Power transmission belt

Abstract

A power transmission belt with a good balance of high temperature resistance, good belt durability and low temperature flexibility, and a service range of about −40° C. to about 140° C. The main belt body portion of the power transmission belt is manufactured from an elastomeric material comprising 100 parts by weight of an at least partially hydrogenated nitrile group-containing copolymer rubber, and from about 0.5 to about 50 parts per hundred weight of said rubber of a fiber reinforcement having a length to diameter ratio of greater than 10:1. The nitrile group-containing copolymer rubber preferably comprises (1) from about 5 to about 40 percent of unsaturated nitrile monomer units, (2) from about 1 to about 80 percent of units of at least one second monomer selected from the group consisting of fluorine-free unsaturated carboxylic acid ester monomer units and fluorine-containing vinyl monomer units, or any monomer possessing the characteristic of lowering the glass transition temperature of the rubber; (3) up to about 20 percent of conjugated diene monomer units and (4) the balance being hydrogenated conjugated diene monomer units, preferably wherein the sum of the contents of the monomer units (1) and (2) is preferably from about 30 to 90 percent by weight and the sum of the contents of the monomer units (3) and (4) is from about 10 to about 70 percent by weight. The use of the fiber reinforcement in the nitrile group-containing, highly saturated copolymer rubber provides substantially improved low temperature crack resistance while improving the high temperature resistance of the belt.

Dependencies are inferred from the claim text.