US2257601A - Method of lubrication - Google Patents

Description

' Patented Sept. 3Q, 19%? m'rnon or ruanrcsrron Frank W. Hall, New York, and Charles C. Towne, Beacon, N. Y., assignorsto The Texas 60m pany, New York, N. Y., a corporationoi' Delaware No Drawing.

2 Claims.

, 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.

One of the principal objectsof the invention is to provide an improved lubricating oil of this where R and R are similar or dissimilar fatty acid radicals such as those derived from stearic, palmitic, oleic acids, etc., and where X represents an amino alcohol group. In the case of lecithin, X ,or the amino alcohol group is ch0line'-CHzCH2N(CH3)3QH; and in the case of cephalin X is colamine- CHzCHzNHz. Other types of compounds falling within the class of phosphatides' can be employed such as sphen;

gomyelin.- Also metal derivatives or salts of the lecithins can be employed.- For example, the,

free acid group of the compound can be neu- Application August 6, 1938, Serial No. 223,487

(Cl. 25H, 3)

tralized with alkali, alkaline earth and other bases to form the corresponding salts thereof.

A preferred composition for this purpose is commercial soybean lecithin, such as the product known commercially as Lipoidol which consists essentially of about equal proportions of lecithin'and cephalin with a smaller proportion of soybean oil. In some cases it isfound preferable to employ a bleached commercial soybean lecithin, such as'the product sold commercially as Coloidol BT which is commercial soybean lecithin bleached with hydrogen peroxide and dlbenzoyl peroxide, or the product sold commerclally as "Coloidol HX" which is commercial soybean lecithin bleached with hydrogen peroxide. If desired, the commercial soybean lecithin can be purified by extracting the soybean oil with acetone to obtain a product consisting essentially of lecithin and cephalin, which is also suitable for the purposes'of the present invention. Also, the cephalin constituent can be separatod from the lecithin by alcohol extraction, and either the purified lecithin or purified cephalin or mixtures of the two in any desired proportion may be employed for purposes 01' the present invention; However, it has been found that the purified constituents do not display any marked improvement over the commercial soybean lecithin, and the latter is generally preferred for economical reasons. Another suitable commercial product for purposes of this invention is clearate which is a phosphatide compound, as defined above.

Wherever the expression phosphatide compound is used throughout the description and claims, it is to be understood that this includes any of the purified compounds or derivatives thereof falling within this group, as well as any of the comparatively impure mixtures such as,

the commercial grades mentioned above.

In accordance with the present invention, the phosphatide compound is added to the motor oil in a critical proportion range of about (Mil-2.0%. It is found that these percentages are critical in seeming the desired improvement with respect to inhibiting bearing corrosion and lacquer formation and without afiectin'g other desirable properties of the oil, while proportions above this range produce undue sludging. In the case of motor oils adapted for automotive use, a range of 0.01 to 0.25% appears most satisfactory, with about 0.1% preferred. Somewhat higher percentages may be employed in Diesel lubricating oils or airplane oils where it is desired to improve materially the ring sticking properties of the oil in addition topobtaining the benefits of inhibiting bearing corrosion and lacquer formation. A very satisfactory method for adding the phosphatide compoundto the mineral lubricating oil is to first form a concentrate, such as a. 50% solution or the lecithin or other phosphatide compound in a S. A. E. 30 oil or other lubricating oil within the motor oil viscosity range, and then add the concentrate to the mineral lubricating oil in an amount sumcient to give the desired percentage of phosphatide compound therein.

The additive of the present invention is "particularlyefl ective in connection with highly solvent refined lubricating oils, such as the modern motor oils which have been refined with a solvent the modern development of highly solvent re-' fined lubricating oils for use in the crankcases of such engines, has given rise to. the problem of socalled varnish or lacquer formation. This lacquer generally appears as a yellowish or reddish brown film which deposits upon the metal surfaces, piston rings and cylinder walls during opsmall clearances and high compression, this probproperties unrelated to the fiber wetting or film action of the prior art.

As illustrative of the etfectiveness of the phosphatio'e compounds of the present invention in merated, which are entirely new and unexpected lem is so severe as to frequently result in seizure reducing bearing corrosion. the following test was of the pistons when the motor is stopped and alused. A bushing lined with the same cadmiumlowed to cool. silver or other alloy as employed in connecting Further, the modern development of the highly rod hearings in some automotive engines, was refined motor oils together with the modern deimmersed in a pot of the oil to be tested, the oil velopment of the new type bearings including being heated to a temperature of the order of the connecting rod and main bearings, of inter- 325-350 F. The oil is'circulated between the 118.1 combustion engines, which has involved a bushing and its journal-by a suitable propeller departure from the old Babbitt bearings and has or whirligig" for a period of five hours. The given rise to new alloy bearings of the type of bushing is removed from the pot at intervals of cadmium-silver, copper-lead, and the like, has five hours, weighed and returned. The loss in also presented the industry with the problem of weight is expressed in milligrams and is consid bearing corrosion. This latter problem has been ered the corrosion loss. The reference oil emrecognized for the last several years, and variployed in these testswas a furfural refined deous materials have been heretofore suggested as waxed Mid-Continent lubricating 'oil of S. A. E. additives for lubricating oil to inhibit such beargrade.

