C9 petroleum resin is a kind of thermal plasticizing resin produced by C9 fraction, by-products of petroleum cracking,through pretreat- ment,polymerization and distillation.Featared by acid value, easy mutual solubilities, resistant to water,resistant to ethanol and has the chemical stabilizing property to acid and alkaline, viscosity adjusting and thermal stabilizing.Generally, the petroleum resins are not used independently, but h***e to be used together with other kinds of resins as promoters, adjusting agents and modifiers.