US2403765A - Mineral oil composition - Google Patents

Description

Patented July 9, 1946 Herschel G. Smith, Wal Cantrell. Lansdowne,

Pennsylva lingford, and Troy L.

Pa., assignors to Gull Oil Corporation, Pittsburgh,Pa., a corporation of nia No Drawing. Application March 19, 1945. Serial No. 583.655

11 Claims. 1

This invention relates to mineral oil compositions. More particularly, the invention is concerned with mineral lubricating oil compositions of a character adapted to protect ferrous and other metal surfaces, to which they are applied. from rusting and other types of corrosion in'addition to affording lubrication of such surfaces.

Simple mineral oil films aflord only a limited protection 'to metal surfaces from rust and other types of corrosion, but do not afiord any great protection under severe conditions of use. Many so-called anti-rust lubricating oils have been proposed, consisting of mineral'oils and added constituents intended to protect metallic surfaces from rust, tarnish or corrosion. Most of them are of rather limited applicability, in that while they afiord satisfactory protection to one class of metals, they may be ineiiective, or even deleterious, with another class of metals.

These shortcomings of such mineral oils and oil compositions are serious in manycases, particularly in cases wherein a plurality of metals must be simultaneously lubricated while exposed to corrosive conditions; for example, in the case of copper-alloy bearings with steel shaft and the case of electric motors where surfaces of both steel and copper are exposed to corrosive conditions. Moreover, many such oils show undue sensitivity to moisture and air and other substances to which they are exposed, and lubricating films of such oils do not effectively protect the metal against rusting or tarnishing when exposed to moisture and air or other corrosive atmosph'eres. It is also found that some compounded oils which are efiectlve as regards preventing rust, are deficient in lubricating properties.

Among the objects of the present invention is the provision of an anti-corrosion lubricating oil composition, of good lubricating properties, adapted to protect steel from rusting while being of itself free from tendency to corrode copper and other metallic surfaces, and being in itself relatively inert and unaffected by air and moisture.

These and other objects of the invention are achieved by the provision of a mineral 011 composition including, as a rust inhibitor, the substantially neutral reaction products obtained by reacting dicyclohexyl amine with acid phosphate esters of alkylated phenols containing at least one branched chain alkyl group, the said amine and acid phosphate esters being reacted in approximately equimolecular proportions under such conditions that the reaction product or mixture has a DH value between 5.5 and 7.5.

2 We have found that such improved oil compositions are very efl'ective as anti-corrosion lubricants for metal surfaces in general. They form tightly adherent oil films on the metal, protecting the metal surfaces from moisture and air. In addition, the improved oil composition itself is free from any tendency to attack copper, steel and other metals by reaction therewith or otherwise. For instance, polished or highly finished steel surfaces protected by establishing and maintaining the improved oil composition on the surfaces thereof remain bright indefinitely and copper alloy bearings (which present a difficult problem in protection from corrosion) are maintained in their highly finished condition even under unfavorable conditions of use. Further, copper, aluminum, zinc, tin, silver, and their alloys are all effectively guarded against corrosion and are well lubricated by these improved oil compositions containing our new rust inhibitors.

In general, various improved lubricants, such as household lubricants, machine oils, gun oils. turbine oils, slushlng oils and the like are prepared, by selecting'a suitable lubricating oil or base and dissolving the required amount of the above described reaction products in the oils.

' In particular, the invention finds special utility in preparing improved oil compositions of the socalled' household type, useful for lubricating light mechanisms such as electric motors, guns, etc., and containing relatively light (low viscosity) oils as the lubricating base. That is, the invention is especially well suited for improving highly refined lubricating oils having aSaybolt Universal viscosity ranging from t0 150 at F.; minerals oils of 100 viscosity being especially suitable for preparing our improved oil compositions.

