US2241243A - Lubricating oil - Google Patents

Description

Patented May 6, 1941 LUBRICATING OIL Robert E. Conary and Harry V. Ashburn, Beacon, and Paul S. Stutsman, Fishkill, N. Y., assignors to The Texas Company, New York, N. Y" a corporation of Delaware No Drawing. Application March 25, 1939, Serial No. 264,118

12 Claims.

This invention relates to a lubricating oil, and particularly to a motor oil adapted for lubrication of the bearings and cylinders of internal combustion engines, such as automotive engines, airplane engines, Diesel engines, and the like.

The modern development of internal combustion engines with extremely small clearance between piston and cylinder wall, together with the modern development of highly solvent-refined lubricating oils for use in the crank cases of such engines, has given rise to the problem of socalled varnish or lacquer formation. This yarnish generally appears as a yellowish or reddish brown film which deposits upon the metal surfaces, including the piston rings and skirt, and cylinder wall during operation of the engine over extended periods of time. In the newest engines having extremely small clearances and high compression, the building up of this varnish film increases the frictional resistance to the reciprocation of the pistons, thereby raising fuel consumption and reducing power output; and this deposit may become so severe as to frequently result in seizure of the pistons when the motor is stopped and allowed to cool.-

Further, the modern development of the highly refined motor oils together with the modern development of the new type bearings, including the connecting rod and main bearings of internal combustion engines, which has involved a departure from the old Babbitt bearings and has given rise to the new alloy bearings of the type oi cadmium-silver, copper-lead, cadmium-nickel,

and the like, has also presented the industry with It is a further object of this invention to provide such a lubricating oil containing an additive which is of such character as not objectionably I toeffect, or even to improve, other desirable properties and tests of the motor oil, particularly stability in storage and servicer resistance to oxif dation and sludge formation, demulsibility, reduction in oil ring and compression groove deposits with prevention of ring sticking and reduction in piston and cylinder wear. I

We have discovered that a mineral lubricating oil of the motor oil type, such as a modern highly solvent-refined lubricating oil, can be converted to one having exceptional ability to accomplish the objects set forth above by the addition thereto of a small proportion of an oil-soluble phosphite ester of an alkyl ether of an alkylene glycol having the general formula:

where X1 is an alkyl-alkylene oxide radical of the type:

- R3(OR4)n1(OR5)n2 where R; is an alkyl radical having less than nine carbon atoms and including the alkyls from methyl to octyl, R4 and R5 are the same or different alkylene radicals (CnHZn) selected from the group consisting of ethylene and the propylenes, m is 0 or i, and n2 is 1 or 2; and where X: and X3 represent either hydrogen or the same or difierent alkyl-alkylene oxide radicals of the type of X1 above. By the expression alkylene radical as used herein, it is'to be understood that this includes the ethylene radical H H C C H H and the two propylene radicals H H H H H ,-o-c-cand o-o H H H H HcH H HOCH'zCHzCHzOI-I are included, as well as the corresponding polypropylene glycols. These polyglycols are formed by the condensation of one or more molecules of 1 ethylene oxide or propylene oxide with ethylene or propylene glycolrespectively. In general, we prefer those compounds which are phosphite esters of the mentioned alkyl ethers of glycols,

or polyglycols which contain not more ,than two added ethylene oxide or propylene oxide groups to an ethylene glycol or propylene glycol group respectively. The higher members of this series having more than three condensed group-agenerally have such high boiling points and are so diflicult of separation'as to render them of lesser value for purposes of the present invention.

The mono-alkyl ethers of mono-ethylene glycol have-become familiarly known as Celloinvention, there are mentioned butyl "Carbitol phosphite, which is the tri-substituted normal phosphite ester of the mono-butyl ether of diethylene glycol having the following formula:

, and methyl Cellosolve" phosphite which is the tri-substituted normal phosphite ester of the mono-methyl ether of ethylene glycol having the following formula:

CHi.O.CH:CHz-O CH:.O.C H:.CHr-OP CH:.O.CH:.CH2O

These phosphite esters of alkyl ethers of alkylene glycols and their'method of preparation are disclosed and claimed in the copending application, Serial No. 264,119, of Robert E. Conary and Harry V. Ashburn, filed March 25, 1939. For purposes ofillustration, this invention is described in connection with the use as an additive of butyl "CarbitoP phosphite and methyl Cellosolve phosphite, although it is to be understood that .the invention is ..not limited thereto. The butyl Carbitol phosphite was prepared by the addition of one mol of phosphorus trichloride to three mols of dry mono-butyl ether of di-eth'ylene glycol, in the presence of an excess equivalent to about 3.3 mols of dry pyridine and approximately an equal weight of dry-benzene. The phosphorus trichloride was added dropwise to the mix of the butyl ether of di-ethylene glycol,

