Potassium Soap of Disproportionated Rosin is produced by disproportioned rosin reacting with Potassium hydroxide, which can be used as emulsifier for emulsion polymerization in producing SBR, Neoprene, NBR synthetic rubbers and ABS plastics. It can improve the stickiness and plasticity of synthetic rubbers, so as to increase its strength of heat resistance, tearing and abrasive resistance.