In general, from 0.01 to 25.0 per cent of the inhibitor is suincient to impart to lubricating oils adequate rust-inhibiting properties. More concentrated oily solutions or oil mixtures 01' the inhibitor can be prepared, as a stock solution or concentrate, which can be diluted with lubricating-oil to form a rust-preventive'lubrlcant, Usually 0.5 per cent or less of the inhibitor is slimcient to impart to mineral lubricating oil adequate rust-inhibiting properties for metal articles exposed to moisture and air, but as much'as 25 per cent by weight on the oil is sometimesincorporated to afford prolonged and complete protection from rust under extremely severe conditions. Such highly concentrated compositions still retain excellent lubricating and other characteristics'in addition toairording practically complete extraor conditions.

rust protection under I thereof The reaction products we employ are relatively stable compositions under ordinary conditions. At room temperatures some of them are heavy viscous oily liquids, while others are soft solids which melt to oily liquids at slightly elevated temperatures. All of them are relatively nonvolatile. They are insoluble in water and more or less water repellant. They are very resistant to hydrolysis. These reaction products or inhibitors are soluble in both mineral and fatty oils. Their solubility varies somewhat with the particular oil. For instance, light paraffinic oils, such as those employed in making household lubricants etc. dissolve approximately 0.1 per cent by weight of these reaction products, forming stable solutions Naphthenic type mineral oils dissolve somewhat larger amounts. In general, the solubility of these reaction products or inhibitors is quite high in most oils.

These advantageous rust inhibitors can be readily prepared from di-cyclohexyl amine and acid phosphate esters of alkylated phenols containing at least one branched chain alkyl group, by reacting said amine and acid phosphate esters together in approximately equimolecular proportions, as stated ante. In preparing our rust inhibitors or reaction products, the reaction is con'- trolled so as to produce substantially neutral reaction products or mixtures having a pH value between 5.5 and 7.5 (as measured with quinhydrone-calomel electrode assembly).

The di-cyclohexyl amine, employed as one reactant, is a well-known chemical compound; it being a secondary amine having the following formula:

. our rust inhibitors may be prepared by directly reacting the di-cyclohexyl amine with the said acid phosphate esters.

The other reactant, the and phosphate esters, are acid phosphate di-esters of di-alkylated phenols, and may be represented by the following generic formula:

wherein R represents a branched chain alkyl group, such as tertiary butyl, secondary butyl. tertiary amyl, di-isobutyl. and like tertiary and secondary alkyl groups, and R represents an alkyl group, advantageously a branched chain alkyl group, such as secondary butyl, tertiary butyl and the like. Thus, the acid phosphate diesters of di-alkylated phenols containing one or two branched chain alkyl groups are advantageous in the practice of this invention, particularl those containing two branched chain butyl groups. preferably tertiary butyl groups.

These acid phosphate esters may be prepared by various methods from alkylated phenols containing one or more branched chain alkyl groups attached to the phenyl nucleus in the positions indicated ante,

In particular, the acid phosphate di-esters of 2-tertiary-butyl-4-secondary butyl phenol, 2,4- ditertiary-butyl phenol, 2,4-ditertiary-amyl phenol, and 2-tertiary-butyl-4-tertiary-amyl phenol are advantageous for the present purposes. For instance, as shown in the illustrative examples post, di-(2,4-ditertiary-butyl phenyl) phosphate having the following formula:

is advantageous in preparing our rust inhibitors. These new acid phospate 'di-esters are viscous oily liquids at room temperature and are readily soluble in mineral oils. Accordingly, mineral oil solutions of these acid phosphate esters may be employed in preparing concentrates of our rust inhibitors in oil; the amine being added to such oil solutions and reacted with the acid phosphate ester dissolved therein to form the rust inhibitor in situ in the oil. In general, acid phosphate diesters of alkylated phenols containing tertiary or secondary alkyl groups are useful and advantageous in preparing our rust inhibitors; those containing a plurality of such tertiary or secondary alkyl groups being particularly advantageous for the present purposes. Such acid phosphate diesters are readily soluble in mineral oils and have other properties rendering them advantageous for the purposes of this invention.

As a class, these acid phosphate di-esters of alkylated phenols containing branched chain alkyl groups react readily with di-cyclohexyl amine. In general, the reaction is exothermic and is quite vigorous in most cases. In preparing our rust inhibitors, the reaction temperature is controlled by suitable means 'to secure smooth reaction and obtain addition products of the amine and acid phosphate ester. In doing so, the temperature of the reaction mixture is controlled by cooling or heating as required; the temperature of the reaction mixture being maintained below 180 F. to avoid splitting out water from the mixture. The reaction temperature is usually maintained between 140 and 170 F. during the larger portion of the reaction and within this range excellent rust inhibitors are obtained; the pH value of the reaction product being adjusted in the final stages of the reaction within the desired range stated ante.

