US3250709A - Mixed salt lubricants containing asphalt to eliminate haze - Google Patents

Description

haze.

3 250 709 MIXED SALT LUBRICANTS CONTAINING ASPHALT T ELIMINATE HAZE Arnold J. Morway, Clark, N.J., and Ralph E. Darley,

Glen Buruie, Md., assiguors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Aug. 31, 1964, Ser. No. 393,347

5 Claims. (Cl. 25232.7)

weight fatty acids and containing a small amount of asphalt to prevent haze.

Fluid lubricants containing alkaline earth metal mixed salts have come into use for marine diesel cylinder lubrication because these mixed salts have good anti-wear and load-carrying abilities, in addition to their ability to neutralize-free acid. For example, a fluid lubricant containing calcium mixed salts of acetic acid and C to C fatty acid made by coneutralizing the acids with lime, was very successful commercially as a marine diesel lubricant. Haze was not a problem with this particular lubricant since the lubricant was opaque and any haze could not be seen. In this prior lubricant, the calcium acetate salt primarily provided the anti-wear and loadcarrying properties, while the intermediate molecular weight, i.e. C to C fatty acid salt served primarily as a stabilizing and suspending agent for maintaining the calcium acetate suitably dispersed in the oil. However, due to the short chain length of the intermediate fatty acid salts, their suspending power for the calcium acetate was not as great as desired, with the occasional result that some separation of oil and salt occurred in storage and in use, leading to plugged lines and valves. It was then found that these marine diesel lubricants could be further improved in their stability by using certain additives known as sludge dispersants for crankcase lubricating oils, particularly when using a highmolecular weight fatty acid in place of part or all of the intermediate molecular weight fatty acid. This use of high molecular weight fatty acid, in combination with the surfactant effect of the sludge dispersant, can result in liquid lubricants of exceptional stability against sedimentation and separation, and which are transparent since the particle size of the. calcium acetate component is colloidal when made in the presence of the aforesaid sludge dispersant. However, these transparent lubricants are frequently hazy.- It is not known with certainty what causes the haze, although it is believed caused by water from the salt formation which is not removed by the normal dehydration of the lubricant, and which for some reason will not separate from the lubricant. This haze is objection-able since it frequently leads the consumer to mistakenly believe the product is inferior and thus presents a serious marketing handicap.

The present invention is based upon the discovery that the addition of asphalt to the aforesaid lubricant, and similar mixed salt lubricants, will eliminate the haze to thereby obtain a clear, bright product. It is not known why the asphalt is effective in removing and preventing haze. One possibility is that the high molecular weight asphalt components react chemically or physically with the colloidally suspended haze, and since the asphalt is United States Patent 0 "ice oil soluble, that it somehow carries the haze into solution, thereby giving a clear product.

Usually about .001 to 0.2 wt. percent, preferably .002 to .020 wt. percent, of asphalt will be added to the mixed salt lubricant to eliminate haze.

The asphalt, for convenience in dissolving in the lubricant, is preferably used in the form of an asphaltic oil such as a residuum oil. These asphaltic residuum oils generally have a viscosity of 210 F. of about 200 to 1350 SUS, and contain about 2 to 20 wt. percent of asphalt measured as Holde hard asphalt. Preferred residuum oils will have a viscosity of 210 F. of 250 to 1,000 SUS and contain 3 to 12 wt. percent of asphalt measured as Holde hard asphalt. Holde hard asphalt is that asphalt insoluble in 86 degree (API) naphtha.

The asphaltic residuum oils can be obtained as residues -by distillation of asphaltic petroleum crude oils such as those of South America, e.g. Lagunillas; California, e.g. San Joaquin; or Mid-Continent crudes; etc. The asphaltic oil of the invention can also be prepared by cutting back asphalt with mineral oil. Natural asphalts, such as Trinidad, Bermudez, gilsonite, g-rahamite, and Cuban asphalt 'can also be used.

The mixed salt lubricants of the invention will generally comprise a major amount of mineral lubricating oil and about 2.0 to 20.0 Wt. percent of alkaline earth metal mixed salts of low and higher molecularweight fatty acids, and about 0.1 to 7.0 wt. percent of a dispersant. The dispersant is for colloidally dispersing the insoluble low molecular Weight fatty acid salt so as to make a transparent lubricant. Preferably, the lubricant will contain 4.0 to 12.0 wt. percent of the fatty acid salts and 0.3 to 2.0 wt. percent dispersant.

The alkaline earth metal mixed salts will generally be a mixture of salts of about 2.0 to 8.0 molar proportion of low molecular weight acid per molar proportion of high molecular weight fatty acid. There may also be present salt of up to 5 molar proportions of intermediate molecular weight, e.g. C to- C fatty acid per molar proportion of said high molecular weight acid.

