Wood Rosin is an organic compound of a monoterpene, turpentine, and resin acid. Also known as colophony or rosin, it is a solid form of pine oleoresin from pine trees (mostly conifers). It is produced by heating fresh liquid resin in order to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from pale yellow to amber. Rosin is brittle at room temperature but melts at higher temperatures. It is insoluble in water and soluble in organic solvents. Wood Rosin also has a faint piny odor. It consists mostly of different resin acids, especially abietic acid.
When pine trees are harvested, the resinous portions of fallen trees like longleaf and slash pines are collected and then undergo destructive distillation or solvent processes to produce wood rosin.
In solvent processes, the stumps and roots are chipped and soaked in the light end of the heavy naphtha fraction from a crude oil refinery. Multi-stage counter-current extraction is commonly used so fresh naphtha first contacts wood leached in intermediate stages and naphtha laden with rosin from intermediate stages contacts unleached wood before vacuum distillation to recover naphtha from the rosin, fatty acids, turpentine, and other constituents later separated through steam distillation. Leached wood is steamed for additional naphtha recovery prior to burning for energy recovery. After the solvent has been recovered, the terpene oils are separated by fractional distillation and recovered mainly as refined turpentine, dipentene, and pine oil. The nonvolatile residue from the extract is wood rosin of rather a dark color. Upgrading of the rosin is carried out by clarification methods that generally may include bed-filtering or furfural-treatment of rosin-solvent solution.
Adhesives & Sealants Industry
Rosin is widely used as an ingredient of some kind of adhesive, especially in heat melt adhesive, pressure-sensitive adhesive, and rubber adhesive. Rosin mainly is used to enhancing the strength, plasticity, and viscosity of adhesive.
Electrical Equipment Industry
Rosin is used as an insulation material in the electric equipment industry. In China, there is a long history of applying rosin as an insulation material in the cable industry. Rosin can also be mixed with bakelite and other artificial resin to soak and besmear electric loop.
Metal Processing Industry
Rosin is used as a soldering aid and metal polishing agent. Since it has a weak acidity, it is able to remove the oxidation film from the metal surface which slightly erodes the surface of the metal.
Paints & Coating Industry
Rosin is a basic material for the paint industry because it dissolves easily in alcohol, gasoline, turpentine, and other organic solvents. Rosin is converted to resinate, refined with drying oil (e.g. tung oil), and then mixed with volatility solvent to produce various lacquers. Rosin also takes an important role in producing road coating. It is first converted to rosin malefic ester, polymerized rosin or disproportionated rosin polyols ester, which is then used to make thermoplastic coating for road sign injunction.
Most rosins are applied to the paper industry as a sizing agent. Rosin paper sizing agent can prevent printing oil soaking and dispersing from paper, which improves the strength and smoothness of paper and also enhances the anti-abrasion of paper. However, crystal rosin is unfit as a paper sizing agent due to its difficulty of saponification which would subsequently spot the paper or even jam the pipe in paper sizing agent production.
Rosin can replace a part of grease to produce soap because it has a similar character to fatty acid and is cheaper than fatty acid.
Synthetic Rubber Industry
Rosin is used as a softener, dispersant, and emulsification in the synthetic rubber industry. It enhances the plasticity, tears strength, heat resistance, flexibility, and anti-abrasion of synthetic rubber.
In the bactericide industry, rosin can be converted into abietylamine acetate for killing algae, bacteria, mildew, mollusk, and others pest. In the construction materials industry, rosin is mainly used as a concrete frothing agent and floor tiling adhesive. In the food industry, rosin can be converted into hydrogenated rosin which is then used to produce chewing gum. In the printing ink industry, rosin can act as a color carrier and enhance color adhesive ability in printing ink. Polymerized rosin can also be used to producing various special printing ink.