Rosin is a kind of natural resin; it is the major product obtained from pine resin. Most rosin is used in a chemically modified form rather than in the raw state in which it is obtained. It consists primarily of a mixture of abietic- and pimaric-type acids with smaller amounts of neutral compounds. It can be converted to a large number of downstream derivatives that are used in a wide range of applications. The derivatives include salts, esters and maleic anhydride adducts, and hydrogenated, disproportionated and polymerized rosins. Their most important uses are in the manufacture of adhesives, paper sizing agents, printing inks, solders and fluxes, various surface coatings, insulating materials for the electronics industry, synthetic rubber, chewing gums and soaps and detergents. At present, the total output of rosin is about 1.2 million tons.
Rosin can be divided into three kinds according to its raw material.
Gum Rosin was made from crude pine resin, which obtained by tapping living pine trees. Crude pine resin was distilled into gum rosin and turpentine in gum rosin factory. The world output of gum rosin is about 650 thousand tons per year. China is the biggest gum rosin producing country; the annual output reaches more than 350 thousand tons in recent years. It takes about 60% of world annual total rosin output.
Tall Oil Rosin
Tall oil, also known as liquid rosin, is a resinous yellow-black oily liquid composed of a mixture of rosins, fatty acids, sterols, high-molecular alcohols, and other alkyl chain materials; obtained as a byproduct in the treatment of pine pulp. The Crude Tall Oil is distilled into tall oil Rosin. The output of Tall Oil Rosin keeps stable in recent years, it takes about 35% to world total rosin output.
Wood rosin was made from pine stump. Pine stump was grinded and extracted in wood rosin factory, and then the produce was refined into wood rosin. US is the world biggest wood rosin producing country, the output reaches its climax of 316 thousand tons in 1950 and the declined to 20 thousand tons in recent years. At present, wood rosin only takes 5% of total output of rosin in the world.
Steam method and indigenous method
The process method of crude pine resin includes steam method and indigenous method. The indigenous method is simple, but the quality of gum rosin is unstable, with low softening point and deep colour. The steam method is more complex, the quality of gum rosin is high, with high softening point and light colour, but the price is higher than those of indigenous method product.