US2374565A - Rust preventive compositions - Google Patents

Description

lar weight carboxylic acids.

such properties as melting Esters and/or salts of high molecular Patented Apr.,24,1945

UNITED STATES 2,374,565 PATENT OFFICE RUST PREVENT IVE COMPOSITIONS Harry Roden, Port Neches, Tex.,

assignor, by

mesne assignments, to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application May 31; 1941, Serial No. 396,169

6 Claims. (Cl. 106-14) act upon the corroded metallic surface in such a manner as to separate the chemically-laden rust from the base metal and provide a protective film on the base metal which repels any corrosive action of the surrounding media and prevents further encrustation of the existing chemical rust. In order for such compositions to be efiective they must be able to penetrate through a body of rust and surround and isolate the rust particles so that the particles are rendered inactive and free from the base metal. Further, these compositions must possess the property of self-healing flowing or leveling off of the protective film to "heal any scratches or abrasions occurring after application, or such rough or pitted area which may be bridged over during the application so that the resulting protective film covers the entire area of the base metal to be protected. As

' distinguished from the former drying films, these compositions should be moisture-proof and should not soften or hydrolyze under continued water submersion, with the resultant eilectv that any undermining, due to the pressure of moisture, is reduced to a minimum.

The present invention is based upon the discovery of a class of preventive compositions which possess all the above-mentioned properties. These compositions are composed of a homogeneous mixture of mineral oil, amorphous mineral oil wax, wool fat material, and esters and/or salts of high molecu- Since the requirements of these pompositions are so stringent and their service conditions so severe in that they are exposed to all types of corrosive conditions,

ability, wetting power, texture and hardness, become prime factors. It has been ascertained that these properties are directly aflected by the type and quantity of the individual components of composition and their relation one to the other, as, for example, the wax content, the

kind of mineraljoil used, the ratio of wool fat to 'wax, the quantity and viscosity of the oil, the proportions of esters used, etc. Taking into consideration all these factors, it has been found that the optimum proportionate range of the individual components-lie between the following limits:

i r Per cent Amorphous mineral oil wax 50-85 Mineral nil Y 15-40 Wool fa I 1-8 .weight carboxylic acids 0.4-6

and particularly such which may be interpreted as the grease-typ non-drying rust two or .more constituents of varying melting points. In the preferred form, the amorphous mineral oil wax, which constitutes -85% of the composition, is divided into a mixture of a high and low melting point petrolatum in the following proportionate. range:

Per cent Petrolatum (MO-150 F. M. P.) 50-70 Petrolatum (l50-165 F, M. P.) 0-15 The mineral oil component is effective in preventing hardening of the composition and aids inflgiving the desired texture and penetrating ability. It has been found desirable to provide a blend of mineraloils of varying base and viscosity ranges, such as approximately two parts of a residual oil to one part light oil distillate. Among the various oils which may be blended to impart the desired structureand hardness to the final composition are the various base and viscosity cylinder stocks and pale oils. The preferred blends of the mineral oils, as present in the final composition, consist of 10-25% of a cylcous pale oil within the Saybolt Universal viscosity range of 150-250 at 100 F.

The wool fat material is used as a flux and adhesive and possesses excellent wetting powers at low temperatures. This material may be either degras or the esters and acids of wool fat. The final component, namely the esters and/or salts 'of high molecular weight carboxylic acids, have been found to possess exceptional wetting, penetrating, texture improving, andcohesive properties'when Present in compositions of this type in point, penetrating These components may further consist of mixproportions of from 0.4 to 6%. Among the esters and salts found to be particularly suitable are the heavy metal salts and alkyl esters: of fatty acids, and particularly the high molecular Weight fatty acids of the type of stearic acid. The alkyl radical of the alkyl esters preferably contain from l-5 carbon atoms. These esters and salts may be used singly or in combination with oneanother, depending upon the type of propertie desired in the'final' composition. However, when using a combinationof these two, it is preferred to have. them present in the final product within the following proportionate ranges:

Per cent Heavy metal salt 0.4-1.0 Alkyl ester 1-5 time the pale oil is added and the mix again stirred until uniform. The high and low melting point petrolatum and wool fat is then added and I the kettle heated to 275 F. for at mixing until all the material the contents of least one hour, with 'is melted. The mixture is then cooled to 150- 160 F. and the alkyl fatty acid ester and a solvent, such as naphtha, are added. After thoroughly mixing until the contentsoi .the kettle are homogeneous, the compound is drawn at a temperature of 135-140" F. Before application of these compositions to a metallic surface, the consistency of the composition may be altered by the I addition thereto of naphtha to facilitate application. Additions of from to 30% naphtha to the base compositionmay be necessary to obtain a spraying or brushing consistency. In the event the application is to be made at low temperatures, such as 40 to 50 F., more solvent may be added.

