US2394954A - Lubricant - Google Patents

Description

Patented Feb. 12, 1945 LUBRICANT Walter 'r. Watkins, In, Elizabeth, N. J., assignor to Standard Oil Development Company, a'cor poratlon of Delaware No Drawing. Application December 20, 1940, Serial No. 370,961

12 Claims.

The present invention relates to improvements in lubricants and especially to the improvement of lubricating oils principally useful for internal combustion engines operating under severe conditions. The invention will be fully understood from the following description.

Lubricating oils which exhibit improved performances under all types of operating conditions when used for the lubrication of heavy dutygasoline engines and for Diesel engines are coming.

into greater and greater demand. The requirements for such. oils are being steadily made more stringent and it has been proposed to add various ingredients to these oils to improve-their behavior in such service. The main purpos of these ingredients is to bring about greater engine cleanliness and to avoid ring sticking, varnish formation and carbon deposition. Some of the materials proposed for this-service are excellent in one or more respects but are'found to be unfavorable in other respects; for' example, some of the com,- pounding agents are found to be corrosive to bearings, especially the newer type alloys of sflver and cadmium and of copper and lead.

The addition agents which form the basis of the present invention are the oil soluble salts of xanthie acids. These acids have the following general formula:

where H is a hydrogen atom replaceable by metal and where R is an alkyl radical such as CrHs, CaH'l,

etc., or a higher radical of the same general type such as CuHzs or CmHsv, or a cycloalkyl or aralkyl radical such as cyclohexyl or benzyl. Also, these radicals may contain sulmtituent groups such as halogen, Sulfur, phosphorus, nitro, amino, hy-

droxyl, and the like.

One method of preparing these salts is by reacting carbon disulflde with the alcohol corresponding to the particular radical R, in the presence of a strong alkali such as caustic potash. The potassium salt thus formed can be reacted with a suitable inorganic salt to produce the desired compound by double decomposition. Thus,

for example, nickel amyl xanthate was prepared method of preparing these compounds, the methods being given forthe purpose of example only. I

The metal salts of the xanthic acids-which are used in the present invention, comprise the class of the oil soluble salts of metals of the 1st, 2nd, 3rd, 4th, 6th and 8th groups of the periodic table of elements. In addition to metallic salts, the salts of other salt forming radicals ma be employed similarly. Thus, the xanthic acid salts of ammonia, of quaternary ammonium bases, of sulphonium and phosphonium bases, of pyridine, amines and the like may be used. These various salts are not strict equivalents, in the sense that some are particularly useful for certain operations and others for other conditions, but among the most important metals are lithium, sodium, potassium, aluminum, chromium, tin, the metals of the 2nd group, in particular zinc, calcium, barium, cadmium and magnesium, and the metals of the 8th group, particularly nickel and cobalt.

The alcohols from which the xanthic acid salts are prepared must be so chosen as to provide 'a final product possessed of the desired oil solubility. While the nickel salts of even ethyl xanthic acid are fairly oil soluble, xanthic acids prepared from higher alcohols are required for the otherpreparations, as for instance, the calcium and barium compounds, if these are to possess adequate solubility in the base oil. Salts of xanthic acids prepared from suitable polyhydric alcohols are also contemplated. Different oils exert different powers of solution but solubility may also be improved by the inclusion of mutual solvents such as chlorinated hydrocarbons, higher alcohols, higher acids, esters, phenols, and the like,

The above mentioned salts are added to the oil in proportion from about 0.10 to 4 or 5%. If

desired, single metal salts of a single xanthic acid may be used, but singlesalts of mixed acids,

prepared from mixed alcohols, are also contemplated. Furthermore, if it is desired, salts of mixed metals may be employed, for example, magnesium and barium or other metals of the groups listed above.

More broadly the compounds employed in the present invention may be represented by the general formula:

R-O- -s-M-'r.

in which R is an alkyl, cycloalkyl or aralkyl nium, ammoniump'suifonium, and the like); T may also be RFO-C'(S)S or other group capable of linking with M, such as: alcohol, thio- I alcohol, ,acid, phenol, thiophenol, phenolsulfide; and n is an integer whose value is chosen to satisfy valence requirements. When M is monovalent, n is obviously 0.

Other examples of xanthate salts which may 7 be employed in this invention include the followorder to give the oils greater load carrying capacity, or even extreme pressure properties, but the present compounds are fairly efiective as load carrying agents and one of their particular virtues is the fact that they are non-corrosive to the present bearing alloys as well as to copper, brass and the like. It is found desirable, however, in many cases to add small amounts of a higher alcohol or carboxylic acid to these oils, particularly when they are employed for the lubricaticn of Diesel engines. For this purpose,

xanthate, zinc cyclohexyl xanthate, cobalt amyl xanthate, calcium chlorocetyl xanthate, calcium benzyl xanthate, aluminum butyl xanthate, barium ethyl amyl xanthate and magnesiumcalcium decyl, xanthate. It is not intended that the invention be limited to the compounds listed, which are given merely for the purpose of illustration.

