US2252087A - Lubricant - Google Patents

Description

Patented Au 12, 1941 LUBRICANT John G. McNab, Roselle, and Walter 'r. Watkins, Jr., Elizabeth, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application September 20. 1938,

Serial No. 230,782 Claims. (Cl, 252-37) The present invention relates to an improved lubricant, and particularly a. fluid lubricating oil of the type "containing metallic soaps and an improved methodof making the same. These oils are particularly useful in the lubrication of automotive machinery such as Diesel engines and automobile engines, but they'are likewise useful.

in the manufacture of various process oils, castor machine oils, and the like. For many years various metal soaps have been added to mineral lubricating pils to give superior lubricating properties, but there have been various objections to these compositions for Diesel and automobile engine lubrication and their use hasonly recently spread into this field. In some instances the soaps have been found to be lnsoluble and therefore useless. In other cases, a degree of solubility appears to be attained, but intime the soap is foundto gel or to settle from the oil. When applying these lubricants to use under high temperature conditions, it is found that many of them are undesirable because of tendency to form sludge and carbonaceous deposits.

It has been recently found that these difliculties can be overcome first by a proper selection of the soaps, using on the one hand a proper metallic base, and on the other, proper soap acids and, secondly, by separating from these materials the non-saponaceous impurities. 1

For the present invention the most important soaps are those of calcium, magnesium, barium,

1 zinc, copper, aluminum, the metals of the fourth group, particularly germanium, tin and lead, soaps of manganese and chromium, and the metal.

soaps of the iron group, namely iron, cobalt and nickel. The soaps of metals of the second to the eighth groups show this improvement to a greater or less degree which has not been found-in the stronger alkali metal soaps.

In making the soaps for the present compositions it has been found that the straight chain saturated fatty acids such as stearlc, margaric, palmitic, are not desirable because they are too high in melting point, and thesoaps are too in-. soluble for, best results, although theymay be used if mixed with the. more satisfactory type of acids mentioned below. The broad class of acids which is the most satisfactory is the class of the aliphatic organicacids or substituted aliphatic acids having at least 10 to 12 carbon atoms and melting points below about 50 C. Among the most satisfactory acids of this general class are the unsaturated fatty acids of the type of oleic acid, the naphthenic acids which are obtained from certain crude oils,'especially those from Roumania, Texas, and other. fields, the mixed saturated and unsaturated acids produced by the air oxidation of petroleum products such as waxes or mineral oils,but especially from liquid hydrocarbons sweated from, crude solid 'waxyhydrocarbons, at temperatures from say to C. in-the presence of catalysts such as barium and magnesium soaps, the modified saturated aliphat- 1c. acids :containing solubilizing substituent groups, for example, aromaticsubstituted radicals such as in phenyl or naphthyl stearic acids or cresyl margaric acid, and the like. Other types of acids which can be used, are the acetylated hydroxy acids, for example, acetylated hydroxy stearic acid, made. by-the reaction of an organic acid halide with a suitable hydroxy acid, but it will be understood that various acid chlorides such as stearyl chloride and the like may be employed. 'The etheriiied hydroxy acids may also be employed, using the lower or higher molecular weight acids, ranging from .methyl or'ethyl to stearyl or oleyl alcohol, to etherify the hydroxy acid. Ketonized acids may also be used as well as simple halogenated fattyacids, for example dichlorstearic andthe like, as well asrosin acids such as abietic or hydrogenated abietic acid. Mixed acids are also extremely useful.

The above mentioned metal soaps of these various acids have been found to be greatly improved by removal of non-saponaceous impurities. The

soap may be made by double decomposition of an of aluminum chloride or sulfate with sodium naphthenate, and other soaps in an analogous manner. Free acid and non-saponaceous impurities are then removed from the soap in any convenient manner.

The removal of such impurities may be effected most satisfactorily by extraction with a suitable organic solvent in which the said impurities are soluble and in which the soap is not. As solvents, low molecular weight oxygen-containing organic compounds are most useful, particularly the alcohols such as methyl, ethyl, the various propyl and butyl and the like, as well as ketones such as acetone, diethyl and methyl ethyl ketone. Various mixtures of the above mentioned materials may be employed, or mixtures of these substances. Chlorinated aliphatic or aromatic hydrocarbon solvents-may be used such as ethylene dichloride, di, tri or tetra chlorethane. Repeated extraction or oountercurrent extraction may be employed so as to produce a highly purified soap but if sumcient solvent is used a single extraction is usually sufllcient. It will be understood that it i not necessary to remove all traces of the impurities or non-saponaceous material, but the soap appears to be improved to the'degree in which these substances are removed.

