Lubricant additive concentrate containing isomerized jojoba oil

Abstract

A crankcase motor oil additive concentrate comprising a detergent-inhibitor package, supplemental antiwear additives, a corrosion inhibitor, and isomerized jojoba oil in a petroleum or synthetic base stock.

Description

BACKGROUND OF THE INVENTION

This invention relates to lubricants used in automobile engines and similar equipment. More particularly, it relates to a novel additive concentrate designed to be added to an ordinary crankcase motor oil to improve its ability to lubricate and protect the engine.

As the internal combustion engines used in automobiles have increased in sophistication and power, the demands made on the crankcase motor oil used in these engines have increased proportionately. Modern gasoline engine oils must meet American Petroleum Institute (API) service rating "SF", a designation which requires the oil to pass a stringent sequence of engine tests to measure its ability to lubricate the engine and reduce corrosion, varnish, and sludge deposits. An "SF" oil will contain a highly refined petroleum or synthetic lubricant base oil which is fortified by antiwear and lubricity additives, detergents and dispersants, rust and corrosion inhibitors antioxidants, antifoam, seal conditioners, pour point depressants and the like. Whereas new oil will contain sufficient additives to meet engine requirements, many of these additives such as the antiwear agents, detergent/dispersants and corrosion inhibitors, are gradually depleted when the oil is in service. The problem is accentuated by the longer oil change inervals that are now common. At one time, motor oils were routinely changed after two or three thousand miles of driving. Today, a drain interval of 7500 miles is a common recommendation of automobile manufacturers, and many drivers tend to put off oil changes even further, with the result that the oil may become seriously depleted of necessary additives, and its ability to protect the engine may be seriously compromised.

A partial solution to this problem is the use of oil additive concentrates, which supplement and enhance the effectiveness of the additive system already present in the used oil. Such oil additive concentrates, added to the crankcase at a treatment level of about 5 to 15% of the regular oil, may replace depleted additives in the original oil and/or introduce new ones. Just as it has been constantly necessary to upgrade crankcase motor oil formulations to satisfy the increasing demands of modern engines, there is a constant need for improved oil additive concentrates to supplement the ability of these oils to protect engines, in view of the rigorous demands made on them by modern motorists. It was an object of my prior invention to provide a novel and improved oil additive concentrate to satisfy this need.

Unexpectedly, I have now discovered that a slight chemical modification (isomerization) of one of the components in the concentrate provides further improved results.

SUMMARY OF THE INVENTION

The oil additive concentrate of my invention comprises the following:

(1) a petroleum base stock of quality and viscosity suitable for the blending of crankcase motor oils;

(2) a detergent-inhibitor package capable of forming a finished crankcase motor oil of API SF quality when added at the appropriate level to a suitable base stock such as (1);

(3) a supplemental antiwear additive selected from the salts of dialkyl dithiophosporic acid, the zinc salt being preferred;

(4) a supplemental antiwear additive selected from the class of sulfurized olefins;

(5) a corrosion-inhibitor selected from the class of overbased sulfonates, the sodium salts being preferred;

(6) and a lubricity additive, comprising jojoba oil which has been subjected to isomerization in order to convert some or all of the naturally occurring CIS isomer into the trans isomer.

The closest prior art of which I am aware is Hollinshead, U.S. Pat. No. 3,849,323, which discloses mixtures of petroleum lubricants, waxes, and polyoxyethlene emulsifiers. Jojoba oil is one of several waxes indicated as useful; however, this reference does not anticipate nor make obvious the compositions of my invention, incorporating isomerized jojoba oil.

DETAILED DESCRIPTION

The following table sets out acceptable and preferred ranges for individual components comprising an additive concentrate:

______________________________________ USEFUL PREFERREDCOMPONENT RANGE(WT. %) RANGE(WT. %)______________________________________(1) Petroleum base stock 25-90 50-75(2) Detergent-inhibitor 7-40 20-30 package(3) Supplemental antiwear 1-10 1-5 additive(4) Supplemental antiwear 1-10 1-5 additive(5) Corrosion inhibitor 0.5-5 1-3(6) Isomerized Jojoba oil 0.1-10 0.2-8______________________________________

The petroleum base stock may be any oil of lubricating viscosity derived from crude oil by the conventional refining processes, as is well known in the art. Such base stocks are usually designated by their viscosity - for example a suitable base stock for my invention is a 450 Neutral oil from Union Oil Corporation, where the number refers to the viscosity in Saybolt seconds and "neutral" indicates refining by distillation. Instead of a petroleum oil, a synthetic base stock such as a hydrogenated polyalphaolefin , dialkylbenzene or a lubricant diester or polyester may be used in the blend, as is well known in the art.