The alkaline earth metal component of the mixed salts include calcium, barium, strontium and'magnesium, al-' though calcium is preferred. Usually, the fatty acids are coneutralized with alkaline earth metal base, e.g. a hydroxide, oxide or carbonate. Lime (calcium hydroxide) is preferred.

The low molecular Weight fatty acid component of the mixed salt will include those of 2 to 4 carbon atoms such as acetic, propionic, etc. Acetic acid or its anhydride is preferred.

Operable C to C fatty acids are capric, caproic, lauric, etc. These acids are usually commercially available as mixtures, e.g. coconut oil acid.

Examples of the high molecular weight fatty acids are the C to C fatty .acids including tallow fatty acids, oleic, palmitoleic, gadoleic, erucic, arachidonic, myristoleic acid, etc. Thes fatty acids are usually derived from either animal or vegetable sources. In some cases, commercial fatty acid derived from naturally occurring materials will contain both saturated and unsaturated acid. For example, some commercial fatty acids will contain about 40 or even 60 wt. percent of saturated fatty acids,

with the remainder being principally mono-unsaturated fatty acid along with minor amounts of polyunsaturated Wijs iodine numbers of about 35 to 110, preferably 40 to 80, and saponi-fication numbers of 250 to 150, preferably 225 to 175 mg. KOH/ gm.

The dispersant is one of a class of materials used in lubricating oils, such as crankcase motor oils, to disperse sludge. One preferred type of these materials are the phosphos-ulfurized olefins, which are well known and are prepared by reacting an olefin or an olefin polymer with P S to form a material believed to be a dithiophos-phoric acid. More specifically, the phosphosul-furized olefins are generally prepared by reacting phosphorus pentasulfide with a polymer of a monoolefin, e.g. an alpha olefin, having 2 to 6 carbon atoms, said polymer having a molecular weight in the range of 600 to 4,000 Staudinger, preferably 700 to 1400 Staudinger, for about 0.5 to hours at 150 to 600 F. P 8 treated polyisobutylene is particularly preferred. Preparation of these phosphosulfurized polyolefin-s is more fully described in US. Patent 2,875,188. The phosphosulfurized polyolefin can be used per se, or it can be first hydrolyzed, or it can be used in the form of its metal salt. Hydrolyzation is readily carried out by treating the phosphosulfurized polyolefin with steam to thereby increase the acidity o fthe phosphosulfurizcd polyolefin. This hydrolyzation technique and product is also well known in the art.

Other useful sludge dispersants are amino alkyl phenols and their salts, such as those described in US. Patents 2,353,491; 2,459,112 and 3,036,003. A particularly preferred material of this type is prepared by reacting two moles of nonyl phenol with one mole of ethylene diamine and two moles of formaldehyde. Another recently developed sludge dispersant is polyisobutylene succinic anhydride wherein the isobutylene group has a molecular weight of about 700 to 1200, as well as polya-mine derivatives thereof, namely amic acids and imides obtained by reacting polyamines, for example tetraethylene pentamine, wit-h said aforesaid polyisobutylene succinic anhydride. An example of materials of this type is described in English Patent No. 922,831. Another dispersant is alkaline earth metal petroleum, or synthetic, alkyl aryl sulfonates of about 300 to 700 molecular weight.

While the preceding dispersants differ considerably from each other in their chemical composition, they are all characterized by their oil-solubility and their common physical ability to maintain small particles stably dispersed in oil. And for the purpose of this invention, the chemical nature of the dispersant does not appear important, rather it appears to be the physical ability of the dispersant to disperse the otherwise substantially oil-insoluble salt of the low molecular weight fatty acid in very fine or colloidal size particles, so as to make a transparent lubricant. These dispersants are preferably present as the low molecular weight fatty acid salt is formed in situ in the lubricating oil, and if the dispersant is an acid, it can be simultaneously neutralized to metal salt along with the fatty acid, since the salt forms of the above-noted sludge dispersants are also effective as dispersants.

The mixed salt lubricants will usually be prepared by coneutralizing the fatty acids in the presence of oil and dispersant, with the alkaline earth metal base, followed by dehydration at a temperature of about 250 to 350" F. If the dispersant is an acid, it will be converted into its salt form. For purposes of economy, concentrates containing salt of 10 to 40 wt. percent, usually to wt. percent, of the fatty acid mixture, will be first prepared and then later diluted with additional oil to form the final lubricant of the invention.

The mixed salt lubricants frequently contain various other additives in amounts of 0.1 to 10.0 wt. percent, based on the weight of the finished lubricant. Among additives that can be used are corrosion inhibitors such as sodium nitrite, lanolin, wool grease stearine; antioxidants such as phenyl m-napthylamine; auxiliary extreme pressure agents; auxiliary antiwear agents; dyes; etc.

The invention will be further understood by reference Glacial Acetic Acid;

to the following example which includes a preferred embodiment of the invention.

