Abstract: The object of the present invention is to provide an polymerization method for carboxylated styrene-butadiene latex using paper coating with the gel content having 50%.about.90% by controlling the reaction with the sole use of tertiary-dodecyl mercaptan in the high temperature polymerization method with following steps comprising;i) reacting and batch charged polymerizing 10.about.20 wt % of total styrene and butadiene monomers with small quantity of acid monomers, emulsifier, initiator and reducing agent at about 60.degree. C. in initial polymerization step; andii) reacting and continuously charged polymerizing 80.about.90 wt % of total styrene and butadiene monomers with small quantity of acid monomers, emulsifier and tertiary dodecyl mercaptan as chain transfer agent with increasing the polymerization temperature step by step from 70.degree. C., 75.degree. C. to 80.degree. C. in increment polymerization step.