US2460301A - Lubricating oils - Google Patents

Description

Patented Feb. 1,1949

LUBRICATING QILS Bert 11. Lincoln, Ponca City, Okla", and Gordon D. Byrkit, Niagara Falls, N, Y., assignors, by mesne assignments, to The Lubrizol Development Corporation, a corporation of Delaware No Drawing. Application March so, 1945, Serial No. 585,806

12 Claims.

This invention relates broadly to lubricants. More specifically, this invention relates to materials which, when added to lubricants, greatly increase their resistance to oxidation and formation of corrosive products during use and increase their film strength and often improve other characteristics as well. This application is a continuation-in-part of our co-pending application Serial No. 461,128, filed October 7, 1942, now Patent No. 2,380,454 granted July 31, 1945, which is in turn a continuation-in-part of our application, Serial No. 323,959, filed March 14, 1940, now Patent No. 2,302,703 granted November 24, 1942, which is in turn a continuation-inpart of Serial No. 231,362, filed September 23, 1938, now abandoned; and is related to our copending application Serial No. 419,990, filed November 21, 1941, now Patent No. 2,418,358, granted April 1, 1947, which is also a continuation-in-part of Serial No. 323,959.

Present-day mechanical devices require lubricating oils of high film strength, of high oiliness characteristics, and of low tendency to oxidize during use. It has been found that the presentday hydrocarbon lubricants of the very highest quality are deficient in these very important characteristics. These three properties are of vital importance under conditions of thin film lubrication where the lubricant has been squeezed from between the friction surfaces because of high pressure, slow speeds, and other causes. It is readily seen that the viscosity or the body of the lubricant plays no part in this type of lubrication and that the remaining film of oil must have a very high film strength and be of high oiliness value to prevent rupture of the film of the lubricant, which would cause seizure. The oil film must tend to keep the coefllcient of friction as low as possible. The oil must resist oxidation when these thin films are heated in the presence of oxygen as they are in use.

Mechanical devices are being designed for higher pressure operation, and the film strength of the best quality straight hydrocarbon lubricant has been found to be too low. It will be obvious that an invention which provides a means of improving the film strength of these lubricants is of great importance to the art of lubricant manufacture and to the designer and fabricator of mechanical devices.

Substantially all machines operate in Part or at times totally under conditions of boundary or thin film lubrication, under which conditions the oiliness or unctuosity of the lubricant is the first and primary requisite of emcient operation.

Those skilled in the art of lubricant manufacture or machine manufacture will readily appreciate the value of an invention that will improve the oiliness of these otherwise high quality lubricants. Furthermore sludge and acid are especially deleterious under conditions of thin film lubrication. The sludge is not a lubricant in any sense of the word, and the soluble acid is particularly corrosive to bearing metals such as cadmium-silver, copper-lead, and the like.

In starting idle mechanical equipment which is lubricated from a sump by pumping or circulating th lubricant, there is always a short period of time in which the rubbing surfaces must operate under conditions of dry friction if'ordinary hydrocarbon lubricants are used. With dry friction, the wear on friction surfaces is extreme; and during cold weather when the lubricant is sluggish or during periods when the lubricating system'is not functioning properly for one reason or another, rubbing surfaces may not pnlys'ufler considerable wear but may be'da'm'a'ged to the point where they must be replaced. The product of our invention has a veryimportant property of reacting with the metal surfaces, penetrating or adsorbing on the metal surfaces, and leaving a film of lubricant with high oiliness character, which remains on the metal surface irrespective of the length of time the machine has been idle.