Detergent inhibitor packages are conventionally used in the manufacture of crankcase motor oils and contain the antiwear additives, corrosion inhibitors, detergents and dispersants needed to make a crankcase oil of the desired quality - in this case API Service Rating SF.

Antiwear additives (component 3 above) of the zinc dialkyl dithiophosphate class are used in all modern crankcase motor oils and are familiar to those skilled in the art. Antiwear additives (component 4 above) of the sulfurized olefin class are likewise well known.

Corrosion inhibiting overbased sulfonates are colloidal submicronic dispersions of alkaline and alkaline earth salts, usually carbonates, in an oil solution of an alkaline or alkaline earth alkylbenzene sulfonate salt, derived from an alkylbenzene of natural or synthetic origin having a molecular weight generally in the 250 to 600 range. They are well known in the art.

Jojoba oil is a natural mixture of straight chain unsaturated monocarboxylic acid esters comprising primarily C.sub.18 to C.sub.24 monosaturated alcohols esterified with C.sub.18 to C.sub.24 monounsaturated acids. The double bond is located predominantly in the C.sub.9 position in both the alcohol and acid portions of the esters. As found in nature, jojoba oil molecules have the CIS geometric configuration around the double bonds. Jojoba oil is conventionally cold-pressed from the seed of Simmondsia chenensis, a desert shrub native to California, Arizona, and Mexico.

Isomerized jojoba oil can be prepared by different methods: That described by Brown (U.S. Pat. No. 4,329,298) is a 26% conversion; that prepared by Wisniak (Eng. Chem., Prod. Res. Dev., 14(3): 177 (1975); and Prog. Chem. Fats and Other Lipids, 15:167 (1977)),56% conversion and up. The latter is preferred because of the greater percent Trans Isomer content. These methods convert some or all of the naturally occurring CIS isomer to the trans isomer. It is not necessary to achieve a completed conversion in order to realize the complete benefits of my invention. As little as 20% isomerization is sufficient, although 50% and above is preferred.

The following examples 1, 2 and 3 illustrate blends, blend (1) not containing jojoba oil and blends 2 and 3 containing natural and isomerized jojoba oil, respectively:

______________________________________ Example 1 Example 2 Example 3 (Wt. %) (Wt. %) (Wt. %) Notes______________________________________Petroleum base 67.1 66.1 66.1 (1)stockDetergent-inhi- 25.0 25.0 25.0 (2)bitor packageSupplemental 4.1 4.1 4.1 (3)antiwearadditiveSupplemental 2.5 2.5 2.5 (4)antiwearadditiveCorrosion 1.3 1.3 1.3 (5)inhibitorJojoba oil (natu- None 1.0 Nonerally occurring)Isomerized Jo- None None 1.0joba oil (about50% trans isomer)______________________________________ NOTES: (1) A 450 Neutral oil from Union Oil Corp. (2) An API SF additive package containing 1.3% zinc, 1.2% magnesium, 0.8% nitrogen, 1.2% phosphorus, 8.7% sulfated ash. (3) Zinc dialkyl dithiophosphate containing 8.4% zinc, 7.6% phosphorus, 16% sulfur. (4) Sulfurized olefin containing 43% sulfur. (5) Overbase sodium sulfonate, TBN 440. The composition of Example 1 contains all the components of an additive concentrate disclosed herein with the exception of the jojoba oil, and is therefore considered to be outside the scope of the invention. Example 2, contains the identical components, (1)-(5) plus jojoba oil, the latter not being isomerized. Example 3 contains isomerized jojoba oil, within the present invention.

