US2339710A - Lubricant - Google Patents

Description

Patented Jan. 18, 1944 LUBRICANT Bert H. Lincoln, Ponca City, Okla., and Gordon D. Byrkit, Niagara Falls, N. Y., assignors to Continental Oil Company, Ponca City, Okla., a

corporation of Delaware No Drawing. Application June 1, 1942, Serial No. 445,376

9 Claims. (01. 252-48) This invention relates broadly to improvements in lubricants and more specifically to improved materials which, when added to lubricants, great- 1y increase their resistance to oxidation and formation of corrosive products during use and often improves other characteristics as well.

The application is a continuation-in-part of our coepending application, Serial No. 323,959,

filed March 14, 1940, which matured into Patent No. 2,302,703, dated November 24, 1942, which is a continuation-impart of Serial No. 231,362, filed September 23, 1938.

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 andthat the remaining film of oil must have a very high iilm strength and be of high oiliness value to prevent rupture of the film of the lubricant, which would cause seizure. oil film must tend to keep the coefilcient'of friction as low as possible. The oil must resist onidation when these thin films are heatedin the presence of oxygen as they are in-use.

Mechanical devices are being designed for higher pressure operation, and th 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 manu facture 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 requiste of emcient operation.

The

ticularly corrosive to bearing metals such as cadmium-silver, copper-lead, and the like.

In starting idle mechanical equipment which is lubricated from a sump bypumping or circulating the lubricant, there is always a short period of time in which the rubbing surfaces must operate under conditions of dry friction if ordinary hydrocarbon lubricant 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'lubricatingsystem is'not functioning properly for on reason or another, rubbing surfaces may not onlysuifer considerable wear but may be damaged to the point where they must be replaced. The product of our invention has a very important 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 metalsurface 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 engineer.

When the hydrocarbon lubricants are diluted with unburned fuel or with other light hydro- 1 carbons, the small degree of oiliness of the original hydrocarbon lubricant is greatly decreased. We have found that theadditionof th products ofour invention to hydrocarbon lubricants more than compensates for the loss in oiliness and load-carrying ability from dilution.

It is well known that, in order to obtain lubricants 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 solubleacids and other corrosive materials. This can beprevented by the addition to the refined 011 of small amounts of materials which either prevent the formation of these corrosive products'or by some action render them inert. ermore. ouch well refined oils are susceptible to the of lacquer-like materials which tend to rings.

This results in blowby and hence loss of power,

failure of lubrication, scratching, scoring, overtion during use heating, and eventually replacement of parts. It is practically impossible to refine a lubricant in such a manner as to avoid all three of these difficulties, namely, sludge, soluble corrosiv products, and lacquer. It is considerably more advantageous to add the materials of our invention and avoid these difficulties 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 interpreted as broadly as the prior art permits.

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, noncorrosiveness,

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 consists of the addition of certain organic phosphorus compounds containing at least one phosphorus-nitrogen double bond and at least one atom of sulfur chemically combined with the organic phosphorus compound to hydrocarbon fuels and lubricants. These materials have the advantages of the phosphorus compounds and of the nitrogen com-- 7 pounds, particularly in preventing the development of corrosive materials during use and are rendered more efiective, particularly in respect to prevention of the formation of or continued presence of deleterious oxidation catalysts which are readily formed in the crankcase lubricants of'internal combustion engines, by the presence of sulfur. Compounds having a double bond between aphosphorus and a nitrogen atom have outstanding antioxidant properties. Why this is so is not clear, but the fact remains that it is so. 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 oxidation rate and oxidation tendencies .of the fuels and lubricants with which these compounds are blended. With a'dcuble 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. The sulfur in the molecule is believed to be eifective because it acts upon the metals contacted by the lubricant and which normally promote and accelerate oxidation and deterioration of a hydrocarbon oil. The metals, or metalliccompounds, whether dissolved in the oil or present in small particlesin the'oil, are rendered inert or less catalytically active by the sulfur in the additive we add to the lubricant. Furthermore, another beneficial effect that the sulfur has, especially if the sulfur is rather unstably bound into the molecule in Besides the unexpected and unusual oxidation inhibiting effects produced by this class of compounds, there is increased film strength and increased oiliness. Some of these materials which are suitable for use in accordance withour invention are shown in the following list. All and each of these are to be considered as examples of our invention when blended in an oil of lubricating viscosity.

1. Sulfophosphasobenzene chloride,

CcHsN :PSCl

2. Sulfophosphazomethylbenzoate chloride,

CHaQCQCaI-hNtPSCl 3. Sulfophosphazochloronaphthalene chloride,

ClCmI-IomPSCl Any of these compounds or other members of the classes represented or their derivatives within the limitations set forth above may be used I within the scope of our invention.

