US2257627A - Lubricating oil - Google Patents

Description

Patented Sept. 30, 1941 LUBRICATING OIL Hans G. Vesterdal, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 29, 1937, Serial No. 182,253

8 Claims.

The present invention relates to improved lubricating oils and method of preparing the same. It particularly relates to highly refined stable lubricating oils which are suitable for use under the extreme oxidizing conditions prevailing in internal combustion engines as, for example, in motor, Diesel and aeroplane engines. This improved highly refined lubricating oil, which is highly resistant to oxidation and sludging, is prepared by treating refined lubricating oil with a small quantity of a boron halide.

It is well known that highly refined lubricating oils are very desirable for use in internal combustion engines. These oils, however, as a result of the extended refining processing steps are prone to oxidize more readily than less highly refined oils. One explanation of this is that the'refining steps tend to remove natural inhibitors present in the oil which are not removed in aless highly refined 'oil. The oxidation tendency of oil is aggravated when subjected to the high temperatures and extreme oxidizing conditionsprevailing in internal combustion engines. The oxidation of the oil results both in the formation of acidic substances which cause excessive corrosion and in the formation of oxidation products which are insoluble in the oil and consequently settle out in the form of a sludge. This resulting sludge formation greatly decreases the lubricating quality of the oil and may result in bearing seizure and engine failure. This tendency of a highly refined lubricating oil to oxidize may be overcome to a large extent by. the process of adding oxidation inhibiting substances. These oxidation inhibitors, while preventing undue oxidation of the oil, however do have the disadvantage in that most of them tend to increase the Sligh value of the oil. These substances have. the further disadvantage in that they must be handled separately and must be blended in the oil in the correct proportion.

The process of the present invention prepares an oxidation and sludging resisting highly refined lubricating oil by treating a highly refined or partly refined oil with a boron halide, preferably boron fluoride. The lubricating oils to be treated according to the present invention may be any lube distillate. The preferred stocks are lubricating oils which are mainly paraffinic in nature or oils which have been cresyl phosphate, aniline, acetone, and also low boiling liquid hydrocarbons as, for example, liquid propane and butane. Suitable materials to be treated according to the present invention are, for example, oils prepared by acid treating and dewaxing of so-called parafiin distillate which is secured from paraflin type crude, such as Pennsylvania crude, or by selective solvent treating of lube oil distillates from any kind of a crude oil, provided, however, that most of the unsaturated and aromatic compounds are removed by such pretreatment so that the oil to b treated with boron halide has a. bromine number of below 1, preferably below 0.5 and a gravity in the range from 24 to 35 A. P. I. and viscosities in the range from 75 seconds Saybolt at 100 F. to 200 seconds Saybolt at 210 F.

These refined lubricating oils'are treated with less than of boron fluoride, preferably with about .2% of boron fluoride. The conditions of treatment are preferably at room temperature and atmospheric pressure, although temperatures up to 300-400" F. may be employed. The preferred method is to mix the oil with boron fluoride at the desired temperature for one to 30 minutes. Longer time of contact may be used although 30 minutes generally is sufiicient. At the end of this period, the mixture is stripped with superheated steam or an inert gas at about a temperature of from 300 to 550 F. or vacuum stripped until all the corrosive compounds derived from the boron fluoride have been removed.

The following examples are given for the purpose of illustrating the invention and are not to be. construedas limiting the invention in any manner whatsoever.

Example 1 A paraflindistillate derivated from a paraffin l l a fiashof approximately 305 F. and a viscosity pretreated with a cheaperrefining agent such as sulphuric acid, aluminum chloride, or with selective solvents which have the ability to segregate hydrocarbons having a higher ratio of hydrogen to carbon from the hydrocarbons having a lower ratio of. hydrogen to carbon as, for example, dichlor ethyl ether and also liquid sulphur: dioxide, phenol, ortho anisidine, ethylene diacetate, triphenyl phosphate, acetonitrile, 1 furfur'al, resorcinol diacetate, tri- Saybolt of 72 at F., was treated in order to remove the wax constituents. The dewaxed oil was then led to a distillation unitin which the feed stock was flashed under high vacuum producing lubricating stocks having viscosities at 210 -F. of about 43 and 52 seconds Saybolt respectively. This latter fraction having a gravity of approximately 25 A. P. I. and a flash of approximately 450 F. was then treated with approximately an equal quantity of phenol. The resulting lubricating oil had a gravity of approximately 30, a flash of 450 F. and a viscosity at 100 of about 312.