An additional feature of the invention is the incorporation of an inorganic corrosion inhibitor in the composition when the product is applied to damp or -wet surfaces where the problem of corrosion is more pronounced. Among the corrosion inhibitors found desirable are the basic alkali metal chromate inhibitors which may be incorporated in the-composition in proportions of from 0.5 to 2.0%. The preferred corrosion inhibitor is prepared by adding a 50% solution of sodium chromate (made alkaline to pH 9.5-10.0 with caustic soda) to wool grease and stirring and working at room temperature until an emulsion of the chromate solutionin' wool grease is formed. To this emulsified chromate solution small amounts of solvent are added and stirreduntil the mass as es a soft jelly-like consistency. This jelly i then readily dispersed in additional solvent by agitation and a satisfactory wool grease-chromate solvent inhibitor is formed having the following composition:

Wool grease per cent by weight-.. 28.6 Sodium chromate (50% solution) per cent 50.0 Solvent do 21.4

Wool grease per cent by weight.-- 25-35 Sodium chromate (50% solution) per cent 40-60 Solvent do 20-30 i As a specific example of the compositions of the present invention, the following composition is presented, together with its preparation:

. -Per cent Petrolatum (148 F, M. P.) 57.0 Petrolatum (160 F. M. P.) 10.6

Cylinder stock (Vis. S. U. 155163/210 14.5

v 2240 pounds of cylinder stock. (Vis. SQU. 1 55- 163/210 F.) are mixedwith 86 pounds of aluminum stearate' at roomtemperature.

uniform. To the mixture are added 1530 pounds of pale oil (Via. B. U. 200-216/100 F.) and again Percent Petrolatum (MO-150 F. M. P.) 50-70 Petrolatum (150-165 F. M. P.) 0-15 Cylinderstock 10-25 Viscous pale oil -Q. 5 -15 Wool f t 1-8 Heavy metal salt of a high molecular weight fatty acid 0.4-1.0 Alkyl ester of a high molecular weight fatty acid 1-5 Pale oil (Vis. S. U..200216/ F.) 10.1

Wool grease 3.88 Aluminum stearate 0.59 Butyl stearate 1.33 Chromate inhibitor 2.00

This is stirred without heating until the mass becomes Sodium chromate (50% aqueous alkaline stirred until uniform. 8670 pounds of petrolatum (148 F. M. P.) and 1618 pounds'of petrolatum (160 F. M. P.) are added at the prevailing transfer temperature, and thereafter 590 pounds of wool grease are added at normal temperature. The temperature of the mix is'raised to 275 F., with stirring for at least one hour, after all the material is melted. The mix is then cooled to -140 F. and a dispersion of 300 pounds of the I chromat inhibitor in 200 pounds pf butyl stearate added. After thoroughly mixing, the temperature of the mix should be approximately F., and it should bestirred for at least 20 minutes. The compound is then drawn at a temperature of'135 to 140 F.

It is to be understood that other addition agents may be added to the compositions of the. present invention as desired. Among such addition agents are odorants,- such aspine tar oil, and coloring agents, such as carbon black, graphite, iron oxide, etc.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim: I

1. A non-drying rust preventive base comprising the following formula:

2. A non-drying rust preventive base comprisv ing the following formula:

, Per cent Amorphous mineral oil wax 50-85 Residual mineral oil 10-25 Light mineral oil distillate 5-15 Wool fat 1-8 Heavy metal salt of a high molecular .weight fatty acid 04-1.0 Alkyl ester of a high molecular weight fatty acid Corrosion inhibitor 0.5-2.0

3. Composition as claimed in claim 2 in which -the corrosion inhibitor is composed of the following ingredients: v

Per cent Sodium chromate (50% aqueous alkaline solution) 40-60 Hydrocarbon solvents. 20-30 4. Composition as claimed in claim 2 in which j the corrosion inhibitor is composed of the following ingredients;

- Per cent Wool grease 28.6

solution) 50.0 Hydrocarbon solvent 21.4

5. Composition as claimedin claim 1 in which .the heavy metal salt of a 'fatty acid is aluminum stearate. I

'6. Composition as claimed in claim 1 wherein the alkyl ester of a fatty acid is butyl stearate. 7o a HARR Y Room