US2201767A - Lubricating oil - Google Patents

Description

Patented May 21, 1940 UNITED STATES" PATENT OFFICE sonville, Ky., by James A. administrator, Madisonville, Ky.,

Franceway, Sr., and Garland H. B. Davis, Elizabeth, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application July 2, 1936, Serial No. 88,612

26 Claims.

Lubricating oils obtained from petroleum and especially the higher grade lubricating oils contain waxy constituents and in consequence thereof are characterized by high pour points, that is to say, they become solid at relatively elevated temperatures, for example 30 or 40 F.

or even 50 or F., depending on the amount of wax present. It is the practice of refiners to remove a part or the whole of the wax so as to cause the oil to remain liquid to considerably lower temperatures, for example to 10 F. or even to 0 F. or lower, but this is an expensive operation and besides the wax is a desirable addition agent to the oil so that it is preferred not to remove it.

We have discovered a class of substances which when added to hydrocarbon. oils improve their properties and when added to Wax-containing oils even in small amounts cause the wax to crytallize in such a manner that the oil will remain fluid, and will pour at tem eratures considerably below the normal pour points. These materials are also effective in decreasing the sludging tendencies of petroleum lubricating oils and in rendering such oils resistant to oxidation.

The substances which we have prepared are polymers of high molecular weight, soluble in oil and which do not undesirably afiect the other properties of the oil. The polymers ofa particular type produced in' a special manner from certain raw materials form the basis of the present invention.

The raw materials are contained in the general class of oxygenated organic materials which have relatively long straight .hydrocarbon chains of, for example, 10 or 12 carbon atoms or more. They are preferably saturated. oxygenated derivatives of the hydrocarbons contained in parafiin wax are desirable since they are characterized by substantially straight chains. The normally liquid oils containing more than 10 or 12 carbon atoms per molecule are sometimes characterized by a marked branchy and/or cyclic structure and if so are undesirable for the present purposes.

It is not, however, necessary that the chains of the oxygen-containing compounds be fully saturated. Olefins of more than 10 carbonatoms arranged in a relatively long straight chain are equally desirable.

These desirable polymers may be produced from any compounds selected from the class of the alcohols, esters, ethers, acids, ketones and the like which contain hydrocarbon groups of at least 10 carbon atoms in substantially straight chains, and which contain, it any, preferably not more than one carboxylic group. For example, stearic acid or its esters such as the methyl. ethyl 01' propyl stearates or oleic acid and its esters may be used; the alcohols above decyl, the corresponding aldehydes and ethers of such alcohols and related substances such as the ketonesare also available. While we prefer the naturally occurring acids or esters because of their cheapness, materials produced synthetically which may be mixtures of many different compounds,

or of compounds of the same type but .of different number of carbon atoms, may be used with good results.

The method by which the above enumerated substances are treated to produce suitable polymers consists in the application thereto of high tension electric discharges. The process is carried out in the known manner under reduced pressure preferably below about mm. absolute pressure but more elevated pressures about to atmospheric, say 650 mm.'may be used, and provision is made for continuously maintaining this reduced pressure. An alternating current of 60 cycles per second, for example, may be used but it is far more desirable to have greater frequencies, say 10,000, 15,000 or even much higher. High voltages are also necessary, say 10,000 to 15,000 orhigher, depending on the film of oil through which the current is to pass.

Any suitable apparatus as indicated above can be used for our purpose, and many types are well known. The temperature of the material should be sufficient to keep it in a fluid state and it may be caused to flow in a thin film over the electrodes or, to splash, foam or squirt over them in such a way as to subject the oil in thin films to the action of the high tension discharge.

The electrodes may beplaced in parallel, or in the form of plates which may be alternately dipped into and withdrawn froma bath ofthe material or, they may be in the form of concentrically placed tubes or drums arranged. in a horizontal direction and rocked about the horizontal axis through say 100 to degrees or slowly rotated, and in this way the oily material which may occupy something less than one-half of the annular space between the electrodes is washed up over the inner and the outer tube in such a way as to leave a film exposed to the current. If desired, a small amount of gas, for instance nitrogen orhydrogen may be bubbled through the material undergoing treatment causing it to splash or foain. If desired, concentric'electrodes may be used and rapidly rotated so as to cause the'film of oil to form on the outer electrode where it is thrown by centrifugal force.

In small scale equipment it has been found desirable to continuously add heat to the material either by jacketing the vessel or by withdrawing a portion of the material, heating it, and returning it to the vessel so as to maintain the wax or other solid material in a freely flowing liquid state. If the oil is naturally liquid ordinary temperatures are permissible, but even in that case slightly. elevated temperatures from, say 100 to 500 F. or more, are desirable to keep the polymer in a state of reduced viscosity. In larger scale equipment where radiation losses are necessarily lower, less heat is required but it is ordinarily desirable in any case to provide thermostatic jackets so as to keep the conditions substantially the same during the treatment.