A portion of this refined oil was treated with about 0.5% of boron fluoride at room temperature with suitable agitation. This saturated material was then treated with preheated steam at atemperature of from 330 to 350 F. to remove the boron fluoride. This treated oil was then tested for sludging tendency as measured by the Sligh value* as well as a sample of the oil which was not treated with boron fluoride.-

The results were as follows:

Sludge determination igh value I y Mg. sludge/ g. of oil Boron fluoride treated oil 2.5 Untreated. oil V 7.8

*Sligh test: A method for determining the sludglng tendency in a lubricating oil described' m an A.' T. M. Report Committee D2, page 22, 1927. The Shgh test on the'above samples was modified in that it was run over a period of 24 hours instead of the 2 ,4; hours described in the report.

at room temperature with suitable agitation.

This mixture was then h eated to a temperature of about 300 F. and was steam stripped. at a temperature of about 300 to 350? for a period or about minutes. The sludging tendency of the boron fluoride treated oil was determined as well as the sludging tendency of the untreated oil. The results were as follows:

Sludge determination Sligh value Boron fluoride treated oi1 2 4 Untreated oil 21.5

E rahtple 3 V 'The lubricating 011-a 'r::smiii151e 2 was mixed with 0.06 gm. of boron fiu rideperiOO cc. ofoil at room temperature for 15 minutes. The mixture was then steam stripped at 330 to 350 F.

for 15 minutes. The sludg'in ten denicy ofithe treated and untreated oils was dete'rniineda's be-.

fore: a

" Sludge determination Sligh value Boron fluoride treated oil 3.8 Untreated oil .21.5

Example 4 V o c'c. 01" the lubric ating loil of gamma 2 were mixed with 0.3 gram of boron fluoride at 250-260" F. for about 5 to 10 minutes. The mixture'was heated up' further and steam stripped at 330-350 F. for 15 minutes. The sludging tend! any of the treated and untreated oils was determined as before, as well as the viscositie s at '100" F. and 210 F, (and viscosity indices):

The lubricating oil or Example 2 was mixed with 0.5% boron fluoride at room temperature for approximately .l ,rninutes. I, The mixture was & ences.

then steam stripped "at teni'peratui'e'sfro'r'n "330 to 350 F. The sludging tendency of the untreated oils was determined as described above.

Sludge determination Sligh value 1 Boron fluoride treated oil 2.4

Untreated oil 21.

Example 6 The boronfiuoride treated oil as described in Examples 3, 4 and 5, and the untreated oil, were tested in order to determine their oxidation rate. The results of these tests were as follows:

Oxidation Bromine rate) No.

Untreated oil 181 0.03 Oil treated withi 0.5% boron fluoride 172 0.15% boron fluoride i 0.06% boron fluoride .i

*A test to determine the tendency oi the oil to oxidize. Oilis bubbled in a closed circulatory system through 10 cc. 01 the respective oils which are held at a temperature of 200 C. At 15 minute intervals the amount of oxygen remaining unconsumed is measured,

and the volume of oxygen absorbed by the oil calculated by difier ings. V

Example 7 200 grams of a well refined, motor oil (S. A. E.- 30) which had excellent qualities except for its high Sligh value, were mixed with less thanp0.1 gm. of boron fluoride. at room temperature for itminutes. The mixture was heated up to 350 F. and steam, strippedfor 15 minutesat this temperature. vThe sludging tendency of the treated and untreated oils was determined as before: n i y H Sludge determination f Sligh value Boron fluoride treated oil Untreated oil V Ezcdmple 8 A lubricating motor oil S. A. E. 30 was tested to determine the oxidation rate and the sludging tendency as measured by' the Sligh number as wellras by the Cone test. To this oil. was then added 2% of natural inhibitors which tend to decrease the oxidation rate. The oxidation rate and Sligh value were determined on this blend; The blend was then treated with 0.3% of boron fluoride in the manner described above and the same tests were then made. The results wer'e' as follows: i