The following examples illustrate advantageous methods of preparing these rust inhibitors:

Example I.--Into a suitable kettle, equipped with means for heating, cooling and agitating the charge, there were added 474 pounds of di-(2,4- ditertiary-butyl-phenyl) phosphate, and then 181 pounds of di-cyclohexyl amine were gradually added with stirring. The reaction was vigorous and exothermic, and the amine was added at such a gradual rate as to facilitate maintaining the reaction temperature below 180 F.; the mixture being cooled if necessary to maintain it below that temperature. In this way, the reaction temperature was maintained between and F.

.5 during the larger part of the reaction. By so controlling the temperature, the side reactions are checked, particularly the splitting out of water from the addition product and conversion of it into the corresponding amide.

After the exothermic reaction had subsided, a further 18 pounds of di-cyclohexyl amine were added to the warm reaction mixture and this mixture stirred until the reaction was complete.

The substantially neutral addition product so obtained was a. heavy, viscous, oily liquid when cooled to room temperature. It had a pH value of approximately 6.8. This amine salt or rust inhibitor had a pleasant odor and a light amber red color. It was soluble in mineral oils and other hydrocarbons. It is an excellent rust inhibitor for the present purposes.

Similar oily rust inhibitors having pH values within the range of 5.5 and 7.5 can be readily obtained by the method described ante. For instance, our new rust inhibitors can also be prepared from other acid phosphate di-esters of alkyl-phenols, as well as from the particular acid phosphate ester employed in Example I. The preparation of another such advantageous rust inhibitor is illustrated in the following example.

Example II.Here again, the reaction is carried out in a. suitable kettle. equipped with means for heating, cooling and agitating the mixture, and the reaction temperature is controlled as described in Example I ante.

Into such a kettle, there were introduced 474 pounds of di-(2-tertiary butyl-4-secondary butylphenyl) phosphate, and then 181 pounds of dicyclohexyl amine were gradually added with stirring. The reaction was vigorous and quite exothermic and the amine was added at such a gradual rate as to maintain the reaction temperature below 180 F.; the temperature being maintained between 140 and 170 F., as described in Example 1.

After the exothermic reaction had subsided, a further 18 pounds of the amine were added to the warm reaction mixture and this mixture stirred until the reaction was complete.

The di-cyclohexyl amine salt so obtained had a pH value of approximately 6.9; this salt being a substantially neutral addition product of said amine and said acid phosphate di-ester. This salt may be represented by the following formula:

wherein R represents a cyclohexyl group. The above amine salt or rust inhibitor was a viscous, oily liquid at room temperature. It had a pleasant odor and a light amber red color. It was soluble in mineral oils and other hydrocarbons. Thus, this rust inhibitor is advantageous for making our improved oil compositions.

In other words, the substantially neutral reaction products obtained in Examples I and II, respectively, like the amine and acid phosphate esters from which they were prepared, are soluble in mineral oils. Accordingly, we sometimes prepare concentrated solutions of these rust inhibitors in mineral oil by forming them in situ in the oil. In such processes, the amine is first dissolved in the mineral oil and then the acid phosphate ester added, the mixture being stirred 75 and maintained at the desired temperature until the reaction is complete and.the mixture has a pH value within the specified range. In preparing such oil concentrates of our rust inhibitors, sometimes additional amine is added in the later stages to adjust the pH value as desired. The concentrates or oil solutions of inhibitor reaction products so obtained are useful addition agents to various types of lubricants. The preparation of such concentrates is illustrated in the following example.

Example III.780 pounds 01 light mineral lubricating oil having a viscosity of 100 seconds SUV at 100 F. were added to an iron vessel equipped with means for heating and cooling and agitation. The initial temperature of the oil was F. To this oil were added 181 pounds of di-cyclohexyl amine, which was thoroughly mixed with the oil by mechanical agitation and the final temperature of this mixture wa 82 F. To the oil-amine mixture, 474 pounds of .di- (2,4-di-tertiary-butyl-phenyl) phosphate were added over a period of two hours, during which time the mixture was agitated and the temperature of the reaction mixture rose to 178 F. After stirring for one hour, the pH of the mixture was 4.8. In order to increase this value to the desired range, 6.0 pounds of di-cyclohexyl amine were added to the mixture and stirred and the resultant mixture had a pH of 6.1. To secure a final adjustment, 7.0 additional pounds of di-cyclohexyl amine were added to the mixture which after stirring for one hour and coolin to room temperature had a pH of 7 .4.