The purified soap is then added to a suitable mineral lubricating oil to produce the finished lubricant. The type of oil and the amount of soap, vary with the particular use of the lubri- .cant. For some purposes the amount of the soap will vary from say A to 2 percent. Insuch concentrations the soap does not materially increase the viscosity of the oil, for example, usually less than about of the Saybolt viscosity as measured at 100 F. Such amounts of soap are highly satisfactory in producing lubricants for automotive machinery, especially Diesel engines; but larger amounts of soap may be employed where a considerable thickening or increase in viscosity is desired. Such compositions may contain, for example, as much as 10 to 20% of the soap oreven more and the viscosity will begreatly increased over that of the original oil.

The oil used for producing Diesel and other automotive lubricants is preferably a naphthenic distillate oil of low cold test, but paraflinic oils may be used for this purpose, and are preferred for many uses. In any case the soaps produced are especially useful in producing lubricants for hypoid and other high pressure gears, and they are to be employed in connection with corrosive sulfur compounds.

The present composition may also contain other ingredients such as dyes for imparting color, oiliness agents such as the stable esters of monohydric alcohols with saturated acids having more than 10 or 12 carbon atoms such as stearic, and esters of phosphorus acids such as tricresyl phosphate or phosphite. or similar aliphatic esters. The compositions may contain pour point depressants if wax is present, preferably of the type prepared by condensing aromatic compounds, hydrocarbons, phenols or other ring compounds with chlorinated paraflin wax. Thickening agents such as olefin polymers especially those polymers of iso-olefins like isobutylene, which have molecular' weights above 1000 but preferably much higher. Sludge dispersers and anti-oxidants may be added also, especially sulphur compounds such and purified by the method disclosed above form The present invention would be better understood by consideration of the following examples:

Example 1 The aluminum soap of synthetic fatty acids obtained by the oxidation of oil sweated from wax was prepared by adding an aqueous solution of the sodium soap to an agitated aluminum sulfate solution. The resulting aluminum soap was disly desirable because of their decreased tendency most severe usage.

It has been found, as stated above, that while the acids preferred for producing the heavy soaps should not be allowed to remain in excess of that combined with the metallic element, certain other free acids may be added with advantage. For this purpose it is preferred to use saturated fatty acids of the type of stearic and margaric. Such 'acids may have melting, points above C. although this is not required, the amount used being such as not to greatlly raise the pour point of the composition, for example, in the total oil, there may be from M; to 1 or 1 /2% of free saturated fatty acid. When present this acid actually improves the oil, although when used in making the soap it is distinctly undesirable. In this manner it will be noted that the purification step is employed to remove nonsaponaceous materials associated with or derived from the acids preferred for making the metal soaps and the acids which are added to thepurified soaps are of a type or class which isundesirable for making the said soaps.

The oil compositions disclosed above may be used for various purposes and the different soaps differ and cannot be considered as exact equivalents for all purposes although the process of preparing them is the same. The soaps of aluminum, calcium and nickel are preferred in the manufacture of Diesel and automotive lubricants, but the remaining metal soaps are useful for this I pared by extraction of the above aluminum soap with isopropyl alcohol so as to remove free acid and other non-saponaceous impurities. The exand other purposes. Lead and tin andzino soaps traction was carried out by agitating the unpurified. aluminum soap with five volumes of 91% isopropyl alcohol at a temperature of F. The extracted soap, free of organic acids and jlactones was separated by filtration and dissolved in a naphthenic base stock in concentration sufficient to yield a 0.10% ash on the finished oil. This sample is designated B. v

A further improved oil blend was prepared by adding'stearic acid (0.5%) to the compounded oil containing the purified (alcohol extracted) aluminum soap mentioned above. Sample C.

The above samples were then tested in a single cylinder caterpillar Diesel engine and at the conclusion of each test the engine was taken down and the piston 'was carefully examined. Each part of the piston was given a demerit rating depending on its condition, wear, cleanliness, presence of gummy or carbonaceous deposits being taken into consideration. Then the rating of the engine was obtained by a system of correlation in which the relative importance of each demerit is given weight. These data are inserted very superior to those with A and B, and at 1000.

. 3 I the present example. This sample, designated Unextracted, contained free acid as well as 23,252,087 hours the results with C are in almost every instance better than those with A at 480'hours, and

almost the equal of B at 500.

associated non-saponaceous impurities.

Tania I Caterpillar Single Cylinder Engine Tests Liner wear Demerits n per 1000 hours '1 -1 H itfii 1 samp es ours p s on demerit Ring Rmg cleanliness Skirt Varnish on hrsJ edge Carbon an on filter. gallon Max. Ave. sha'p Slits Grooves SGLS Naphthenie base oil unextractedAlsoa oi'synthetic fatty acids A? 480 2.56 0.50 4.5 5.2 3.85 4.6 8.17 3.5 4 2,724 0.0040 0.0018 Naphthenic ase oil exi tracted Al soap of synthetic I fatty acids (B) 500 2. 06- 0. 42 0. 4. 0 2. 26 4. 3 2. 67 2.0 2 3, 560 0. 0056 0. 0010 Naphthenic base oil extracted Al soap of synthetic fatty acids free stearic 500 1.35 0.17 0:0 3.1 1.72 4.8 0.92 1.0 2 3.290 0.0040 0.001 acid (0)---. 1,000 2.00 0. 67 0.5 4.5 2. 52 5.0 1.92 0.8 5 3, 580 0.0045 0.0016

' Cleanliness of ring slits, grooves, lands andsides.

