A power transmission belt includes a transparent or semitransparent sheet material covering a portion of a surface of a belt body including a mark. At least a portion of the belt body covered with the sheet material is made of a rubber composition vulcanized with sulfur. The sheet material is made of a rubber material containing a diene rubber. The sheet material is vulcanized with sulfur together with the rubber composition forming the portion of the belt body covered with the sheet material such that the sheet material is connected to the belt body.

A raw edge V-belt includes: a compression rubber layer formed on an inner side of the belt and made of a rubber composition. The rubber composition contains a rubber component, fine cellulose fibers, and short fibers. The content of the short fibers in the rubber composition is 25 parts by mass or more and 45 parts by mass or less per 100 parts by mass of the rubber component, and the volume fraction of the short fibers in the rubber composition is 12.5 vol % or more.

A raw edge V-belt includes: a compression rubber layer formed on an inner side of the belt and made of a rubber composition. The rubber composition contains a rubber component, fine cellulose fibers, and short fibers. The content of the short fibers in the rubber composition is 25 parts by mass or more and 45 parts by mass or less per 100 parts by mass of the rubber component, and the volume fraction of the short fibers in the rubber composition is 12.5 vol % or more.

The present invention pertains to a rubber composition for a transmission belt, the rubber composition comprising: a polymer component including an ethylene--olefin elastomer; carbon black; and clay. The Mooney viscosity of the ethylene--olefin elastomer at 125 C. is 25 ML(1+4)@125 C. or less, and the pH of the clay is 5.5 or higher. The total amount of the carbon black and the clay is 80-180 parts by mass per 100 parts by mass of the polymer component, and the mass ratio of the clay to the carbon black is clay/carbon black=0.2/1 to 1.2/1.

The present invention pertains to a rubber composition for a transmission belt, the rubber composition comprising: a polymer component including an ethylene--olefin elastomer; carbon black; and clay. The Mooney viscosity of the ethylene--olefin elastomer at 125 C. is 25 ML(1+4)@125 C. or less, and the pH of the clay is 5.5 or higher. The total amount of the carbon black and the clay is 80-180 parts by mass per 100 parts by mass of the polymer component, and the mass ratio of the clay to the carbon black is clay/carbon black=0.2/1 to 1.2/1.

Poly-V belts are disclosed that have a body in an elastomeric material, preferably EPDM, a plurality of durable filiform inserts longitudinally embedded in the body, and a coupling portion integrally connected to the body and comprising a plurality of V-shaped ribs in side by side arrangement alternating with V-shaped grooves. A layer of a thermoplastic material at least partially covers the ribs, and a knitted fabric is arranged over the thermoplastic material. Preferably, the thermoplastic material includes a polyolefin irradiated with a dose amount of radiation between 60 and 140 kGy.

A cross-linkable nitrile rubber composition including a highly saturated nitrile rubber (a) containing ,-ethylenically unsaturated nitrile monomer units and ,-ethylenically unsaturated dicarboxylic acid monoester monomer units and having an iodine value of 120 or less, organic staple fiber (b) with an average fiber length of 0.1 to 12 mm, and a polyamine cross-linking agent (c) is provided. The cross-linkable nitrile rubber composition able to give cross-linked rubber excellent in tensile stress and low heat buildup can be provided.

A cross-linkable nitrile rubber composition including a highly saturated nitrile rubber (a) containing ,-ethylenically unsaturated nitrile monomer units and ,-ethylenically unsaturated dicarboxylic acid monoester monomer units and having an iodine value of 120 or less, organic staple fiber (b) with an average fiber length of 0.1 to 12 mm, and a polyamine cross-linking agent (c) is provided. The cross-linkable nitrile rubber composition able to give cross-linked rubber excellent in tensile stress and low heat buildup can be provided.

This disclosure describes systems and methods which utilize organoclays compounded with zinc acrylates to improve the performance of drive belts. In performing research on organoclays, the inventors created formulations and methods of compatibilizing organoclays with metal salts of --unsaturated organic acids and incorporating the compatibilized organoclays into the belt compound so that the planar organoclay particles are substantially aligned with the longitudinal plane of the belt. This is shown to provide a) lower Mooney viscosity (resulting in greater ease of processing), b) higher stiffness (both tensile and dynamic) c) improved tear resistance, d) lower crack growth rate and e) nearly equivalent fatigue resistance in spite of the increased stiffness. This combination of traits in the belts created utilizing the organoclay/zinc acrylate technology described herein results in an unexpectedly improved belt.

This disclosure describes systems and methods which utilize organoclays compounded with zinc acrylates to improve the performance of drive belts. In performing research on organoclays, the inventors created formulations and methods of compatibilizing organoclays with metal salts of --unsaturated organic acids and incorporating the compatibilized organoclays into the belt compound so that the planar organoclay particles are substantially aligned with the longitudinal plane of the belt. This is shown to provide a) lower Mooney viscosity (resulting in greater ease of processing), b) higher stiffness (both tensile and dynamic) c) improved tear resistance, d) lower crack growth rate and e) nearly equivalent fatigue resistance in spite of the increased stiffness. This combination of traits in the belts created utilizing the organoclay/zinc acrylate technology described herein results in an unexpectedly improved belt.