The 'oily mixture prepared in this Example HI can be regarded as a sort of concentrated solution which can be stored indefinitely and incorporated in lubricating oils as desired to prepare commercial anti-rust oils and improved lubricants. I

In general, the rust inhibitors 'or reaction products prepared as described ante, may be dissolved in various types of mineral oils and improved anti-rust and non-corrosive oil compositions obtained which are capable of inhibiting or retarding the rusting of various metals as described. The preparation of such improved mineral oil compositions is illustrated in the following examples. 1

Example IV.-A household-type lubricant was prepared by dissolving 0.5 per cent by weight of the rust inhibitor obtained in Example I in arefined oil.

Example V.Another household-type lubricant was prepared by dissolving 0.5 per cent by weight of the rust inhibitor obtained in Example II in a refl'ned oil.

The properties of tions of Examples IV and V ante as compared with the properties of the base oil employed are as follows: i

Improved lubricant Properties Base oil Ex. IV Ex. V

Gravity, xrr 29. 2 2s. 2 28.8 Viscosity, SUV, F 102 103 103 Flash, 00, "F 330 330 330 Fire, 00, "F 365 300 360 Pour, F -30 -30 30 Color, Saybolt- +7 +5 +6 Carbon residue, per cent Trace 0.01 0. 01 Neutralization No N Nil Nil These improved oil compositions have excellent lubricating properties.

ll k w u the improved oil composi- They also efiectively procompared with the base oil. For instance, in

special corrosion Test No. l, the base oil began to show rust on a steel strip after six hours in the test, whereas after twelve days the improved 011 showed no evidence of rust. In the other and more drastic corrosion tests described post, these improved oils showed even greater superiority over the base oil as regards protecting steel 16 specimens are usually steel, copper, tin and zinc,

and-other metals against tarnish and corrosion. The results of these special corrosiontests are summarizedinthe following table.

' Impovedlnbncant Special corrosion test Base oil Ex. IV -Ex. V

Steel strip Fnlk Pages... Passes. Copper str p do do Do. s iee1 strip n Do. (gopper strip do do Do. 0.

Steel strip; do ".60.... Do. Copper strip .do

The special corrosion tests referred to in the above table were as follows: Text No. 1.-36 cc. of the oil or oil composition to be tested and 4 cc. of distilled water are put in a 1" by 6" Pyrex test tube and a polished strip of copper-or steel is immersed in the liquids. To mix the oil and water 2000 cc. of air per hour are bubbled through the mixture from'a point within the bottom of the test tube. The apparatus is set in a. water bath maintained at 122 F. (50 C.) and the original water level in the tube is maintained by additions of fresh water over 24 hours. The test is continued for twelve days regardless of whether or not the metal strip showed signs of corrosion. This test may also be carried out with other metal strlm such as zinc, silver and tin as well as with copper or steel strips.

' In this test, the lower part of the metal strip is completely immersed in the water and the only way the oil can wet the metal surface is for the oil to creep down over it against the water pressure. Accordingly, rusting immediately begins at the level where the oil and the water meet, un-

less the metal surface is preferentially .wetted 5 by the oil; that is,- unless the oil film is capable of spreading on the metal surface and displacing water therefrom. I

. In other words, this test is rather a drastic one for the protective properties of oils and oil compositions as regards the prevention of rust, tarnish and corrosion. For instance, in this test; ordinarily a steel strip shows rust in about 6 hours and a copper strip will tarnish within approximately 12 hour when an uninhibited oilis so tested. On the other hand, generally the addition of as little as 0.1 per cent by wei ht of our rust inhibitors to the oil will maintain both copper and steel strips free from tarnish and rust for periods up to 12 days, a maximum duration of this test.

Test No. 2.In this test,- 180 cc. of the oil or oil composition to be tested and 20 cc. of distilled water are placed in a 400 cc. beaker, anda polished metal strip is immersed in the oil-water 8 mixture; 2000 cc. of humidified air per hour are passed through the mixture and the apparatus is maintained at 122' F. as in Test No. 1. The water level is maintained by daily additions of distilled water and at the end of 1-2 days the water layer is removed by syphon and fresh water is added. The water removed is analyz d to determine whether the inhibitor is being extracted or leached from the oil solution. Fresh strips are added when the water is changed, so as to present a fresh metal surface to the partially leached oil. This cycle is continued for '72 days unless the test specimen becomes too corroded, making further testing impractical. In this test, the test although other special metals may he used.

