Methyl butadiene styrene rubber and preparation method thereof

The invention provides methyl styrene-butadiene rubber and a preparation method thereof. The preparation method comprises the following steps: under vacuum and nitrogen replacement conditions, carrying out emulsion polymerization reaction by taking alpha-methylstyrene, butadiene, water, an emulsifier, an electrolyte, a reducing agent, a molecular weight regulator and an initiator as raw materialsto obtain an emulsion polymerization product; and when the conversion rate of the emulsion polymerization reaction system is 60-65%, and sequentially adding a terminating agent and a demulsifier intothe emulsion polymerization reaction system to obtain the methyl styrene-butadiene rubber. In the invention, the alpha-methyl styrene and butadiene are used as main raw materials to prepare methyl styrene-butadiene rubber through emulsion polymerization reaction; the glass-transition temperature of the methyl styrene-butadiene rubber is -70 DEG C or below, the content of bound alpha-methyl styreneis 8-15%, the Mooney visco