Patent ID: 9664252
Date: 2017-05-30
CPC Classifications: C08K,C08L,F16G

Claim:
1. A power transmission belt used by being wound around a flat pulley so that an outer peripheral surface of the belt contacts with the flat pulley, comprising: (a) a portion forming the outer peripheral surface made of a rubber composition; (b) an adhesive rubber layer; (c) a cord embedded in the adhesive rubber layer; and (d) an inner peripheral rubber layer attached to the portion (a) through the adhesive layer; wherein the rubber composition comprises: 100 parts by mass of ethylene-propylene-diene terpolymer as a rubber component, 30 to 70 parts by mass of an unsaturated metal carboxylate salt, 5 to 25 parts by mass of carbon black, and an organic peroxide as a crosslinker; wherein the ethylene-propylene-diene terpolymers has a Mooney viscosity ML wherein a total of 35 to 95 parts by mass of the unsaturated metal carboxylate salt and the carbon black are added relative to 100 parts by mass of the rubber component, and an mass ratio of the unsaturated metal carboxylate salt to the carbon black (unsaturated metal carboxylate salt/carbon black) is 1.2/1 to 14/1; wherein dynamic viscoelasticity properties of the crosslinked rubber composition in a belt length direction satisfy: ((a loss tangent tan δ at a temperature of 25° C. and a dynamic strain of 3.0%)/(a storage elastic modulus E′ at a temperature of 25° C. and a dynamic strain 3.0%))×1000<3.0 MPa