This high oiliness film gives very even and smooth operation, which may be easily discerned by the experienced operator or lubricating cants which are preeminently. satisfactory from the standpoint of oxidation in use, it is necessary to refine the oil thoroughly and then to add an inhibitor of oxidation. The thorough refining may consist of more and heavier acid treatments "or solvent treating so as to remove a considerable,

part of the oil and leave only the most stable portion. Such drastic refining is necessary in order to obtain stability with respect to' sludge formation but the oil is then subject to easy oxidation to form soluble acids and other corrosive materials. This can be prevented by the addition to the refined oil of small amounts of materials which either prevent the formation of these corrosive products or by some action render them inert. Furthermore. such well refined oils are susceptible to the formation during use of lacquer-like materials which tend to stick rings. This results in blowby and hence loss of power, failure of lubrication, scratching, scoring, overheating, and eventually replacement of parts. It is practically impossible to refine a lubricant in suchv a manner as to avoid all three of these difficulties, namely, products, and lacquer. It is considerably more advantageous to add the materials of our invention and avoid these dimculties by this method.

Many of these additive materials are effective when added to poorly refined or even wholly unrefined lubricants. The addends may thus be substituted in whole or in part for the usual refining processes.

In the prior art of applying these principles to the manufacture of lubricants, many diverse types of materials have been suggested to be added to obtain improvement in various characteristics. It has been found that the addition of various organic esters of the oxygen and sulfur acids of phosphorus frequently improves film strength, oxidation resistance, non-corrosiveness, and other characteristics. Nitrogen compounds have been found to inhibit oxidation of oils. Our materials combine both of these properties.

One object of our invention is to provide improved inhibitors of oxidation and corrosion for addition to lubricants.

Another object of our invention is to provide film strength improving addition agents suitable for use in lubricants and especially in crankcase lubricants.

Other and further objects of our invention will appear in the course of the following description.

In general, our invention comprises the addition to lubricating oils of certain organic phosphorus compounds characterized by the presence of an atom of phosphorus and an atom of nitrogen which are directly connected to each other by a double bond. The phosphorus may have a valence of 3 or 5. The phosphorus, in addition to being connected to an atom of nitrogen by means of two chemical bonds, may be directly connected to inorganic atoms such as halogen, oxygen, or sulfur, directly connected to an organic radical which may be aliphatic, carbooyclic, or heterocyclic, or connected to an organic radical through an inorganic link which may be oxygen, sulfur, or nitrogen. The pentavalent phosphorus may be connected to various combinations of these radicals. The unsatisfied valence of the nitrogen which is connected to the phosphorus by a double bond may be connected to an organic sludge, soluble corrosive radical which may be aliphatic, carbocyclic, or

heterocyclic in character or it may be connected to an inorganic radical such as nitrogen which may, in turn, be connected to an organic radical, hydrogen, or another inorganic radical such as a halogen.

In accordance with the general statement, this invention is more particularly concerned with oil soluble, halogen containing materials containing a phosphorus atom and a nitrogen atom linked together with a double bond and having the general formula: RN:P(Q) 1L where R is an organic radical containing a benzenoid ring structure; N is tri-valent nitrogen; Q is a monovalent radical which radical upon havingits valence bond satisfied with hydrogen may be vaporized; and which may be either halogen, such as chlorine, or an organic radical, such as ethyl, butyl, amyl, lauryl, etc.; cyclohexyl, methyl cyclohexyl, cyclopropyl, etc.; or naphthenyl, terpineol, etc.; and n is one or three depending upon whether the phosphorus is trior penta-valent. Thus, when Q is cyclohexyl, QI-I is cyclohexane, a compound which may be vaporized.

Another preferred type of material possessing an -N:P grouping has the general formula R-N:P(:X) (Q) where R, N and Q are as defined above, and X is an element selected from the class consisting of oxygen and sulphur. Accordingly, when oxygen or sulphur is present, the phosphorus must have a valence of five. Materials having the structure given immediately above are disclosed in our Patent 2,339,710 filed June 1, 1942, and issued January 18, 1944.

Compounds having a double bond between a phosphorus atomv and nitrogen atom have outstanding antioxidant properties. We do not know why this is true, but the characteristic resides in these compounds. We believe that the antioxidant activity is a result of the augmented chemical reactivity at the point of the double bond which is instrumental in reducing to an unusual degree the rate of oxidation and the oxidation tendencies of the fuels and lubricants with which these compounds are blended. With a double bond between the nitrogen and phosphorus atoms, there is a likelihood that these may react with primary valence bonds in an oxidation reaction, thus showing more chemical activity than when all of the valences of the nitrogen and phosphorus atoms are satisfied by primary valence bonds.