-Oxida- Sludging Zion en e y 91 rate Sligh No. es

Lubricating oil 8. A. E. so 1. 2 '0. 88 Lubricating oil S. A. E. 30 2% natural inhibitor as 48.6 Blend treated with 0.3% boron fluov ride V 6 43.9 0.30

r *A method for determining the tendency of an oil to deposit-sludge matter upon a heated metalllc' surface. It. consists in slowly droppine the 011 to be tested over a heated metal cone which is generally steel. The cone has a circumferential groove-milled out in a screw fashion on the periphery thereby allowing a time of contact of about one minute between the heated steel surface and the oil. Atot'al volume of 60 cc. of oil is released from a dropping funnel'ov'r a period of two hours. V

desired value but for lubricating oils it is preferred to fuse 'about'250 0. since 1t represents approximately the extreme temperatureto which oils are ordlnarily exposed in the internal combustion engine.

After the entire volume of oil is run over the metallic surface the cone ldWaShed with naptha to completely remove the adhering oil without d sturbing the deposit left on the cone. The cone is then weighed and the ncrease in weight of the cone due'to the depositleft thereon by the 011 is expressed in grams. 1 e

r V I Emapze 9; e r

A 'lii ris atih soi as a mament 11 was mixed with approximately 10% of a mixture The above oxidation rate is an average 01 the first three read- The temperature of the cone may be any of di and tri isobutylene. The unblended oil was treated with 0.5% boron fluoride and the blend was treated with approximately of boron fluoride. The sludging tendencies of both the untreated and treated oilswere then determined with. the following results:

% di and tri isobutylene 100% lubri- 90% lubricateating oil eating oil Sligh No. on untreated oil 7.8 Sligh No. on treated oil 9.8 2. 5

It is particularly applicable to the preparation of high grade motor oils, of electrical transformer oils and the like. If necessary, the oils may be dewaxed before or after the boron fluoride treatment and/or they may be treated either before or after the boron fluoride treatment with other reagents such as sulphuric acid, aluminum chloride, clay or other treating agents, or with selected solvents such phenol, chlorex, nitrobenzene and the like, or with light hydrocarbon solvents. Asphaltic and oxygen-containing materials are preferably removed before the boron fluoride treatment.

The invention is not to be limited by any theory or method of operation but only by the following claims in which it is desired to claim all novelty in so far as the prior art permits.

I claim:

1. Process of preparing improved oxidation and sludging resistant lubricating oils comprising treating a previously refinedlubricating oil substantially free of unsaturated materials with a small amount of a boron halide in an amount less than 0.5%.

2. Process in accordance with claim 1 in which said boron halide is boron fluoride.

3. Process of preparing improved oxidation and sludging resistant lubricating oils comprising treating a refined lubricating oil substantially free of unsaturated materials and characterized by having a bromine number less than 1 with a small quantity of boron fluoride in an amount less than 0.5%.

4. Process in accordance with claim 3 in which said bromine number is less than 0.5.

5. Process of preparing improved oxidation and sludging resistant lubricating oils comprising treating a refined lubricating oil substantially free of unsaturated materials and characterized by having a bromine number less than .5 with from 0.01% to 0.5% of boron fluoride for a sufiicient length of time to increase the stability of the said oil, followed by stripping of the treated product to remove the boron fluoride and corrosive compounds.

6. The process of preparing an oxidation and sludge resisting highly refined lubricating oil comprising treating a paraflinic base oilof lubrieating oil consistency to remove wax constituents, flashing the dewaxed oil under high vacuum, treating the distillate fraction with ap-.

proximately an equal quantity of phenol, removing the raflinate fraction and dephenolizing it, treating the resultant raflinate oil with a small quantity of a boron halide in an amount less than 0.5% for a sufficient period of time to increase the stability of the said oil and stripping the treated product to remove boron fluoride and corrosive compounds.

7. Process according to claim 6 in which the amount of boron fluoride employed is between 0.01% and 0.5%.

l 8. Process for preparing an oxidation and sludge resisting highly refined lubricating oil comprising subjecting a lubricating oil fraction of a crude petroleum to a refining treatment to produce a refined oil having a bromine number below 1, a gravity between 24 and A. P. I., and a viscosity between seconds Saybolt at F. and 200 seconds Saybolt at 210 F., then treating said refined oil with a small amount of oil to remove boron fluoride and corrosive compounds.

HANS G. VESTERDAL.