The compounds of this invention may be made, for example, by'reacting an amine or an amine derivative with (PSCls) thiophosphoryl chloride. The two hydrogen atoms on the amine nitrogen are removed with two chlorine atoms from the PSCls, thus giving the nitrogen phosphorous doubl bond. The organic radical attached to the ne or amine derivative may be either open chain or closed chain compounds with only carbon or with carbon and other elements, such as nitrogen, sulfur, and the like. If the organic radical is closed chain 'and 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 PSCls. Chemically saturated and unsaturated aliphatic amines may be employed in making the products of our invention. For example, alkyl amine or sulfurized or chlorinatedalkyl amine maybe em ployed. Hexyl amine and cyclohexyl mine, when reacted with PSCla, give products usable in our invention.

It is to be understood that in practicing our invention, oil-soluble sulfur-containing phosphorus-nitrogen compounds of the type described are to be selected. Some of the compounds within the scope of the broad definition oi' 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 emciency, extremely small amounts are often eflective. 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 sufilcient extent to be I ing a givenmaterial. For some purposes therefore, we prefer paramnic lubricants, while for other purposes we prefer naphthenic or mixed base lubricants. Another method of obtaining a satisfactory mixture or addition agent with the ydrocarbon oil is the use of a mutual solvent to bring the addend into solution. Alternatively,

peptizing agents may be added to maintain the wax greatly increase the solubility of organic compounds inoil. One or more or such groups may be introduced as required into the previously described compounds or their derivatives.

The selection or a particular compound or compounds to be used as an addition agent to the hydrocarbon oil is to be made considering the use to which the blend is put. 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 mixture, and so on until the composition is complete.-

The various phosphorus-nitrogen compounds usually improve both the film strength and oxidation characteristics of the hydrocarbon 011.

For example, the sludging tendencies may be dephorus-nitrogen 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 naphthalenechlor wax condensation product and a viscosity index improver such as certain resins or polymerized hydrocarbons in addition to our organo-phosphorus com ounds. 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 phosphorus-nitrogen compounds in a hydrocarbon oil blend such materials as calcium dischlorostearate, chromium oleate, tin octadecyl phthalate, aluminum stearate, and other metallic soaps.

Our addencls are admirably adapted for use in lubricating oils of all types including those de- I limitations:

Example 1 Per cent lldid-Continentparafiin-base SAE 30 99h Sulfophosphasobenzene chloride..- 1.0

Example 2 g Per cent Mid-Lontinent mixed base SAE 50 88.5 Aluminum naphthenate Hi Sulfophosphazomethylbenzoate chlorida--- 1.5 Y

Example 3 the hydrocarbon oil, blending the second into this signed 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 011. Furthermore, our addends are advantageously blended in gasoline and other petroleum fuels either directly or after being blended first in a. lubricating ofl and then added to the fuel. Soap-thickened mineral oils of all types ranging from those showing only a slight increase in viscosityover that of the'minerai 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 soapssuch as sodium stearate, aluminum stearate, calcium Scene of beta fat and the like may be used. Various other thickening ingredientsor 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 asillustrations but not as In making a lubricating gasoline, we blend 6.5 per cent of the product oi Example 1 with gasoline. The product has the composition:

. Per cent Gasoline 99.5 Oil .495 Sulfophosphasobenzene 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 F. S. S.

to 350 seconds or more; and the amount of oil blended with the phosphorus-nitrogen compound to formrthe fuel addend may vary between 0 per cent and 99.5 per cent. In some casesthe fuel may be prepared without adding any hydrocarbon oil. The quantity of sulfur-containing phosphorus-nitr'ogen compound in the final blended fuel may vary from 0.001 to 1.0 per cent or slightly more.

It will be understood that certain features and subcombinations may be employed without reference to other species or combinations. This is contemplated by andls within the scope of our 2. Av lubricant comprising in combination a major proportion of oil of lubricating viscosity and a minor proportion of an organic compound containing phosphorus and nitrogen connected by a double bond. and being further characterized by the presence of at least one sulfur atom in the organic phosphorus compound.

. 3. A lubricant comprising in combination oil of lubricating viscosity and from 0.001 to 5 per cent of an organic phosphorus compound containing at least one nitrogen-phosphorus double bondhaving at least one atom of sulfur in the organic phosphorus compound.

4. A lubricant comprising in combination -a major proportion of oil oi lubricating viscosity and a minor proportion of a sulfophosphasoaryl chloride.

5. A lubricant comprising in combination a major proportion of oil of lubricating viscosity and a minor proportion of sulfophosphasobenzene chloride.

6.- A lubricant comprising in combination a major proportion of oil of lubricating viscosity and a minor proportion of sulfophosphasomethylbenzoate chloride.

7. A lubricant comprising in combination a major proportion of oil 01' lubricatingviscosity' and a minor proportion of sulfophosphasochloronaphthalene chloride.

phorus compound.

BERT E. LINCOIN. GORDON D. BYRKIT.