US 2250185 A
Description (OCR text may contain errors)
Patented July 22, 1941 Orville E. Mohler, Glendale, calla, assignor to 'Socony-Vacuum Oil Company, Incorporated,
New York N. I a corporation of New York No Drawing. Application September 1, 1939,
I Serial No. 292,992
The object of the invention is to provide a heat reflecting, corrosion preventing coating material for metal surfaces which may readily be removed when itsusefu lness is at an end.
In such service as, for example, shipping aeroplanes ortheir parts by sea, it is necessary to cover the bright metal parts with a coating which will protect them from corrosion by salt spray, to which the alloys of aluminum are particularly subject.
The compounds heretofore used for that purpose have been dark colored and cause the absorption by the metal of excessive quantities of heat, causing abnormal expansion and undue stresses in riveted joints, particularly over large surfaces such as wings and bodies.
having a boiling range from 300 to 400 F., and is preferably prepared from a naphthenic crude. Such solvent is miscible with any of the above resins when molten and gives a clear'solution I propose for this purpose, a compound con- 'sisting of an oil soluble resin, a solvent, and aluminum powder, brought to the consistency of a moderately thick paint to be applied witha brush or an air spray. A typical composite for this purpose may have the following formula:
Petroleum resin per cent 15to 50 Petroleum solvent do 85 to 50 Aluminum powder pounds per gallon /2 The petroleum resin may be a water-insoluble.
naphthenate of one of the metals, as for example of zinc, copper, calcium, or magnesium, or it may be the residue resulting from the treatment of petroleum acids with formaldehyde and consist- I ing of the formaldehyde condensation products of phenols, cresols, etc., naturally occurring in the crude, or it may be the residue resulting from the distillation of acid-treated pressure distillate from a petroleum cracking operation, and which consists of condensation products of the unsaturated bodies occurring in such distillate. Some or the naphthenates of the above metals produce a somewhat sticky coating, while the other resins described, when distilled down to a hard solid consistency, yield strongly adherent, hard coatlngs, which are strongly resistant to weathering and to penetration by salt or other-corrosive agents.
The petroleum solvent should be a distillate which dries rapidly at atmospheric temperature but not toorapidly for application by brushing;
The solutions above are dark in color and those of the second and third resins leave a blackish filmon application and when dry. However, when aluminum powder is added to the solution the leafing action of the aluminum powder causes it to rise to the surface and give a bright aluminum surface irrespective of the dark color of the vehicle. Experiment has shown that aluminum alloy surfaces coated with the finished product and placed in the noonday sun reached a temperature averaging 25 Fahr. below that reached by similarly treated surfaces which had been coated with a transparent, dark colored corrosion-resisting compound.
All of the above compounds are readily soluble -this they difier from all the drying oils which on exposure in thin films lose their solubility in petroleum distillates and can be removed only with considerable difliculty.
I claim as my invention:
A composition for forming a heat-reflecting, corrosion-resisting, easily removable coating, comprising: a suspension of aluminum powder in a solution consisting of 15% to naphthenate of a metal selected from the group comprising zinc, copper, calcium, and magnesium and to 50% of a volatile petroleum solvent, said suspension'being compounded inthe proportions of approximately V2 pound of aluminum powder per gallon of said solution;
ORVIILE E. MOHLER.