EXAMPLE I.PREPARATION OF CONCENTRATE A mixed salt concentrate was prepared having the following formulatino, wherein all percents are weight percents:

Percent Glacial acetic acid 22.35 Tallow fatty acid (beef tallow), sap. No. 195, Wijs iodine No. 55, ave. C chain 3.51 Phosphosulfurized polyisobutylene 3.40 Hydrated lime 14.63 Phenyla-naphthylamine 0.27 Mineral lubricating oil of SUS vicosity at The oil, tallow fatty acid, phosphosulfurized polyisobutylene, and hydrated lime were mixed together in a steam jacketed grease kettle. Then, acetic acid was slowly added over about a six hour period, while mixing and while keeping the temperature of the kettle contents below F. The resulting grease mixture was then heated to 300 F. in order to dehydrate said mixture. The product was then cooled to 250 F., where phenyla-naphthylamine was added, and was then further cooled to room temperature. Mixing was carried out during the entire process described above by cycling the kettle contents through 3 Charlotte colloidal mill and then back to the kettle.

The phosphosulfurized polyisobutylene was prepared by reacting polyisobutylene of about I 800 molecular weight (Staudinger) with 15 wt. percent P 8 based on the weight of polyisobutylene, at about 425 F. for about 8 hours under a nitrogen atmosphere.

18.525 parts of the concentrate were mixed with 81.456 parts of additional mineral lubricating oil of 78 SUS viscosity at 210 F. to thereby form a finished diesel engine cylinder lubricant containing no asphalt. The mixture was hazy. Then 0.10 part of a residuum oil which contained asphalt, was mixed into the lubricant, whereupon said lubricant became clear and free of haze. This residuum oil was obtained by distillation of Lagunillas asphaltic crude oil and had a viscosity of about 800 SUS at 210 F. and contained about 5 wt. percent of Holde hard asphalt.

The lubricant, with and without the asphalt-containing residiuum oil, and its properties are summarized in Table I which follows:

Table I Tallow Fatty Acids Phosphosulfurized Polyiso- 4 butylene. Hydrated Lime Phenyl-u naphthyla-mine Mineral lubricating oil of 60 SUS viscosity at 210 F. Mineral lubricating oil of 78 SUS v'scosity at 210 F aesiduum on 5% asphalt) 0.00 0.10.

roperties:

A earance Light Yellowish- Dark Brown pp Green, Hazy. Clear. SSUVisJlOO" F 1.3M

SSU Via/210 F Engler Vis. 50 C 18 Ash percent as CaSO4 Total Base No Centrifuge, percent Sediment As seen by the preceding table, the addition of 0.1% of residuum oil so as to incorporate 0.005% asphalt in the lubricant removed the haze and gave a clear product and also reduced the amount of sediment that separated when the lubricant was centrifuged. At the same time, there was substantially no other change in the lubricants properties except a darkening of color, which is not objectionable as long as a clear product is obtained.

In the preceding example the amounts of hydrated lime are such as to neutralize the acetic and tallow acid as well as the phosphosulfurized polyisobutylene which is converted to metal salt. polyisobutylene can be used in its non-salt form. To illustrate, Example I can be repeated by decreasing the amount of lime so it is just sufiicient to neutralize the acetic and tallow acids, correspondingly increasing the amount of oil and adding the phosphosulfurized polybutylene after the neutralization, or after dehydration and cooling of the lubricant.

As a further illustration of the invention, Example I can be repeated but replacing the phosphosulfurized polyisobutylene with an equal molar equivalent amount of polyisobutylene succinic anhydride wherein the polyisobutylene group has a molecular weight of 1100 and correspondingly adjusting the amount of lime and mineral oil so as to obtain a neutral product. Or Example I can be repeated but using in place the phosphosulfurized polyisobutylene, a mole equivalent amount of the reaction product of 2 moles of nonyl phenol with 1 mole of ethylene diamine and 2 moles of formaldehyde. As in the case of the phosphosulfurized polyisobutylene, the foregoing dispersants can be present either during the neutralization of the fatty acids which is the preferred method and wherein the dispersant is converted into the corresponding alkaline earth metal salt or the dispersant can be added after this neutralization. The purpose of the dispersant is to aid in dispersing the mixed salt so finely that the lubricant is transparent and, as long as this is achieved, the exact dispersant used or how it is used is not critical.

In summary, the present invention resides in the discovery that small amounts of asphalt can be used to convert a hazy, transparent, fluid, mixed salt lubricant into a haze-free clear product.

