The Uses of Gum Rosin
Rosin is an ingredient in printing inks, photocopying and laser printing paper, varnishes, adhesives (glues), soap, paper sizing, soda, soldering fluxes, and sealing wax. Rosin can be used as a glazing agent in medicines and chewing gum. It is denoted by E number E915. A related glycerol ester (E445) can be used as an emulsifier in soft drinks. In pharmaceuticals, rosin forms an ingredient in several plasters and ointments.
Printing Inks Industry
Rosin mainly act as color carrier and enhance color adhesive ability in printing ink. It takes about 7% of quality of printing oil in China. Rosin is converted into modified phenolic rosin with softening point of 160 to 175 Celsius degrees and below 20 acid value when it is used in offset printing ink producing. In photogravure printing ink producing, rosin firstly is converted into metal salt rosin with softening point of 125 to 135 Celsius degrees and below 95 acid value. For polymerized rosin, it can be used to producing various special printing ink.
Paints & Coating Industry
Rosin is a basic material for paint industry because rosin is easy to dissolve in alcohol, gasoline, turpentine and others organic solvent. Rosin always is converted to resinate, and then refine with drying oil such as tung oil and mix with volatility solvent to produce various lacquers. Rosin also take important role in producing road coating, rosin firstly converted to rosin malefic ester or polymerized rosin or disproportionated rosin Polyols ester, and then used to make thermoplastic coating for road sign inunction.
Most rosin was applied to papermaking industry as sizing agent. Rosin paper sizing agent can prevent printing oil soaking and dispersing from paper, improves the strength and smoothness of paper; enhances the anti-abrasion of paper. But crystal rosin is unfit for making paper sizing agent due to difficulty of saponification, subsequently makes spot on the paper; sometimes even makes the pipe jam in paper sizing agent producing.
Synthetic Rubber Industry
Rosin is used as softener in synthetic rubber industry; it enhances the plasticity, tear strength, heat resistance, flexibility and anti-abrasion of synthetic rubber; also rosin can be use as dispersant and emulsification in synthetic rubber industry. After seventies of twenty century, about 20% of total annual output of rosin was used synthetic rubber industry.
Traditional aquatint rosin is explosive; several fires in art schools were reported as being due to Aquatint box explosions. The fire hazard is often exacerbated by metal bearings in the rosin box, and the use of a naked flame for melting the rosin dust particles onto a plate. Rosin dust is allergenic, i.e. it is known to cause asthma, and is suspected of permanently clogging lung tissue. Heated rosin is also used as solder flux in the electronics industry. The fumes generated may cause bronchial inflammation. Following lawsuits, the Australian electronics industry introduced tight regulations and safety measures for the use of rosin, which is now used in fully contained working environments such as ventilated glove cabinets. Yet many art schools and print shops still practice traditional rosin based aquatint with minimal precautions.