Test No. 3.The apparatus outlined in Test No. l is employed and the testing conditions are identical, except that water containing sodium 20 chloride in the concentration equivalent to that of the total salt content of sea water is added instead of distilled water. This is a much more severe test and is conducted also for 12 days, the water level being maintained in the same manner as for Test No. 1.

$0 tack by moisture and air under extremely severe conditions, particularly in Test No. 3. Further, the oil film on the metal and the oil itself are exposed to not only the leaching action of the water but also to oxidation. Accordingly, if

8.5 rusting is prevented under such drastic condltions in these tests, there is good assurance that the inhibitor will be capable of preventing, or at least retarding rusting even under extremely severe service conditions; Therefore, an inhib- 40 itor which when dissolved in an oil permits the oil to pass all three of these tests, is considered an excellent inhibitor.

As shown ante, improved oil compositions containing our rust inhibitors have successfully passed all of these tests. Further our improved oil compositions in addition to having excellent anti-rust properties are also excellent lubricants. Likewise, as shown ante, the anti-rust properties or the improved oil may be controlled'by selecting the rust inhibitor and varying the proportions thereof incorporated in the oil. For instance, in certain special cases, where the prevailing conditions are so extreme as to require the lubricant to be extremely highly protective toward metal surfaces, a higher percentage of rust inhibitor is incorporated in the oil. The following example is illustrative of such embodiments of this invention.

' Example VI .In preparing one such lubricant,

00 0.3 per cent by weight of the rust inhibitor obtainedin Example I was incorporated in a suitable oil base. The oil base selected and the improved lubricant made from it have the following properties:

Base oil Improved oil Gravity, API Q. 5 E. 4 Viscosity SUV F 109 7 Color, NiA. 1.25 1. as

" ditions, even in the presence of salt and salt water. For instance, when tested by the special corrosion Tests Nos. 1 and 3 ante, the improved oil showed no evidence of corroding either copper or steel after 12 days in either of the above tests. On the other hand, the base oil allowed the steel strip to rust in approximately 8 hours in the fresh water (Test No. 1) and in about 3 hours in the salt water test (Test No. 3). Also, with the base oil, the copper strips were coated with a greenish deposit after overnight testing; the

copper strips being more slowly attacked thanthe steel strips but nevertheless substantially tarnished and corroded.

The specific embodiments described above are merely illustrative of the practice of this invention and other embodiments thereof may be used as desired; for instance, these rust inhibitors are compatible with various other compounding in gredients and they may be added to blended oil bases or compounded lubricants to obtain other types of improved lubricants. Improved oil compositions can be prepared from base oils containing varying amounts of fatty oils admixed with mineral oil, such blends being especially useful as household lubricants. By the present invention, any of the previously known household or other lubricants containing relatively light lubricating oils can be improved by adding small amounts of our rust inhibitors as described.

The invention is equally applicable to heavy mineral oils, petrolatum oils, greases, and jellies; in fact to any petroleum lubricant or coating oil, in which corrosion-preventive properties are desired. In the claims the term lubricant includes mineral oils, jellies for purposes other than strict lubrication, e. g., slushing oils and gun greases.

One important application of the present invention is the prevention of rusting in automotive and aviation engines before or after these have been used, either upon aging in intermittent actual awaiting completion of assembly, shipment, and other delays after engine break-in. Such rusting is aggravated by the presence in the crankcase and crankcase-oil of moisture, sulfur, oxidation products from petroleum, tetraethyl lead, de: composition products, etc. Attempts have been made to remedy this condition by washing out all motor oil from the crankcase of an engine if it is to be stored for any appreciable time, or adding compounds containing large amounts of oiliness agents and the like. tion presents a more economical remedy for these conditions, for corrosion is effectively retarded under-such conditions when from 0.5 to 1.0 per cent by weight of our compounds is added to. a used motor oil. Adding the highly potent rust preventive compound during the latter part of the break-in period for the new engine, with operation for sufiicient time after addition to assure full mixing and coating of parts, will prevent rusting.

