rosin(redirected from rosins)
Also found in: Dictionary, Thesaurus, Medical.
(or colophony), a brittle, vitreous substance varying in color from light yellow to dark red; one of the resinous substances found in pine trees and obtained in the form of residue following distillation of the volatile part from these substances. Rosin has a density of 1.07-1.085 g/cm3 and a softening point of 52°-70°C. A poor conductor of heat and electricity, it dissolves readily in ether and alcohol but is insoluble in water. It is composed of resin acids (80-95 percent) of the general formula C19H29COOH and of neutral unsaponifiable substances (5-12 percent).
Rosin is classified according to the type of raw material and to the method of preparation as follows: gum rosin (obtained by distillation of turpentine oil from refined turpentine), wood rosin (obtained by extraction of wood chips from tarred pine stumps using organic solvents, primarily gasoline), and tall oil rosin (obtained by fractional distillation of crude tall oil, a product of sulfate soap refining). Rosin and its derivatives are used in sizing paper and cardboard; as emulsifiers in the manufacture of synthetic rubbers, elastics, plastics, artificial leathers, linoleums, soap, varnishes, paints, and electrical insulating mastics and compounds; and as a flux in the tinning and soldering of metals.
REFERENCESVasechkin, V. S. Tekhnologiia ekstraktivnykh veshchestv dereva. Moscow-Leningrad, 1953.
Komshilov, N. F. KanifoV, ee sostav i stroenie smolianykh kislot. Mos-cow, 1965.
P. P. POLIAKOV