Reference may be made to the United States Patent No. 2,302,703 issued November 24, 1942, on the application of Bert H. Lincoln and Gordon D. Byrkit, Serial No. 323,959, filed March 14, 1940, now Patent No. 2,302,703 dated November 24, 1942, and reissued February 29, 1944, No. Re. 22,448, for information relative to the phosphorus-nitrogen compounds having a double valence bond between the nitrogen and phosphorus.

The halogen-bearing organic nitrogen compounds wherein the nitrogen and phosphorus are connected by a double bond are particularly effective addition agents for lubricating oils and fuels. These halogen-bearing compounds, have the ability to produce the salutary effect of greatly increasing the film strength of the lubricant containing the compound as an addition agent of the organic phosphorus-nitrogen compounds described in Patent No. 2,302,703 but which compound does not contain halogen. In addition to the marked increase in the film strength of oil containing a halogen-bearing addition agent as herein described, as compared to the unblended oil and nonhalogen containing oil, the coeflicient of friction of an oil into which has been incorporated a small quantity of halogen-containing organic phosphorus-nitrogen compound is appreciably less than the same oil containing a like amount of a halogen-free organic phosphorusnitrogen compound. We believe this improvement is due to the polarity of the compound containing the halogen. Our theory is that the active halogen atom or atoms chemically activate the organic phosphorus-nitrogen compound in such a manner that the halogen-bearing molecules are induced to annex themselves on and near the surface of the metallic parts which they contact to form upon such metallic parts a protective regimented film of multimolecular dimensions which is extraordinarily effective in resisting extreme pressures. This theory is in part substantiated by the fact that these additives enable a lubricant to satisfactorily lubricate under nonfluid conditions and under boundary lubrication conditions. 7

The halogen may be present in the compound in any one or in combinations of its forms. One or more atoms of bromine, fluorine, iodine, chlorine, or combinations of these elements may be compound may be residual halogen remaining in the product after preparation or it may be introduced subsequent to the preparation of the organic phosphorus-nitrogencompound in a separate and distinct halogenation reaction or it may be present in the compound due to both causes.

In connection with this invention, the teaching in our United States patent application Serial No. 419,990, filed November 21, 1941, should be noted. There the beneficial eirect of combined sulfur is disclosed. We there disclose in general that organic phosphorus-nitrogen compounds having a double bond between the phosphorus and nitrogen atoms may be rendered more effective oxidation and corrosion inhibitors by the presence of sulfur in the organic phosphorus-nitrogen compound.. These compounds containing 1 both halogen and sulfur are particularly eflective addition agents because the lubricant exhibits great film strength, high oiliness, antioxidant, and anticorrosive properties.

Some of these materials which are suitable for use in accordance with our invention are shown in the following outline. All and each of these are to be considered as examples of our invention when blended in an oil of lubricating viscosity.

A. Sulfophosphazoaryl halides, RN:PSX (R is an aromatic radical and X is a halogen) -1. Sulfophosphazobenzene chloride CaH5N:PSCl 2. Sulfophosphazomethylbenzoate ride, CH30.CO.C6H4N2PSC1 3. Sulfophosphazochloronaphthalene chloride ClCroHsNtPSCl B. Phosphazo halides, R--N:PX (R is an aromatic radical; X is a halogen) 4'. Phosphazobenzene chloride ceHsNzPcl 5. Phosphazoxylene chloride (CH3)zCeI-I3N:PCI

6. Phosphazochlorobenzene chloride C1CsH4NIPC1 7. Phosphazophenyl benzene bromide,

CtHsCsHeN 1 P31 8. Phosphazonitrobenzene bromide,

C. Oxyphosphazo-aryl anilides RNH.PO:NR' (R and R are aromatic radicals at least one of which contains halogen) v 9. Oxyphosphazobenzochloroanilide ClCeH4NH.P0:NCsHs D. Trichlorophosphanils, RNzPCls 10. Trichlorophosphanil, CoHsN2PCla 11. Trichlorophosphochloranil,

C1CsH4N :PCls

chlo- 6 f i I E. Aryl phosphin-imlnes, RaPiNR' (R' is. aromatic; B may be aromatic or aliphatic, at least one of the radicals contains halogen) 12. Tribenzyl o-chlorophenylphosphinimine, (CsI-IaCHa) 3P NCBHiCl Any of these compounds or other members of the classes in the above list or their derivatives or any other compound within the limitations set forth in the generic description of this invention may be used and such use is contemplated as within the scope of this invention.

