Rosin Esters
Properties and Applications
Rosin, also called resin acid or colophony, is a natural occurring resin derived from pine and spruce trees. It is one of the oldest raw materials. The three most important types are gum rosin, wood rosin, and tall oil rosin.
Gum rosin is the oldest commercial sources of rosin and one of the oldest resinous raw materials. The raw resin is the exudate of plants and trees. Commercial gum resin is harvested from pine trees by periodically wounding the tree and collecting the sap.
Wood rosin is harvested from the stump of pine trees by multiple extraction and distillation to gain food-grade gum. It can be produced in color grades comparable to gum grades and is used for similar applications.
Tall oil rosin is a by-product of the Kraft process of wood pulp manufacture when pulping pine trees. It is one of the main by-products after lignin and hemicellulose. Tall oil resin has a stronger odor and contains noticeable amounts of sulfur but when highly distilled has properties similar to wood and gum rosin.
The acidic resins are usually converted to esters to improve their miscibility with other polymers.
They are very effective tackifiers but are more expensive than hydrocarbon resins but cheaper than polyterpenes. They are extensively used as tackifiers, compatibilizing agents and performance modifiers in a wide variety of products including printing inks, lacquers, cosmetics, gum, sealants, caulks, tapes, and adhesives.