The polymers which we desire to form have molecular weights well in excess of 600 and substances as high as 1000 to 2000 and perhaps higher have been found in the product. The lower polymers apparently do not possess the desired pour depressing properties but it is extremely difficult to separate fractions closely and to state to a substance of a cyclic structure such as benzol' with exactitude at just what point this action begins. It may be stated, however, that unpolymerized fractions of the original material, for example alcohol may be removed from the heavier polymers by distillation and that the vaporized material generally possesses no pour inhibiting properties ,or, in any case. it is very weak and that the bottoms or residue concentrates the valuable or active material. The lighter fractions may be returned for retreatment in the same or in a successive treatment. The distillation should be conducted with fire and steam or with vacuum. and care should be taken to remove the lighter fractions without any substantial cracking of the residue.

While the oxygen-containing paraffinic material, by which we mean material containing relatively long hydrocarbon chains and oxygen, may be used along, it is permissible to add thereor naphthalene, their hydrogenated or alkylated derivatives such as toluol, xylol and ethyl naphthalene. Hydroxylated aromatics, such as the phenols and naphthols, may be used for this purpose, as well as the nitrated aromatics or the amino derivatives of the type of aniline, naphthylamine and the like. Even' cyclic terpenes may be used. These materials are added in proportion of, say 10 to 14 or of the paraflinic material and the condensation takes place in substantially the same manner as indicated above, but it is clear that the aromatic or cyclic material actually takes part in the combination.

The time of treatment varies according to the power input and consequently if that is low a time 'of say 100 or 150 hours may be required,

whereas if it is higher the work may be accomplished in 50 or hours or even in less time. The amount of material to be used for our purposes may be generally described as in pour inhibiting proportions. If too much of the material is used the pour inhibiting effect tends to diminish so that there is a decided optimum for pour depressing. The actual amount to ,be used, of course, also depends on the concentration of the active substance in the oily polymers. Ordinarily, if a good grade of polymer is produced 1 is suiilcient, but in some instances as little as..1 to .5% may be sufiicient, and in other cases 2 to 5% may be required. It is desirable, as indicated above, to concentrate the inhibitor to some extent and this is preferably done by distilling oil? the lower readily distillable fractions, for example, by vacuum distillation or by other suitable means. Where the agent is well concentrated the pour inhibiting eifect may be obtained without substantial increase in viscosity.

The polymers also serve to stabilize lubricating oils against oxidation and development of sludge. They are effective as oxidation inhibitors and sludge preventers in oils which contain little or no wax, as well as in waxy oils. They are effective for these purposes in concentrations of about 0.1% to 5 or 10% and may be usedin even larger amounts, ordinarily lor 2% will be found satisfactory.

The following examples are presented to illustrate suitable methods for the preparation of the herein described products, and their use in lubricating oil blends.

.Errample 1.-An alcohol fraction was prepared by oxidizing at a low temperature a paraffin wax derived from petroleum. Non-acidic oxygen containing components were separated from the saponified oxidation product and from themoxidizedhydrocarbons by extraction first with naphtha and then with aqueous methanol. The alcohol extract was distilled under vacuum at an absolute pressure of 20 mm. of mercury, the 0-56% out being recovered as distillate. This distillate of crude alcohols was hydrogenated to convert the ketones therein to alcohols. The hydrogenated alcohol fraction was then subjected to silent electric discharge of an alternating current of 1200 cycles at 7000 volts at a pressure of about 4 cm. of mercury. Hydrogen was passed through the oil throughout the test to promote foaming. By this means the alcohol fraction are presented in the following table:

Oxidation rate Lubricating oil g g cc. 01/125151. Oil/i6 A, (65 vis/2l0F.) l 1.3 103, 108, 67, 59 A. +2% Voltolized alcohols. 0.5 55, 72, 53, 42 B. (46 vis/Zl0 F.) 13. 4 82, 92, 7], 51 B. +2% unvoltolized alcohol 11. l 0, 105, 72, 61 B. +2% Voltolized alcohol 1.1 50, 44, 4D, 51

Example 2.Cetyl alcohol was thickened by subjection to silent electric discharge until a Voltolized product having a viscosity of 600 seconds Saybolt at 210 F. was obtained. 2% of this voltolized cetyl alcohol was added to a petroleum lubricating oil having a Sligh number of 12. The Sligh number of the resulting blend was 0.8, thereby indicating a very substantial reduction in the sludging tendency of the oil. Voltolized stearyl alcohol and Voltolized lauryl alcohol gave comparable reductions in the Sligh number of the lubricating oil.