The compounds of group A of this invention may be made, for example, by reacting an amine which may or may not contain a halogen or an amine derivative which may or may not contain a halogen with (PSCls) thiophosphoryl chloride. The two hydrogen atoms on the amine nitrogen are removed with two chlorine atoms from the PSCla, thus giving the nitrogen phosphorus double bond. The compound will contain residual chlorine because an atom of chlorine, will remain in the radical representing the thiophosphoryl chloride and may contain halogen because of the presence of an amount of chlorine in the amine or amine derivative. The organic radical attached to the amine or amine-derivative may be either open chain or closed chain with only carbon or with carbon and other elements, such as nitrogen, sulfur, and'the like. If the organic radical is a closed chain of the aromatic type, various substituents may be placed on the ring. For example, long-chain aliphatic radicals, like petroleum wax, may be substituted. Other organic radicals containing,characteristic groups may also be substituted; therefore amines of waxylated benzene, naphthalene, cyclohexane, and the like may be reacted with PSCla. Chemically saturated and unsaturated aliphatic amines may be employed in making the product of our invention. For example, alkyl amineor sulfurized or chlorinated alkyl amine may be employed. Hexyl amine and cyclohexyl amine, chlorinated or brominated hexyl amine and cyclohexyl amine, when reacted with PSCla, give products usable in our invention.

It is to be understood that in practicing our invention, oil-soluble halogen-containing phosphorus-nitrogen compounds of the type described are to be selected. Some of the compounds within the scope of the broad definition of the compounds of use in the practice of this invention have only limited solubility'in hydrocarbon oils. It is to be remembered, however, that because of their great efliciency, extremely small amounts are often effective. Thus we may use as little as 0.001 per cent of some of these compounds, and it will be seen that a fairly insoluble material may dissolve to a suflicien't extent to be satisfactory for our purpose. While certain specific examples of the broad class of halogen-nitrogenphosphorus compounds defined above may not be extensively oil soluble, only those which are soluble to the extent of at least 0.001% are con- Y the hydrocarbon oil is the use of a mutual solvent to bring the addend into solution. Alternatively, peptizing agents may be addedto maintain the organo-phosphorus-nitrogen compound in permanent suspension.

Many of the more diflicultly soluble materials are rendered more soluble by the introduction of alkyl groups, particularly those containing four or more carbon atoms. The isoamyl, octyl, lauryl, and octadecyl radicals and radicals from paraflin wax greatly increase the solubility of organic compounds in oil. One or more of such groups may be introduced as required into the previously described compounds or their derivatives.

In the selection of a particular compound or compounds to be used as an addition agent to the hydrocarbon oil, consideration should be given to the uses for which the blend is designed. Thus, if water is likely to be present during use, a phosphorus compound or combination of compounds is selected which is not affected by water. In general, We prefer to use compounds having boiling points over 250 F. It is sometimes advantageous to combine more than one of these compounds in a blend to obtain particular properties. We accomplish this by mixing two or more of these compounds together and blending the mixture with the hydrocarbon oil or by blending one in the hydrocarbon oil, blending the second into this mixture, and so on until the composition is complete.

The various halogen-phosphorus-nitrogen compounds improve both the film strength, oxidation characteristics, and the sludging characteristics of the hydrocarbon oil. For example, the sludging tendencies may be decreased by as little as 0.001 per cent of our halogen-phosphorus-nitrogen compounds. The oxidation characteristics of lubricants are very important, and these are markedly improved by our compounds. The ability to reduce friction is another feature contributed to lubricants by our halogen-phosphorusnitrogen compounds.

