C9 petroleum resin is a kind of light yellow granular thermoplastic solid resin, which is mainly divided into raw materials by the carbon nine fraction produced by-product from the ethylene plant. It is produced by polymerization through a special production process under certain temperature and pressure conditions. Low molecular weight polymers with molecular weights between 300-3000. It has the characteristics of low acid value, good miscibility, water resistance, ethanol resistance and chemical resistance. It is chemically stable to acid and alkali, and has the characteristics of adjusting viscosity and thermal stability. C9 petroleum resin is generally not used alone, but as an accelerator, regulator, modifier and other resin together.
The softening point of petroleum resin is one of the most important indicators to measure the performance of the resin, it depends on the relative molecular mass, and is usually used as the basis of petroleum resin classification. The most commonly used softening point in industry is 90 ~ 110 ℃, and its relative molecular mass is between 1 000 ~ 1 400. The highest softening point can reach 140 ~ 150 ℃, the lowest is 20 ~ 30 ℃. Petroleum resins with a relative molecular mass of less than 600 are liquid. Petroleum resin is very soluble in petroleum solvents, and has good compatibility with rubber and other resins, and has good aging resistance.
Petroleum resin has both softening and thickening effects in rubber, as well as filling and reinforcing effects. Generally, those with a softening point below 100 ℃ are called rubber petroleum tackifying resins, and those with a softening point above 120 ℃ are called rubber petroleum reinforcing resins. They can completely replace the coumarone (benzofuran-
Indene) resins and partial replacement of rosin and other natural resins are more ideal compound materials in rubber processing, and their usage is rapidly increasing.