What is claimed is:

1. A haze-free transparent fluid lubricating composition comprising a major amount of mineral lubricating oil containing about 2 to 20 wt. percent of alkaline earth metal mixed salt of C to C fatty acid and C to C fatty acid in a relative molar ratio of about 2 to 8 molar equivalent proportions of said C to C fatty acid per mole equivalent of said C to C fatty acid, about 0.1 to 7.0 wt. percent of a lubricating oil sludge dispersant, and about .001 to 0.2 wt. percent of asphalt.

2. A lubricant according to claim 1, wherein said dis-' persant is selected from the group consisting of phosphosulfurized polymers of C to C monoolefins having a molecular weight of about 600 to 4,000 Staudinger, alkaline earth metal salts of said polymers, amino alkyl However, the phosphosulfurized phenols, alkaline earth metal salts of said amino alkyl phenols, polyisobutylene succinic acid having a polyisobutylene group of about 700 to 1200 molecular weight,-

alkaline earth metal salts of said acid, condensation products of said acid and polyamine, and alkaline earth metal alkyl aryl sulfonates of about 300 to 700 molecular weight.

3. A haze-free substantially transparent, lubricating composition comprising a major amount of mineral lubricating oil and within the range of about 2 to 20 wt. percent of alkaline earth metal mixed salt of C to C fatty acid and C to C fatty acid having a Wijs iodine number of about 35 to 110, in a relative mole ratio of about 2 to 8 molar equivalent proportion of said C to C fatty acid per mole equivalent of said C to C fatty acid and alkaline earth metal salt of about 0.1 to 7.0 wt. percent of alkaline earth salt of phosphosulfurized polymer of a C to C monoolefin as a dispersant, said polymer having a molecular weight of about 600 to 4,000 Staudinger, and about .001 to 0.2 wt. percent of asphalt.

4; A lubricating composition according to claim 3, wherein said alkaline earth metal is calcium, said C to C fatty acid is acetic acid, said G to C fatty acid is beef tallow acid, and said monoolefin is isobutylene.

5. A haze-free substantially transparent fluid lubricating oil composition suitable for marine diesel cylinder lubrication comprising a major amount of mineral lubricating oil, about 4 to 12 wt. percent of calcium mixed salt of acetic acid and C to C fatty acid in a molar ratio of about 2 to 8 mole equivalent of acetic acid per mole equivalent of C to C fatty acid, and about 0.3 to 2.0 wt. percent of calcium salt of P treated polyisobutylene having a molecular weight of about 700 to 1400 Staudinger, and about .002 to .020 asphalt.

References Cited by the Examiner UNITED STATES PATENTS 1,708,563 4/1929 Black et al 25259 X 2,104,097 1/1938 Pier et al 25259 X 2,353,491 7/ 1944 Oberright 25242.7 X 2,976,242 3/1961 Morway 25239 XR 3,125,521 3/1964 Detweiler et al. 25240.7 X

FOREIGN PATENTS 922,831 4/ 1963 Great Britain.

OTHER REFERENCES Cross: The Handbook of Petroleum, Asphalt and Natural Gas (1931), p. 524.

DANIEL E. WYMAN, Primary Examiner.

C. F. DEES, Assistant Examiner.

Claims (2)

1. A HAZE-FREE TRANSPARENT FLUID LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL CONTAINING ABOUT 2 TO 20 WT. PERCENT OF ALKALINE EARTH METAL MIXED SALT OF C2 TO C4 FATTY ACID AND C14 TO C30 FATTY ACID IN A RELATIVE MOLAR RATIO OF ABOUT 2 TO 8 MOLAR EQUIVALENT PROPORTIONS OF SAID C2 TO C4 FATTY ACID PER MOLE EQUIVALENT OF SAID C14 TO C30 FATTY ACID, ABOUT 0.1 TO 7.0 WT. PERCENT OF A LUBRICATING OIL SLUDGE DISPERSANT, AND ABOUT .001 TO 0.2 WT. PERCENT OF ASPHALT.

2. A LUBRICANT ACCORDING TO CLAIM 1, WHEREIN SAID DISPERSANT IS SELECTED FROM THE GROUP CONSISTING OF PHOSPHOSULFURIZED POLYMERS OF C2 TO C6 MONOOLEFINS HAVING A MOLECULAR WEIGHT OF ABOUT 600 TO 4,000 STAUDINGER, ALKALINE EARTH METAL SALTS OF SAID POLYMERS, AMINO ALKAYL PHENOLS, ALKALINE EARTH METAL SALTS OF SAID AMINO ALKYL PHENOLS, POLYISOBUTYLENE SUCCINIC ACID HAVING A POLYISOBUTYLENE GROUP OF ABOUT 700 TO 1200 MOLECULAR WEIGHT, ALKALINE EARTH METAL SALTS OF SAID ACID, CONDENSATION PRODUCTS OF SAID ACID AND POLYAMINE, AND ALKALINE EARTH METAL ALKYL ARYL SULFONATES OF ABOUT 300 TO 700 MOLECULAR WEIGHT.