Tall Oil

Abstract Tall oil, a by‐product of kraft pulping of pine wood, is formed by acidifying black liquor soap skimmings. It consists of resin acids or rosin, fatty acids, and neutrals. Crude tall oil is an excellent source of rosin and tall oil fatty acid, an industrial‐grade oleic and linoleic acid blend. Extensive fractional distillation is required. The bulk of the neutrals, largely esters of fatty acids, sterols, resin and wax alcohols, and hydrocarbons, boil at either lower or higher temperatures than the boiling range of the fatty and resin acids. Tall oil fatty acid is used to manufacture drying alkyd resins and dimer acids. Dimer acids are converted to noncrystalline polyamides with low softening points and transition temperatures. These polyamides find application in hot‐melt adhesives, printing ink resins, and epoxy curing agents. Rosin is used mainly in printing ink and adhesives and, to some extent, as emulsifier in the manufacture of styrene–butadiene elastomer rubber and paper size.