Rubber composition and conveyor belt using same

1. A rubber composition comprising: a diene-based rubber containing a natural rubber and a butadiene rubber; a carbon black 1; and a carbon black 2;

an amount of the natural rubber constituting from 40 to 90% by mass of the diene-based rubber; an amount of the butadiene rubber constituting from 60 to 10% by mass of the diene-based rubber;

a nitrogen adsorption specific surface area of the carbon black 1 being from 60 to 100 m 2 /g; a dibutyl phthalate oil absorption of the carbon black 1 being 120 cm 3 /100 g or less;

a nitrogen adsorption specific surface area of the carbon black 2 being from 20 to 40 m 2 /g; a dibutyl phthalate oil absorption of the carbon black 2 being from 70 to 95 cm 3 /100 g; and

a total amount of the carbon black 1 and the carbon black 2 being from 25 to 50 parts by mass per 100 parts by mass of the diene-based rubber.

2. The rubber composition according to claim 1 , wherein an amount of the carbon black 1 is from 15 to 30 parts by mass per 100 parts by mass of the diene-based rubber.

3. The rubber composition according to claim 1 , wherein an amount of the carbon black 2 is from 15 to 25 parts by mass per 100 parts by mass of the diene-based rubber.

4. The rubber composition according to claim 1 , further comprising sulfur, wherein an amount of the sulfur is 3% by mass or less of the amount of the natural rubber.

5. A conveyor belt produced by using the rubber composition described in claim 1 in a top-surface-cover rubber layer.