The compositions of Examples 1, 2 and 3 were compared for their lubricating ability on a friction test machine developed by Wynn Oil Company. In the Wynn friction tester, a steel race consisting of a Timken test cup rotates at 760 rpm against a tapered Timken steel roller bearing held in a container of the lubricant to be evaluated. Approximately 20 mls of lubricant are used. The bearing holder is connected to a lever arm arrangement culminating at a pan to which weights can be added to increase the contact force between the bearing and the race. A thermocouple is used to measure the increase in temperature in the lubricant as the test proceeds. The Wynn friction tester is conventionally run in two different ways. In the first, a constant weight is applied for an extended period, usually an hour and the temperature increase and the size of the wear scar on the bearing are determined. A smaller wear scar and a lower lubricant temperature at the conclusion of the test indicate a higher level of lubricant protection and reduced friction between moving parts. In the second test procedure, the load on the bearing and race is increased at a regulated rate by the addition of weights to the pan. Failure occurs when the rotation of the race is halted by welding between the bearing and race.

The compositions of Examples 1, 2 and 3 were dissolved at a 10% level in a 150 Neutral petroleum base stock from the Union Oil Corporation. The solutions were then run for one hour on the Wynn friction tester. A load of two one-pound weights was applied to the pan, and oil temperatures and the wear scars on the bearings were measured. The following results were obtained:

______________________________________ Example 1, 10% Example 2, 10% in 150 Neutral in 150 Neutral______________________________________Temp. .degree. F.Initial 75 7523 min. 182 17930 min. 185 18145 min. 190 18860 min. 191 190Wear Scar Area 0.0728 0.0657(Square inches)______________________________________ Note that the oil blend containing 10% of Example 2 which included the jojoba oil, ran consistently cooler and left a significantly small wear scar on the bearing than the 10% solution of Example 1, which contained no jojoba oil and is outside the scope of my invention. This is especially remarkable in light of the fact that the additive concentrate of Example 2 contains only 1.0% jojoba oil and that the 10% solution actually tested contained only 0.1% jojoba oil. The significant improvement in lubrication achieved by the inclusion of such a minor amount of jojoba oil would certainly not have been obvious to an ordinary skilled worker. The blend may preferably consist essentially of between 5 and 15 weight percent additive concentrate as defined above blended with between 95 and 85 weight percent new fully formulated motor oils; or may consist essentially of between 5 and 15 weight percent additive concentrate as defined above blended with between 95 and 85 weight percent used crankcase motor oil.

The following tests were carried out to establish the usefulness of the additive concentrates of the invention in improving the lubricating properties of used crankcase motor oil. A sample of a used API SF quality crankcase oil (viscosity grade SAE-10W/400) was evaluated on the Wynn's friction test machine and compared to a sample of the same used oil, to which had been added 10% of the composition of Example 2. In these runs, the number of weights on the pan was incresed until welding occurred. Four trials were made on the used oil, and on the used oil containing the compositions of Example 2, and the number of weights that each lubricant would support before failure (welding) was calculated. In addition the average lengths of the scars were determined. The results were as follows:

______________________________________ Used Oil Plus 10% Used Oil by weight of composition Alone of Example 2______________________________________No. of weights carried 5 9Scar length (in.) 0.189 0.162______________________________________ The addition of the additive concentrate of my invention to the used oil increased the number of weights it was capable of carrying from 5 to 9, indicating a dramatic increase in lubricant protection. Moreover, the addition of Example 2 composition resulted in reduced wear on the bearing, as evidenced by the shorter wear scar. This test illustrates the ability of the additive concentrate of my invention to substantially or significantly enhance the lubricant protection of a conventional used crankcase oil.

The composition of Example 3 was also compared for lubricity ability on the Wynn Oil Company friction test machine, in the same manner as Examples 1 and 2 were compared, and the following results were obtained: the performance of the Example 3 blend was for the intermediate temperatures approximately 12.5% better in weight carrying ability than the Example 2 blend using non isomerized wax esters. Under high temperature conditions the isomerized wax carried approximately 25% more weight than did the non isomerized wax.

The Example 3 blend also ran consistently cooler than Example 2, and left a significantly smaller wear scar area on the bearing than the 10% solution of both Examples 1 and 2.

This example of an oil additive is suitable for addition to fully formulated engine oils. This type additive enhances the performance of the active ingredients or, in the case of stressed oils (those which have been in use), replaces ingredients which have been depleted. In addition to the above, the isomerized jojoba wax esters present in the additive are effective in modifying the frictional characteristics of the fluid.