It may be desirable to include in one and the same blend based on a hydrocarbon oil, in addition to the addends here described, other addends for specific purposes. Thus, we may add a pour point depressor such as a naphthalene-chlor wax condensation product and a viscosity index improver such as certain resins or polymerized hydrocarbons in addition to our halogen-containing organo-phosphorus compounds. Furthermore, various metallic compounds may be added to the blend without interfering with the action of our ingredients. Indeed, in some cases it is advantageous to combine with our organic halogenbearing phosphorus-nitrogen compounds in a hydrocarbon oil blend such materials as calcium dichlorostearate, chromium oleate, tin octadecyl phthalate, aluminum stearate, and other metallic soaps.

Our addends are admirably adapted for use in lubricating oils of all types including those designed for use in automotive crankcases, Diesel oils, and any other oils of lubricating viscosity such as castor oil, cottonseed oil, lard oil, sperm oil, shale oil. Furthermore, our addends are advantageously blended in gasoline and other petroleum fuels either directly or after being blended first in a lubricating oil and then added to the fuel. Soap-thickened mineral oils of all types ranging from those showing only a slight increase in viscosity over that of the mineral oil alone to the semisolid and solid greases containing fifty per cent or more of soap are amenable to treatment according to our invention. In making these greases, the usual soaps such as sodium stearate, aluminum stearate, calcium soaps of beta fat and the like may be used. Various other thickening ingredients or materials for other purposes may be added. These include yarn, hair, graphite, glycerol, water, lamp black, mica, zinc dust, litharge, and the like.

The following examples of blends of our addition agents are given as illustrations but not as limitations:

In making a lubricating gasoline, we blend 0.5 per cent of the product of Example 1 with gasoline. The product has the composition:

Per cent Gasoline 99.5 Oil .495 Sul-fophosphazobenzene chloride .005

It is to be understood, however, that the hydrocarbon oil in the treated fuels may be of a viscosity of from about 35 seconds at 100 F. S. S. U. to 350 seconds or more; and the amount of oil blended with the halogen-phosphorus-nitrogen compound to form the fuel addend may vary between 0 per cent and 99.5 per cent. In some cases the fuel may be prepared without adding any hydrocarbon oil. The quantity of halogen-sulphur-phosphorus-nitrogen compound in the final blended fuel may vary from 0.0001 to 1.0 per cent or slightly more.

It will be understood that certain features and sub-combinations may be employed without reference to other species or combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is therefore to be understood that our invention is not to be limited to the details described.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We therefore particularly point out and distinctly claim as our invention:

1. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion sufiicient to stabilize the oil against oxidation of an oil-soluble halogen-containing organic phosphorus compound having the general formula R-N:P(Q) where R is an organic radical containing a benzenoid ring structure; N is trivalent nitrogen; Q is a halogen radical, and n is a small whole number selected from the numerical group consisting of the numbers 1 and three.

2. A lubricant in accordance with wherein Q is chlorine.

3. A lubricant in accordance with wherein Q is a hologen and n is one.

4. A lubricant in accordance with wherein Q is chlorine and n is one.

5. A lubricant in accordance with wherein Q is a halogen and n is three.

6. A lubricant in accordance with claim 1 claim 1 claim 1 claim 1 claim 1 wherein Q is chlorine and n is three.

7. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion from about .001% to about 5% by weight of the final lubricant blend of trichlorophosphanil,

8. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion from about .001% to about 5% by weight of the final lubricant blend of phosphazo benzene chloride.

9. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion from about .001% to about 5% by weight of the final lubricant blend of phosphazochlorobenzene chloride.

10. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion from about .001% to REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,448 Lincoln et al. Feb. 29, 1944 2,109,490 Lipkin Mar. 1, 1938 2,146,584 Lipkin Feb. '7, 1939 2,279,218 Badertscher Apr. '7, 1942 2,302,703 Lincoln et al. Nov. 24, 1942 2,339,710 Lincoln et a1 Jan. 18, 1944