The invention provides a preparation method of
emulsion-polymerized
styrene butadiene rubber. The preparation method is characterized in that an irreversible addition-fragmentation
chain transfer agent with the following general formula is adopted; an aqueous phase is prepared and then an
oil phase is prepared; after the irreversible addition-fragmentation
chain transfer agent is dissolved in
styrene, butadiene is added into a reaction
bottle, the temperature is reduced, and a emulsification reaction is conducted for 15 to 30 minutes; finally, an oxidant organic liquor is added into the reaction
bottle; after a conversion rate reaches 60 percent to 70 percent, a terminator liquor is added into the reaction
bottle and a
polymerization termination reaction is conducted for 5 to 10 percents; after the
polymerization termination reaction is fulfilled, a demulsification reaction is conducted with solvents of
sulfuric acid and a
methanol to form gel; and after the gel is milled and dried, the low temperature
emulsion-polymerized
styrene butadiene rubber is obtained. Compared with data of traditional
emulsion-polymerized
styrene butadiene rubber using tert-dodecyl mercaptan as a molecular weight
regulator, the preparation method has the advantages that the comprehensive performance is not changed,
odor produced by using
alkyl hydrosulfide is avoided, the
monomer conversion rate is increased by 5 to 8 percent, the product performance is steady, and the reproducibility is high.