisted together is coated with an elastomer (3). A gap is provided between adjacent metal filaments, and when the diameter of the metal filaments is defined as D (mm), a gap amount, which is a distance between the surfaces of the adjacent metal filaments that is measured in a direction orthogonal to an extending direction of the metal cord, is defined as G (mm), and the number of metal filaments constituting the metal cord is defined as N (filaments), the elastomer-metal cord composite (10) satisfies a relationship expressed by the following Formula (1): 0.45≤[(D/2).sup.2×π×N]/{D×[D×N+G×(N−1)]}≤0.77 (1) wherein, D and G>0, and N is an integer.

Provided is an elastomer reinforcement cord with improved rust resistance. An elastomer reinforcement cord 10 includes metal filaments and a polymer material. The elastomer reinforcement cord 10 has a multi-strand structure which includes: at least one core strand 21 formed by twisting plural metal filaments 1a and 1b together; and two or more sheath strands 22 each formed by twisting plural metal filaments 11a and 11b together, the sheath strands being twisted together around the core strand. An intra-sheath-strand filling rate a, which is a ratio of the area of the polymer material with respect to an intra-sheath-strand gap region A, is 52% or higher, and an inter-strand filling rate b, which is a ratio of the area of the polymer material with respect to an inter-strand gap region B, is 75% or higher.

In a pneumatic tire according to an embodiment, a belt layer is configured such that the angle of a belt cord relative to the tire circumferential direction is more than 30° and 40° or less. An organic fiber cord of a belt-reinforcing layer, which is placed on the radially outer side of the belt layer, is configured such that when the number of twists per 10 cm length is T (twists/10 cm), the fineness is D (dtex), and the fiber density is ρ (g/cm.sup.3), the twist coefficient K defined as T×(D/ρ).sup.1/2 is 900 to 2,600, and the product of the load at 5% elongation LASE 5% (N) of the organic fiber cord and the end count E (cords/25 mm) of the organic fiber cord is 1,000 N or more.

A metal or metallized reinforcer, at least the surface of which is at least partially metallic, comprises at least a metallic part coated with a polybenzoxazine, the repeat units of which comprise at least one unit corresponding to the formulae (I) or (II): ##STR00001##
in which Z.sub.1 and Z.sub.2, which are identical or different, represent an at least divalent, aliphatic, cycloaliphatic or aromatic bonding group comprising at least one carbon atom and optionally at least one heteroatom selected from O, S, N and P. Such a reinforcement can be used for the reinforcement of a rubber article, in particular a motor vehicle tire.

A two-layer multi-strand cord (60) comprises an internal layer (CI) of the cord made up of J>1 internal strands (TI) and an external layer (CE) of the cord made up of L>1 external strands (TE). The cord satisfies the relationship 95≤MC≤175, where MC=(J×MI+L×ME)/(J+L); MI=200×cos.sup.4(α)×[Q×(D1/2).sup.2×cos.sup.4(β)+P×(D2/2).sup.2×cos.sup.4(δ)+N×(D3/2).sup.2×cos.sup.4(γ)]/[Q×(D1/2).sup.2+P×(D2/2).sup.2+N×(D3/2).sup.2]; and ME=200×cos.sup.4(α′)×[Q′×(D1′/2).sup.2×cos.sup.4(β′)+N′×(D2′/2).sup.2×cos.sup.4(γ′)]/[Q′×(D1′/2).sup.2+N′×(D2′/2).sup.2], where D1, D1′, D2, D2′, and D3 are in mm, α and α′ are the helix angle of each internal and external strand (TI), β and β′ are the helix angle of each internal thread (F1, F1′), δ is the helix angle of each intermediate thread (F2) and γ and γ′ are the helix angle of each external thread (F3, F2′).

A pneumatic radial tire is provided that includes belt layers disposed on an outer circumferential side of a carcass layer in a tread portion, and a belt cover layer disposed on an outer circumferential side of the belt layers, the belt cover layer including organic fiber cords helically wound along a tire circumferential direction, the belt layers including steel cords arranged at an incline with respect to the tire circumferential direction in such a manner as to intersect one another between the layers, each of the belt layers having a bending rigidity of 16500 N.Math.mm.sup.2/.sub.50 mm or less per 50 mm width in a direction orthogonal to a longitudinal direction of the steel cords, and the belt cover layer including organic fiber cords having an elongation of 2.0% to 4.0% under a load of 2.0 cN/dtex, the organic fiber cords being helically wound along the tire circumferential direction.

The steel wire for the steel cord of the present invention includes a plating layer of Cu-M-Zn (M is one or two elements of Co, Ni, Cr, Mo, Al, In, or Sn) and has a concentration gradient in which the M content ratio in a region from the surface to ¼ of the plating layer is 40% or more compared with the M content ratio in the entire region of the plating layer, and the steel cord for rubber reinforcement is obtained by a manufacturing method comprising: performing sequential plating on a surface of a steel wire in the order of Cu.fwdarw.M.fwdarw.Zn; performing a primary diffusion, for concentration gradient of M, by subjecting the sequentially plated steel wire to high-frequency induction heating using 1-500 MHz; and performing a secondary diffusion, following the primary diffusion, by medium-frequency induction heating using 10-500 KHz.