Example 2 The same oils were also submitted to arapid test known as the oxidation filter paper test Both of these samples were subjected to the filter paper test described in Example 2 with the following results:

patterned after the test described in the National 8 7 96 Petroleum News vol. 25 No. 37:27 Sept. 13, 1933. h h Tom In this test 300 cc. of the samples are heated at om Ours hours 300 F. in a round bottomed glass cylinder 1%" Sample calcium and aluminum internal diameter and 20" long. A current of s8g1aq:-cl;illeixtmcb% ah .i 2 i s 11 air, 10 liters/hour is bubbled thru the-oil by a p f g fi M11111 1 1 2 4 means of a tube reaching to within V of mp8.

the bottom of the glass cylinder. At intervals of 48, 72 and 96 hours, 10 gr. samples of the oil are withdrawn and filtered thru filter paper and a rating from 1 to 10 is given depending on the discoloration of the paper. Thus a rating of 1 indicates little discoloration while 10 indicates a heavy deposit of sludge.

The results of these tests are summed up below:

The extracted mixture of soaps was an excellent lubricating oil for Diesel engines.

Example 4 H Rating at- 48 72 96 hours hours hours Total .48 -72 96 I Total hours hours hours Unextracted nickel soap 2 5 7 14 I Extracted nickel soap 1 1 2 4 i t" 2 2 2 s 522313011 1 5 50 These data again show the superiority of the It will be observed that these figures, place the oils in the same-relative position as the caterpillar enginetests of Example :1 Example 3 Acids obtained, by oxidation of oil sweated from wax were dissolved in 75% isopropyl alcohol and chlorides in proportion of one mo]. of aluminum to one mol. of calcium. The mixtures were stirred together and a mixture of aluminum and calcium extracted products. Other nickel, chromium, tin and cobalt soaps of various acids such as phenyl stearic, oleic, chlor stearic gave good results and showsimilar improvement on extraction.

which are unsaponified such as esters, lactone lactides, and

tree acids of the-types used in making the heavy metalor polyvalent metal soaps.

'This invention is not to be limited by any specific examples which have been presented herein solely for the purpose of illustration, but only by the following claims, in which it is desired to soap settled out and was filtered off. The filter claim all novelty in so far as prior art permits. cake was washed with alcohol to remove any re- We claim: maining non-saponaceou's materials and the 1. Aprocess for preparing improved lubricants washed'filter cake dissolved in a naphthenic base comprising preparing a soap of a polyvalent oil in order to give an oil containing 0.5% of metal and the acids produced by the'air oxida aluminum soap and 0.5% of calcium soap. This tion of petroleum oils and waxes by reacting an sample is .designated Extracted. Another inorganic salt of the polyvalent metal and an sample wa prepared as in Example 1 ept tha alkali metal derivative of the acids produced by the mixture of calcium and aluminum soapswas the air oxidation of petroleum oils and 1 waxes obtained n aqueous solution and employed in the so as to form a soap of the polyvalent metal and v same proportion as in the previous sample of the said acids, treating said soap with an organic solvent to extract therefrom by solution a substantial portion of the oxy organic impurities of the class consisting of esters, lactones, lactides and free acids of the type used in the preparation of the said soap, dissolving the thus purified soap in a mineral lubricating oil and adding from 0.25% to 1.5% or a tree saturated fatty acid selected from the class of stearic and margaric acids.

2. A process according to claim 1 in which the soap is formed from a polyvalent metal of the second to the eighth group of the periodic table and the acids produced by the air oxidation of the liquid hydrocarbons sweated from crude, solid, waxy hydrocarbons wherein the free saturated fatty acid is stearic acid.

3. An improved lubricant comprising a mineral lubricating oil, a soluble soap of a polyvalent metal of the second to the eighth group of the periodic table and the acids produced by the air oxidation of petroleum oils and waxes, and which is substantially free of oxy organic impurities of the class consisting of esters, lactones, lactides and free acids of the type used in the preparation of the said soap'and 0.25% to 1.5% of a tree saturated fatty acid selected from the class 01' stearic and margaric acids.

4. A lubricant according to claim 3 in which the soap is an aluminum compound in the proportion of from 0.5% to 20%.

5. A lubricant according to claim 3 in which the soap is a nickel compound in the proportion of from 0.5% to 20%.

JOHN G. MCNAB. WALTER T. WATKINS, JR.