Method of preparing latex for coating paper

The present invention relates to styrene-butadienie latex, specifically a method of preparing latex for coating paper which shows excellent adhesion while maintaining printing property and comprised in a composition for coating paper. To achieve the object of the present invention, it provides a method of preparing styrene-butadiene latex comprising the step of emulsion polymerization by adding 0.1 to 10 parts by weight of chain transfer agent comprising; i) monofunctional thiol compound, and ii) polyfunctional thiol compound having at least two thiol groups based on 100 parts by weight of styrene-butadiene monomer composition. The latex prepared by the present method can easily control molecular weight and gel content, so that polymerization stability and mechanical stability are improved and thus, it is possible to print paper with high speed and to improve adhesion.