Method for manufacturing nitrile-based rubber, nitrile-based rubber manufactured thereby, and rubber composition comprising same rubber

A method for preparing a nitrile-based rubber, the method comprising:

• polymerizing a monomer mixture comprising an α,β-unsaturated nitrile-based monomer and a conjugated diene-based monomer in the presence of an emulsifier mixture,
• wherein the emulsifier mixture comprises a first emulsifier comprising a sulfosuccinate ester-based compound, and a second emulsifier comprising a fatty acid or a metal salt thereof, or a rosin acid or a metal salt thereof, each of which has 12 to 18 carbon atoms and a monocarboxyl group, and the first emulsifier and the second emulsifier are included at a weight ratio of 2:1 to 6:1,
• wherein the sulfosuccinate ester-based compound is represented by Chemical Formula 1 or an alkali metal salt thereof:
• wherein
• R and R′ are each independently an alkyl group having 1 to 20 carbon atoms.