Extensive tests in which the pH values of the agents of the present invention as employed in finished oils were varied, confirm our discovery that the optimum results for a given amount of the agent in oil are secured when the pH value is maintained within the stated range of 5.5 to 7.5 for the compounding agent. There is usually a slight drop in pH value in the dilute finished oil solution as compared with the values for the compounding agents or mixtures thereof. The

finished oil (which usually contains only a small proportion of the dilute compounding agent) and the like even when used service or in storage of engines or planes The present invenless desirable results. For example, with an unduly low pH value (acid side) there is some rusting of steel surfaces by our steel strip corrosion test, while compositions with an excessively high pH value (alkaline side) may produce greenish corrosion effects on the corrosion tests with copper surfaces and the like, although not affecting steel to any appreciable extent. The exact ad- J'ust-ment is attained in preparing the rust inhibitor compound by reacting the desired molecular proportions of the two agents inthe manner described, and after-the neutralization or compounding reaction has progressed practicallyto completion, testing the reaction product, and making any minor adjustments that are necessary for exact control by adding the required small additional proportion of the amines (if on the acid side of our desired range) or of theacid phosphate ester (if on the alkaline side); In measuring the pH of the anti-rust agents of the which are both substantially water-insoluble, the

sample is dissolved in normal butanol (which I 0 contains a small amount of water) adjusted exactly to pH 7.0. The butanol acts as a blending agent for the water and the relatively insoluble material, but does not appreciably alter the pH value as it is of pH exactly 7 itself. Measurement is made by electrometric or colorimetric procedures; the results agree closely.

This application is a continuation-in-part of application Serial No. 504,056, now issued as Patent No. 2,371,853, of March 20, 1945.

What we claim is: a

1. An improved oil composition, efiective as a lubricant for metal surfaces and capable of preventing corrosion thereof in the presence of moisture and air, comprising a petroleum lubricant containing in solution therein a small proportion of a substantially neutral addition product of di-cyclohexyl amine and an acid phosphate di-ester of a di-alkylated phenol having the following formula: 1 1

wherein R represents a branched chain alkyl neutral addition product of di-cyclohexyl amine and di-(2,4-di-tertiary-butyl-phenyl) phosphate.

3. The improved oil composition of claim 1 wherein said addition productis a substantially neutral addition product of di-cyclohexyl amine and di-(z-tertiary butyl-4-secondary butylphenyl) phosphate.

4. The improved oil composition of claim 1 wherein said addition product is a substantially neutral addition product of di-cyclohexyl amine and di-(2-tertiary--butyl-4-tertiary-amyl-phenyl) phosphate.

5. The improved oil composition of claim 1 wherein said addition product is a substantially advantageously by weight on 11 neutral addition product or di-cyclohexyl amine and di-(ZA-di-tertiary-amyl-phenyl) phosphate.

6. The improved oil compomtion of claim 1 wherein said petroleum lubricant contains from 0.01 to 10.0 per cent by weight of said substantially neutral addition product dissolved therein.

'1. The improved oil composition of claim 1 wherein said petroleum lubricant is a. mineral lubricating oil.

8. An improved oil composition, efiective as a lubricant for ferrous and other metal surfaces and capable of preventing corrosion thereof in the presence of moisture and air, comprising a mineral lubricating oil and 0.01 to 10.0 per cent the oil of a substantially neutral addition product of di-cyclohexyl amine and an acid phosphate di-ester of a di-alkylated phenol having the following formula:

wherein n represents a; branched chain alkyl 25 stantially neutral addition product having a pH between 5.5 and 1:5 and the proportion thereof dissolved in the lubricant being sufficient to prevent rusting of ferrous metals.

9. The improved oil composition of claim 8 wherein said mineral lubricating oil is a light mineral oil having a Saybolt Universal viscosi y between and 150 seconds at F.

10. The improved oil composition of claim 8 wherein the addition product is a substantially neutral addition product of di-cyclohexyl amine and di-(2,4-di-tertiary butyl-phenyl) phosphate.

11. An improved oil composition, effective as a lubricant for ferrous and other metal surfaces and capable of preventing corrosion thereof in the presence of moisture and air, comprisinga light mineral oil of viscosity between 60 and seconds SUV at 100 F. containing between 0.01 and 10.0 per cent .of a substantially neutral addition product of di-cyclohexyl amine and di-(2,4- di-tertiary-butyi-phenyl) phosphate. said addition product having a'pH value of 6.8 and the proportion thereof being sufllcient to prevent rusting of ferrous metals.

G. SMITH.

TROY L. CANTRELL.