pyridine and benzene, with adequate stirring while the temperature was held at about 23-50 F. After complete addition of the phosphorus trichloride, the mixture was allowed to warm up to room temperature, then heated to boiling and refluxed for about two hours. After cooling to room temperature, the mixture was washed with cold'water until the wash water gave no acid test to litmus. The mixture was then dried over anhydrous sodium or calcium sulfate, the remaininf, p ridine, benzene and unreacted Carbitol removed by distillation under vacuum, and the desired product was obtained by vacuum distillation, passing over at approximately 455-465 F. under an absolute pressure of about 15-20 mm. mercury.

The methyl Cellosolve" phosphite was obtained by a similar procedure, substituting the mono-methyl ether of ethylene glycol for the mono-butyl ether of (ii-ethylene glycol in the procedure outlined above, except that in this case the washing step with water and the drying step were omitted, and the mixture after refluxing and cooling was filtered to remove the precipitated pyridine hydrochloride. The methyl Cellosolve" phosphite was obtained by vacuum distillation of the filtrate, passing over at approximately 290-305 F. under an absolute pressure of about 10-20 mm. mercury. Both phosphite materials are oily colorless liquids soluble in lubricating oil.

The additive is added to the mineral lubricating oil in a proportion of about Mil-2.0% by weight, and preferably of the order of 01-05% by weight. The material dissolves readily in the lubricating oil at room temperature with agitation, but its-solution maybe facilitated by heating the oil mildly. It apparently forms a stable solution which is not subject to separation, precipitation or sedimentation in storage or under service conditions, and is not volatilized or lost in service conditions normally encountered in crankcase lubrication.

A rigorous test which is used to determine the effectiveness of additives to stabilize lubricating oilsof this type against oxidation and inhibit varnish formation and bearing corrosion is the so-called Underwood Oxidation Test, which is described in a pamphlet dated August 1, 1938, of the Research Laboratories Division of the General Motors Corporation, entitled Underwood Oxidation Testing Apparatus." This test briefly consists in abrading the inside or concave surface of half of a standard cadmium-silver automotive bearing by a motor-driven wheel covered with abrasive cloth until an evenly scratched surface is obtained. A copper strip 10 inches grams.

long by 2 inches wide is also abraded by sanding until an evenly scratched surface is obtained. The strip and bearing are cleaned by washing in solvent (9. mixture of equal parts of denatured ethyl alcohol, toluol, and ethyl acetate), dried and weighed. The copper strip and bearing are then immersed in the oil to be tested in a box or troug-h equipped with pump recirculation for continuously circulating the oil over the bearing and strip, the app ratus having previously been carefully cleaned. The recirculating oil is heated to a temperature of about 325 F. and maintained at this temperature during the period of test of fifteen hours. This test as described is preferably modified by adding a small proportion of the order of 0.01% of iron oxide as iron naphthenate to the oil undergoing the test in order to catalyze the oxidation and-bearing corrosion, and to' more closely simulate the conditions encountered in crankcase lubrication where the oil is in contact with iron.

A sample of the oil undergoing test is withdrawn at 5-hour intervals, and likewise the bearing and copper strip are removed at 5-hour intervals, carefully cleaned, and weighed and again re-immersed in the oil bath At the conclusion of the 15-hour run, the copper strip is removed,

soaked for about ten minutes in. precipitation naphtha to remove adhering oil, dried and weighed. The increase inweight is recorded as weight of varnish accumulation. The test bearing is likewise removed, carefuliy cleaned with solvent which is effective to'remove both oil and the varnish film, dried and weighed, and the loss in weight is recorded as bearing corrosion in The samples of oil from the two intermediate 5-hour periods and from the end of the run are tested for Saybolt Universal viscosity at oil containing the desired proportion of the additive.

The following are the results of a catalyzed Underwood Oxidation Test on a furfural-refined dewaxed Mid-Continent distillate lubricating oil of S. A. E. 10 grade, and the same oil containing 0.25% of the butyl "Carbitol phosphite prepared as set forth above:

Blank oil+ To Blank 0.25% butyl oil "Carbitol" phosphite Percent iron oxide added as iron naphthenate. 0. 01 0.01 Neutralization number, 15 hours 19.9 3. 6 Bearing corrosion, grams, 15 hours... 2.172 0. 031 S. U. viscosity 130 F., initiaL. 94.5 94. 5 S. U. viscosity 130 F., 15 hours 575 123. 5 Percent incrcasein viscosity 508 30.7 Varnish deposit, mg 59 20 The above tests indicate very pronounced superiority of the compounded oil over the blank Blank 011+ Tcst Blank 0.25% methyl oil Cellosolve phosphite Percent oxide added as iron naphthenata 0. 01 0. 01 Neutralization number, 15 hours 45. 3. 36 Bearing corrosion, grams, 15 hours. 1. 488 0.000 Percent naphtha insoluble, 15 hours 13.03 0. 49 Percent chloroform soluble, 15 hours... 12. 0. 44 Percent Conradson carbon, hours 5. 44 0.70 S. U. viscosity 130 F., initial 94. 5 94. 5 S. U. viscosity 130 F., 15 hours 1700 126. 5 Percent increase in viscosity; 1800 33. 8 Varnish deposit, mg 42 15 The above tests indicate very pronounced surolet engine operated on ablock for thirty 'hours at an equivalent of fifty miles per hour, or 1500 miles, with a crankcase temperature of about 290 F. for an S. A. E. oil, and about 275 F. for S. A. E. 10 oil, with a jacket temperature of 212 F and crankcase ventilation of one cubic foot pm minule. A series of test was run on the same engine under these conditions, using for crankcase lubrication a turfural-refined dewaxed Mid-Continent distillate lubricating oil of S. A. E. 20 grade in comparison with the same oil containing a small proportion of an additive heretofore known to us as being very effective for varnish deposit inhibition, and termed herein for purposes of description a compounded S. A. E. 20 oil"; and another series of tests was run on a furfural-refined dewaxed Mid-Continent distillate lubricating oil of S. A. E. 10 grade containing the same proportion of said last mentioned additive, and termed herein for purposes of description a "compounded S. A. E. 10 oil, in comparison with the same S. A. E. 10 oil (uncompounded) to which was added 0.25% of butyl Carbitol phosphite for one test, and 0.25% of methyl Cellosolve phosphite for another test.

At the completion of each run, the engine was taken down, the pistons removed, and the varnish deposit determined on the oil rings and the piston skirt. washing first with precipitation naphtha to remove retained oil, then washing with acetone to remove the acetone-soluble portion of the varnish which is found to represent the bulk of the varnish deposit, then evaporating this acetone solution to dryness, extracting the residue with precipitation naphtha to remove remaining traces of oil, again taking up in acetone solution and filtering to remove suspended carbon particles and. impurities, and finally evaporating the acetone solution to dryness. residue is expressed as mg. of varnish deposit and represents the combined deposit of the piston skirt and oil rings. The following results were obtained:

I Varnish Crankcase oil tested deposit in mg.

827 Com unded S. A. E 20 oil 315 Bla S. 20 oil 701 Com unded S. A. E 20 Oil 95 Blan S. A. E. 20 oiL. Compounded S. A. E. 10 oil S. A. E. 10 oil+0.25% butyl "Car itol" phosphi c Compounded S. A. E. 10 oil Compounded S. A. E. 10 oil S. A. E. 10 oil+0.25% methyl "Gellosolve" phosph1te Compounded S. A. E. 10 oil These tests show that the compounded oil is greatly superior to the uncompounded oil, and further show that the butyl Carbitol phosphite and the methyl "Cellosolve phosphite of the present invention are markedly better than the previously known additive which was employed in the compounded 011 tests for purposes of com- 1 parison. In explanation, it may be stated that a lighter lubricating oil of S. A. E. 10 grade for example, generally gives a greater deposition of varnish than a heavier lubricating oil of the same same pro-- This was accomplished in each case by I The weight of the the same oil containing 0.25% methyl Ccllosolve" phosphite.

The compounded oils of the present invention also meet the Navy emulsion test, as determined by the United States Government test No. 320.12 as found on pages 76 et seq. of appendix 6, Lubricants and Liquid; Fuels," issued by the Navy Department August 1, 1928, with specifications set forth on page 7 of Naval Engineering Bulletin 31, Lubricating Oil" published by the United States Government Printing Omce in 1937. Briefly, these specifications require that an emulsion of lubricating oil having a Saybolt Universal viscosity at 210 F. in excess of. 55 seconds with water at 180 F.. or with a 1% NaCl solution at 180 F.. shall break in less than sixty minutes. The following tests indicate the effectiveness of the above noted reference 8. A. E. 30

oil compounded with 0.25% butyl Carbitol phosphite, and the same oil compounded with 0.25% methyl Cellosolve phosphite in meeting these specifications in comparison with the uncompounded' reference oil:

Reference 2 2 3 3? Reference fil i g oil+0.25% 'lcst S. A. E. b 1 methyl 30oll Y Celloarbitol Solve" phosphlw phosphitc Water emulsion at 180 F.,

time of complete separation in minutes 30 7 A 1% NaCl emulsion at 180 F., time of complete separation in minutes 15 10 7 Obviously, many modifications and Variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1 1. A lubricating oil comprising a mineral lubricating oil containing 0.01-2.0% by weight of a phosphite ester of an alkyl ether of an alkylene glycol of the formula where X1 is an alkyl-alkylene oxide group of the type 1 RsORi) 11.1(OR) 112 where R3 is an alkyl radical selected from the group consisting of methyl, ethyl, propyl, butyl. amyl, hexyl, heptyl and octyl, where R4 and R5 are alkylene radicals (CnHZn) selected from the group consisting of ethylene and propylene, where m is 0 or 1, and where m is 1 or 2. and where X2 andXs represent substances selected from the group consisting of hydrogen and alkyl-alkylene oxide radicals of the type 0 X1 above.

2. A lubricating oil according to claim}. in which the additive is a phosphite ester of an alkyl ether of a glycol selected from the groupconsisting of monoand poly-ethylene glycols. 3. A lubricating oil according to claim 1, in which the additive is a. phosphite ester of an alkyl ether of a glycol selected from the group consisting of monoand poly-propylene glycols. 4. A lubricating oil according to claim 1, in which the additive is a phosphite ester of a butyl ether of di-ethylene glycol.

5. A motor oil for lubricating the bearings and cylinders of an internal combustion engine comprising a mineral lubricating oil within the motor oil viscosity range containing (Mil-2.0% of a tri-substituted normal phosphite ester of a mono-butyl ether of di-ethylene glycol.

6. A lubricating oil according to claim 1, in.

which the additive is a phosphite ester of the methyl ether of ethylene glycol.

7. A motor oil for lubricating the bearings and cylinders of an internal combustion engine comprising a mineral lubricating oil within the motor oil viscosity range containing 0.01-2.0% of a tri-substituted normal phosphite ester of the mono-methyl ether of ethylene glycol.

8. The method of lubricating bearing surfaces of an internal combustion engine, which comprises maintaining between the bearing surfaces.

where X1 is an alkyl-alkylene oxide group of the type R3(OR4)n1(OR5)n2 where R3 is an alkyl radical selected from the group consisting of methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl and octyl, where R4 and R5 are alkylene radicals (CnHZn) selected from the group consisting of ethylene and propylene. where m is 0 or 1 and where n: is 1 or 2, and where X: and X1 represent substances selected 7 from the group consisting of hydrogen and alkylalkylene oxide radicals of the type of X1 above.

9. The method according to claim 8, in which the mineral lubricating oil contains Gill-2.0% by weight of a phosphite ester of a butyi ether of (ii-ethylene glycol.

10. The method according to claim 8, in which the mineral lubricating oil contains 01-05% by weight of the tri-substituted normal phosphite ester of the lnono-butyl ether oi di-ethylene glycol.

n i .l.a.lmllmammalian. i v M 2,241,243 f5 ..11.1 'rhe -mmdd accnrding to claim anlmeu' 0.1- 0.5%-b wighfioffih trl-substihitd normal the mineral lubricating 011 contains about '"phpsphitje ester of the '.,mon0-meth'y1;flether o2 1+2-0,% y Wgightoia' phosphite ester of the ethyleneiglyqol. methyl ether ongtlgylene glycol.

ROBERT 'nfcofimt.

the mmemlmbficatm on cpntgins abut H aAm. 8.8mm.

'ciaamIFIcAm 0 CORRECTION? '--m 6.19l;1.v ROBERT 1?. com, mm; certified that error appears'1'n fi1e printed s ec fuation w finibe'red p ateni: requiring cori-eetiofi as follows {Page 5,' f1 rst coliiminQi ,in the'table, befpi'e f'oxide insert '1ron-; pag'5'5 first [claim 11 f r or? read or; Qhd'fihait the said Lette s Pt riifread with this dorrectibn ihereir; fliat the same may 1- rbimhwfi 'ecbzd r th ease in; the Patntl Off1 ce.'-

"si izg aq nqs yied this 24th day r June, A.. .-D. 91p.

- Henry .Van Arsdale "(593 11) Acting cplimissioner of P'ateht CERTIFICATE OF CORRECTION. Patent No. 2,241,215. may 6. 1914.1.

ROBERT E. comm, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered piatent requiring correction as follows Page 5, first column, iine I47, in the table, before "oxide" insert --iron--; page'5, first column, line 1 claim 11, for "or" read of--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 214th day of June, A. 1). 191m.

Henry Van Arsdale (Seal) Acting Commissioner of P'atent