Oxidized Turpentine Preparation and Use in Lacquer Formulation PAULM. HORTON AND W. F. MCCORMICK, Louisiana State University, Baton Rouge, La.
0
XIDIZED, or thickened, turpentine has been produced abroad, imported into this country under the name of "fat oil," and consumed for the most part in the manufacture of liquid gold and decorative enamels employed in certain ceramic decorative processes. The price has been generally high, owing to the primitive method of manufacture; this consists of exposure of turpentine in flat pans and recovery of the thickened residue. The yield is low but the product obtained is light in color. Methods using elevated temperatures, together with various catalysts for accelerating thickening, ordinarily yield a darker product which is not acceptable for all purposes. I n this laboratory thickened turpentine has been produced by simple air oxidation; a closed circulating system is employed in which the liquid is passed through a heater and injected into the top of an uninsulated tower of Pyrex glass tubing packed with glass rings. Aluminum or enameled steel construction may be substituted for glass, but i t has been determined that copper, iron, lead, and zinc are quickly corroded and taken into solution. Air is metered into the top of the tower where it contacts the liquid a t a temperature of approximately 140" C., passing concurrent and out of the bottom of the tower at about 70" C. The air is eliminated through a condenser, while the liquid flows to a receiver for recirculation. In the authors' equipment using a 3-inch (7.6-cm.) tower 3 feet (91 cm.) in height, a batch of 20 liters after 100 hours of operation has assumed a golden color and has become slightly sirupy in consistency. Following reduction by steam distillation to about 50 per cent of its volume, the light oil remaining possesses a viscosity of 30 seconds Saybolt at 200" F. (93.3" C.). Concentrated further to 25 per cent of the original volume, the viscosity is about 105 seconds, The steam distillate may be re-used with an overall yield of about 80 per cent. The heavy oil when painted on a smooth surface will, in time, dry to a shellac-like film. It has been shown experimentally to be identical with the fat oil of commerce. The light oil is used in lacquer formulation. During the course of an investigation designed to extend the use of this material, it was determined that considerable quantities could be incorporated in the usual formulas for the preparation of nitrocellulose lacquer. It is compatible in all solvent mixtures studied and imparts interesting properties to the films produced either by brushing or spraying. The f a t oil is nonvolatile and can be used in sufficient quantity to produce a highly plasticized coating during the stages of application and preliminary drying. The film is not sticky or extremely tender, as is the case with films highly plasticized with some commercial plasticizers. Following the preliminary set, the fat oil in the film rapidly hardens and imparts to the film the properties usually obtained by the use of various resins, so that resins may be used in less than the usual quantities. Films containing fat oil exhibit a natural high gloss. F a t oil, therefore, acts as both a plasticizer and a hardener, and may be used in amounts up to 25 per cent of the volume of the lacquer with excellent results. Coatings have been formulated which are practically scratch-proof, possess high natural gloss without polishing, and show remarkable resistance to steam and ultraviolet light. Fat oil in the amounts recommended yields a clear
lacquer possessing a natural golden oak color that does not fade. It cannot be used in pigmented lacquers of certain pastel shades. Anyone interested in the preparation of experimental batches of lacquer will find the following formulas suggestive. They are both of the brushing type suited to finishing wood. Half-second cotton was used and no tests were made on 5second or other grades of nitrocellulose. Formula 2 is similar to varnish in its brushing properties, coupled with quick drying :
-
FORMULA la
-FORMULA
2b-
% by vol. F a t oil 6.8 Ethyl acetate 6.6 Butyl alcohol 10.0 Cellosolve 17.5 Turpentine 10.0 Toluene 25.0 Butyl stearate 3.3 Dammar s o h . 20.8 5 Half-second R. S. dry nitrocellulose, 200 grams per liter of solvent. The cotton is softened in the solvent. omitting the toluene and fat oil which are added after solution of the cotton is complete. b Half-second R. 9. dry nitrocellulose. 150 t o 180 grams per liter. The dammar solution is prepared by dissolving dammar resin in an equal weight of a solvent consisting of 70% toluene, 15% ethyl acetate, and 15% benzene and pouring into an equal volume of methyl alcohol to dewax; the dewaxed solution contains approximately 20% of dammar resin. % by vol.
F a t oil Ethyl acetate Butyl alcohol Butyl acetate Butyl stearate Toluene Copal s o h . (20% in solvent)
19.5 10.6 11.7 27.2 3.7 19.5 7.8
Test panels carrying three coats applied 1 hour apart were allowed to dry for 24 hours and subjected to the action of live &earn for 4 hours. The panels, after drying,. provided the steam had not removed the gloss, were placed in a warm closet maintained a t 60" C. where they were subjected to the radiation from a laboratory mercury arc a t a distance of approximately 14 inches (35.6 cm.) for 12 hours. Observations were made for peeling, checking, and loss of gloss. Breakdown tests were not made, since the conditions chosen resulted in loss of gloss or checking in the case of some commercial lacquers available at the time. About two hundred variations in formulation were tested with a few failures, Formulas similar to those given above have been subjected to outside service tests for 3 years without failure, The authors believe the use of fat oil simplifies the formulation of serviceable brushing lacquers. RECEIVEDJuly 24, 1934.
NOTETO THE EDITOR. With reference to the paper entitled "Line Coordinate Charts for Vapor Pressure-Temperature Data" by Germann and Knight on pages 467 to 470 of the April number of INDUSTRIAL AND ENQINEERING CHEMISTRY, I would like to point out that I published some alignment charts for vapor pressure data in a paper in the Transactions of the Znstitulion of Chemical Engineers (London), 10, 112-52 (1932). These charts differ from that of Germann and Knight in showing the application of Diihring's rule and the methods of Cox [IND.ENQ. CHEM.,15, 592 (1923)], of White [Ibid., 22, 230 (1930)], and of Maxwell [Zbid., 24, 502 (1932)l. In drawing your attention to this point I desire merely t o amplify the bibliography given in Germann and Knight's paper and not to criticize or detract from the value of their work. 38 VICTORIA ST. LONDON,9. W. 1, ENQLAND September 5, 1934
1226
A. J. V. UND~RWOOD
