In the rubber industry, gum rosin is used as a softening agent to make the rubber soft and easy for kneading, make the filling agent easily dispersed. This gives the rubber elasticity so as to be easily squeezed out by screws in later processing. In addition, this can also help disperse the pigment in the rubber and make the product smooth on surface. With 2-6 percent of gum rosin, rubber will have an increased endurance to laceration and better elasticity.In the synthetic rubber industry, disproportionate gum rosin potash soap is used as emulsifier in the producing of various product including styrene-butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber and acrylonitrile-butadiene-styrene rubber. Since 1970’s, rosin used in the synthetic rubber industry accounts for 20% of the total output of colophony in the world.
Using disproportionate rosin as an emulsifier, rubber product will improve in cohesion; the endurance to heat will increase for 25%. The endurance to both abrasion and laceration of this rubber is better than ordinary styrene-butadiene rubber. The cohesion will be greatly enhanced if blending with natural rubber.