A further example of a motor oil additive comprises the following ingredients:

______________________________________ Wt. %______________________________________(a) Detergent inhibitor 7.0-40%(b) Oxidation inhibitor 1.0-10% and antiwear agent(c) High Sulfur extreme 1.0-15% pressure agent(d) Corrosion inhibitor 0.5-1.5%(e) Isomerized jojoba wax 0.5-20% esters(f) a synthetic lubricant balance base stock______________________________________

Advantages of trans-isomerized Jojoba wax esters over normal Jojoba wax esters are:

1. As determined by the Shell 4 Ball Wear Tester under conditions of high speed and moderate load (1800 RPM-20KG), the isomer wax containing product had smaller scars developed than did the non isomerized product.

2. Utilizing the Wynn Oil Company developed friction demonstrator machine (Lab modification) which is a highly modified Timken wear tester, the performance of the isomerized wax ester was, for the intermediate temperatures, approximately 12.5% better in weight carrying ability than the same product using non isomerized wax esters. Under high temperature conditions the isomerized wax carried approximately 25% more weight than did the non isomerized wax.

The contents of Ser. No. 671,116, filed Nov. 13, 1984, are incorpoated herein, by reference.

Claims

1. A crankcase motor oil additive concentrate intended to be added to a conventional crankcase motor oil to improve its ability to lubricate and protect the engine, said additive concentrate comprising the following components:

(a) a petroleum base stock of lubricating quality and viscosity said base stock comprising from about 13.5 to 90 weight percent of the additive concentrate;

(b) a detergent-inhibitor package, said package being present at from about 7 to about 40 weight percent of the concentrate;

(c) a supplemental antiwear additive selected from the salts of dialkyl dithiophosporic acids, said additive being present at a level of from about 1 to about 10 weight percent of the concentrate;

(d) a supplemental antiwear additive selected from the class of sulfurized olefins, said additive being present at a level of from about 1 to about 10 weight percent of the concentrate;

(e) a corrosion inhibitor selected from the class of overbased sulfonates, sadi inhibitor being present at about 1 to about 1.5 weight percent of the concentrate; and

(f) isomerized jojoba oil present in an amount of from about 0.5 to about 20 weight percent of the concentrate.

2. The motor oil additive concentrate of claim 1 wherein the component (b) detergent-inhibitor package is present at a level of 20 to 30 weight percent of the concentrate.

3. The concentrate of claim 2 wherein component (c) consists of zinc salts of dialkyl dithiophosphoric acid which are present at a level of 1 to 5 weight percent of the concentrate.

4. The concentrate of claim 3 wherein component (d) sulfurized olefin is present at a level of 1 to 5 weight percent of the concentrate.

5. The concentrate of claim 4 wherein the component (e) overbased sulfonate is present in the form of a sodium salt and at a level of 1 to 3 weight percent of the concentrate.

6. The concentrate of claim 5 wherein the component (f) isomerized jojoba oil is present at a level of 0.5 to 8 weight percent.

7. An oil blend consisting essentially of between 5 and 15 weight percent additive concentrate as defined in claim 1 blended with between 95 and 85 weight percent used or newly formed, or formulated crankcase motor oil.

8. A method of improving the ability of a conventional crankcase motor oil to lubricate and protect the engine which includes the step of adding to said motor oil from about 5 to about 15% by weight of the additive concentrate of claim 1.

9. A motor oil additive comprising the admixed ingredients:

(a) between 7 and 40 weight percent detergent inhibitor package.

(b) between 0.5 to 20.0 weight percent isomerized jojoba wax esters, and

(c) diluent motor oil.

10. A motor oil additive comprising the following admixed ingredients:

______________________________________ Wt. %______________________________________(a) Detergent [Detergent] 7.0-40% inhibitor package(b) Oxidation inhibitor 1.0-10% and antiwear agent(c) High Sulfur extreme 1.0-15% pressure agent(d) Corrosion inhibitor 0.5-1.5%(e) Isomerized jojoba 0.5-20% wax [was] esters(f) a synthetic lubricant balance base stock______________________________________

11. The additive concentrate of claim 1 wherein the isomerized jojoba oil is a mixture of CIS and trans isomer.

12. The additive concentrate of claim 11 wherein the isomerized jojoba oil contains in excess of 20% by weight trans isomer.

13. The additive concentrate of claim 11 wherein the isomerized jojoba oil contains above 50% by weight trans isomer.