The tendency of a lubricating oil to form separable sludge is determined by the Sligh test which involves exposing a sample of the oil to the action of oxygen at 392 F. The Sligh test is described in Proc. A. S. T. M., vol. 24, 964 II (1924). The Sligh number of an oil is the number of milligrams of sludge deposited by 10 cc. of the oil when treated at the temperature specified for a given time with a given quantity of oxygen.

The susceptibility of a lubricating oil to oxidation at motor operating temperatures is determined by measuring the amount of oxygen that a given sample of the oil will absorb in a given time at a given temperature when blown with oxygen at a given rate. This test asconducted in the above examples is a determination of the number of cc.'s of oxygen absorbed by 10 gm. of the oil per minute interval of exposure at 392 F. i

While it is preferred to electricallytreat the raw material in a substantially concentrated state, it can be polymerized while dissolved in "a suitable oil stock such as a lubricating oil or a hydrogenated lubricating oil. The oil may also contain substantial amounts of wax. The oil in such case is polymerized to some extent as will be appreciated, and even though the product may be rich in wax, it still has a low pour point due to the presence of the inhibitor produced in situ. This product can be used as an inhibitor and added to other oils such as natural waxy oils or to hydrogenated or synthetic oils, or may be used as a lubricant as such.

Our invention is not to be limited by any theory of the mechanism of electrical condensation, nor of pour reduction, but only to the following claims in which we wish to claim all novelty inherent in the invention.

We claim:

1. A process for producing polymers of high molecular weight and soluble in lubricating oils. comprising subjecting substantially saturated oxygen-containing material characterized by a relatively long straight hydrocarbon chain and containing not more than one carboxylic group to a high tension electric discharge for a period suflicient to effect substantial polymerization.

2. A process according to claim 1, in which the said hydrocarbon chain contains at least 10 carbon atoms.

3. A process according to claim 1, in which the said material comprises a fatty acid of at least 10 carbon atoms.

4. A process according to claim 1, in which the said material comprises an ester having a straight hydrocarbon chain of at least 10 carbon atoms.

5. An improved process for producing polymeric alcohols, comprising subjecting an. alcohol to a high tension electric discharge for a period suillcient to effect substantial polymerization.

6. An improved process for producing polymeric alcohols, comprising subjecting an alcohol in'liquid condition to high frequency, high tension electric discharge until substantial polymerization is efiected.

7. An improved process for producing polymeric alcohols, comprising subjecting higher alcohols having more than 10 carbon atoms while in liquid condition to high frequency, high tension electric discharge'while under reduced pressure and at temperatures below about 500 F. for a period of time to eflect substantial polymeriza tion.

,8. A process for producing polymers according to claim 1, in which a cyclic compound is subjected to the electric discharge with the said oxygen-containing material.

9. A process according to claim 6, in which the alcohol is polymerized along with a compound of cyclic structure.

10. A process according to claim 7, in which.

the alcohol is polymerized along with an aromatic hydrocarbon.

11. An organic polymer produced according to the process of claim 1.

12. A polymeric acid prepared by subjecting an unpolymerized substantially saturated fatty acid of at least 10 carbon atoms to silent electric discharge for a prolonged period.

13. A polymeric ester prepared by subjecting an unpolymerized ester having a straight carbon chain of at least 10 carbon atoms and having not more than one carboxylic group to silent electric discharge for a prolonged period.

' 14. A polymeric alcohol prepared by subjecting an unpolymerizedalcohol to silent electric containing not more than one carboxylic group,

to the action of a silent electric discharge for a prolonged period.

17. A composition according to claim 14, in which the alcohol is polymerized with a compound of cyclic structure.

'18. A composition of matter comprising a mineral lubricating oil and a polymeric material produced according to the process of claim 1.

19. A composition of matter comprising a mineral lubricating oil and a polymeric material described in claim 16.

20. A composition of matter comprising a mineral lubricating oil and polymeric alcohol prepared by subjecting an unpolymerized alcohol to the action of a high tension electric discharge for a time sufficient to efiect polymerization.

21. A composition of matter comprising a mineral lubricating oil and a polymeric alcohol prepared by subjecting unpolymerized alcohol in the presence of a compound of cyclic structure, to the action of a high tension electric discharge for a time sufflcientto effect polymerization.

22. A composition of matter comprising a mineral lubricating oil and a polymeric alcohol prepared by 1 subjecting an. unpolymerized alcohol containing at least 0 carbon atoms with a material of cyclic structure to the action of a high tension electric discharge for a time suificient to effect polymerization.

23. Process according to claim 1 in which the JAMES A. 'FRANCEWAY. Sn.,' Administrator of Estate of James A. Frcmoeway,

Jr.. Deceased.

GARLAND H. B. DAVIS.