The hydrocarbon oils used may be straightmineral lubricating oils or distillates derived from paraffinic, naphthenic or mixed base crudes or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay, or they may be extracted oils produced, for example, by solvent extraction with solvents of thetype of phenol, sulfur dioxide, furfural and the like. Hydrogenated oils may be employed as well as synthetic oils prepared, for example, by the condensation of olefins or reaction of carbon oxides with hydrogen. The lubricating oils, how'- ever they'may.have been produced, may vary considerably in viscosity and other'properties, depending on the particular use for which they are desired, but they usually range from about 40 to 150 seconds Sabolt at 210 F. The oils may be free from other addition agents or they may contain other materials for particular purposes. For example, thickeners such as polyisobutylene may be added, as well as esters, to increase oiliness. Sludge dispersing agents, dyes, pour depressants and anti-oxidants may also be employed for their particular purposes without departing from the present invention. Additional sulfur or chlorine containing compounds may be added in the amount of alcohol or acid may be less than about 1%. v

It has also been found desirable in some cases to add these metallic xanthates to lubricating oil blends containing other metallic addition agents such as metallicphenolates, metallic phenol sulfides, metallic alcoholates, metal soaps and the like, the metallic xanthate and the other metallic compound exerting mutual assistance in improving the performance characteristics of the lubricating composition.

The following examples may be considered to illustrate the nature and the effects of the present agents:

Example 1 To a sample of well refined lubricating oil, SAE 40 grade, was added /4% of a nickel salt of ethyl xanthic acid which has the followin formula:

This sample and also the oil which did not contain the nickel xanthate were then run under identical and carefully controlled conditions in a C. l. R. engine for 14 hour periods while maintzgining the cooling jacket at a temperature of 3 0 F.

After each test the engine was taken down and the piston assemblies carefully examined. Each part, that is rings, grooves, Skirt and the like, was rated according to its condition. From these separate ratings an over-all rating was determined by a system of weighting the ratings of the separate parts so as to take into account each factor. The data on the two runs are given in the following table:

Rings stack 1 on Over Ring Ring Bkirt all slits grooves varnish No. Degrees SAE 40 oil........ 5. 20 3 810 7. 17 6. 5 6.0 Oil-+0.25% Ni.

ethyl xanthate- 1.48 0 0 1. 67 3.8 V 0.25

Example 2 A blend of 0.5% of nickel amyl xanthate was prepared in a naphthenic base lubricating oil having a viscosity of about 55 Saybolt seconds at 210 F. This oil blend was tested for 60 hours in a Caterpillar Diesel engine under high-temperature conditions (210 F. oil; F. atmosphere) and its erformance was compared with that of the naphthenic oil alone under the same conditions and for the same length of time. After each test the various parts of the engine .were examined and given demerit ratings. The data obtained are presented below. It should be borne in mind that the higher the figure given the worse the condition observed. It will be seen-that the blend containing nickel amyl xanthate was deflnitely better than the naphthenic oil alone.

. Copper-lead on Overall Egg on mm bearing demerit demem demerit weight loss,

. grams Naphthenic oi1.. l. 91 2. 93 5. 0.014 Naphthenic oil Ni amyl xanthate 1. 37 86 3. 00 0. 004

I claim:

where R is an alkyl radical of less than 20 carbon atoms.

- 4. Product according to claim 3 inwhich the metal salt is. a salt of a metal of the 8th group.

5. Product according to claim 3 in which the metal salt is a nickel salt.

- 6. Product according to claim 3 in which the metal salt is nickel amyl xanthate.

7. Product according to claim 3 in which the salt is a salt of a metal of the 2nd group.

8. Product according to claim 2 in which the metal salt is a calcium xanthate.

9. Product according to claim 2 .in which the metal salt is an aluminum xanthate.

'10. The method of cleansing and lubricating automotive engines which consists in charging to said engines a lubricant comprising a mineral hydrocarbon oil having incorporated therein a salt or an alkyl xanthic acid, the alkyl radical of which contains less than 20 carbon atoms, in amount and potency suflicient to obviate the formation ofvarnish and sludge deposits and to remove anysuch deposits already present.

1'1. Method of cleansing and lubricating engines according to claim 10 in which the salt of a muthic acid is a nickel salt of an acid having the following formula:

where R. is an alkyl radical of less than 20 carbon nickel amyl xanthate.

WALTER 'r. WATKINS, JR.