This raw material report defines petroleum resins as glass-like oligomers produced by polymerization of by-product streams resulting mostly from the cracking of petroleum hydrocarbons for ethylene production. The technology has its roots in resins made from coal tar byproducts of steel production, such as coumarone and indene. However, only a very small proportion of the production of hydrocarbon resins is from this source today. The three principal raw material streams are now linear C5s, such as piperylene and amylene, cyclic C5s such as cyclopentadiene and aromatic C9 and C10 fractions, heavy in reactive monomers such as styrene.

There are three basic processes for resin production, in order of volume significance:

· Cold Polymerization with aluminum chloride catalyst

· Thermal polymerization

· Cold Polymerization with boron trifluoride catalyst

Aluminum chloride catalysis is used for the production of the most broadly used, so-called C5 aliphatic, and mixed C5/C9 aliphatic/aromatic resins.

Thermal polymerization is used primarily with cyclopentadienic streams, with and without aromatic impurities to make so-called Cyclic resins. Unless modified with subsequent processing, principally hydrogenation, Cyclic resins tend to be low value products with a strong odor and prone to oxidative decay. The low cost of their raw materials, coupled with a low process cost, makes them attractive to produce and market.

Boron trifluoride catalysis is used to achieve properties differentiated from those that can be achieved with aluminum chloride for a given feedstock. They are most often used with lower cost aromatic feedstocks to make so-called C9 resins, where aluminum chloride catalysis has limited application. As a result, boron trifluoride has a somewhat undeserved reputation for products with a strong odor.

All petroleum resins can be hydrogenated to improve color, odor and stability as well as modifying compatibility. Thermally polymerized polymers are usually the focus of this upgrade for two reasons, they tend to be unstable and malodorous and they are the least expensive in terms of hydrogenation process cost. Boron trifluoride catalyzed products are the next most frequently hydrogenated products, with stability being less of a problem and hydrogenation process cost, while higher than for thermal resins, is generally lower than aluminum chloride catalyzed products. This last category is rarely hydrogenated because of the adverse process economics. For the purposes of this study, no distinction is made between types of hydrogenated hydrocarbon (H2) tackifier.

Petroleum resins, as is the case for all tackifiers, are mostly used in adhesives as modifiers for polymers that have been selected for the specific end-use purpose. In a phrase, they are used to add character, or to differentiate the polymer and control cost, since in most cases, they are less costly than the base polymer.