Percent 1 Test oil suggail ce 10 hr. 15 hr. 20hr. fig Reference oil 100% blank 1 3,1 34,39 212,236 473,456 +Clearate BB 0.25 0 1 o o 4 a 6 5 a +Olearate BB with soyn bean o I removed 0. 25 l 1 2 3 4 5 9 9 +Cephain from Clearate 0.25 l 2 4 6 7 8 i 9 l0 +Leclth;.n from Clearate- 0.25 2 a 4 5 a o a a +Cl'lld6 Lecithin 0.25 1 3 4 5 5 e c 1 +Coloidol BT 0. 1 2 3 3 4 5 6 6 6 +Lipoidol. 0.1 5 s 10 11 11 11 14 2o ing corrosion. However, the materials hereto- From the above tests, it is noted that in the fore suggested and used for this purpose, suchcase of the reference 011 there is a short inducas triphenyl phosphite, are ineifective in overtion period of less than ten hours within which coming the more recent problem of lacquer forlittle corrosion takes place, but then the rate of mation. The phosphatide'compound of this incorrosion increases rapidly for the duration of vention is unique in combining in one substance the run up to twenty hours. However, in the the properties of preventing or minimizing this case of the reference oil blended with the phosobjectionable lacquer formation and of also in- 40 P d Compounds Specified, it w s noted hat hibiting bearing corrosion, reducing cylinder and very little corrosion took place over the entire piston wear, and improving'ring sticking of the period of the run which was extended to forty motor oil to which the compound is added in the hours. small proportion range specified above. The lacquer formation test thus far developed We are aware that it has been heretofore sugprimarily a qualitative one. This may be cargested to add lecithin together with a soap to a ried out by employing the oil in an engine havlight lubricating oil having a Saybolt viscosity of ing extremely small clearances of the order of less than 100 seconds at 100 F. to produce a tex- 5/ .000 to 7/ 10,000 o a inch and running the tile fiber spraying 011 (see U. S. Patent No. 2,002,- engine for an extended period of time with-fre- 885). The lecithin was employed here to imquent stopp a d cooling to test for piston seiprove the wetting or filming character of the oil zure, and finally insp 0! e Piston and cy for'the textile fibers. The present invention is inder wall after the termination of the test. In distinguished in the addition of lecithin to a the case of the reference oil, a furfural refined difierent type of lubricating oil (a motor oil dewaxed Mid-Continent distillate of S. A. E. 30 adapted for lubricating the bearings and cylin- 65 grade. pi n seizure y o r f q n ly after clers of an internal combustion engine) which is a run of comparatively short duration; and inof a different viscosity range as falling within pection of the parts will show the presence of the motor oil viscosity range and having 8. Sayan pprec a le cquer film. On the other hand, bolt viscosity in excess of 100 at 100 F. and gensimilar runs conducted with the reference 011 erally in excess of 1 50 at 100 F. By motor oil 0 c mpounded with about 0.1-0.25% of the phos viscosity range is understood that range embrac- Dhatide compounds specified above may be caring the motor oils falling within the S. A. E. 10 ried out satisfactorily wi Piston Se e. and to range as well as certain heavier motor oils spect-Ion will show the metal surfaces of the adapted for special use in heavy duty truck or Piston and y d Wall o be c p v y ree bus engines at higher atmospheric temperatures, of any la q e filmandhaving a viscosity range varying from about without ng tobe bound to any particular seconds at F. up to about seodhds at o y. it s e d that the p osn at des 210 F. Saybolt Universal, as shown on page 444 Possess an adso pt n a o in preventing lacof the 1936 edition of the s. A. E. Handbook. quer formatione t y such p osphatide The present invention is also distinguished from 70 p unds form a colloidal solution or colloidal the above mentioned patent in that the additive Suspension with l br at Oi hich is extremeis employed for an entirely different purpose of 17 Stable- For example, W lubricating O inhibiting lacquer formation andbearing corroci'mtalning lecithin Within the r ort on a e .sion in addition to the other advantages enu- .75 set out above is heated and oxidized at 350 F.

for eight hours in the Indiana oxidation test, the

. as triphenyl phosphite, partially separate from the oil under this test. This colloidal solution or suspension of lecithin is believed to provide a multitude of surfaces within the oil upon which the'lacquer particles are adsorbed as they are termed, and are thereby prevented from plating outon the metal parts-of the piston and cylinder wall. The fact that the colloidal solution or suspension so formed is not separated by filtration through the standard types of oil filters employed in automotive engines, after the compounded oll has been in engine service, shows that the lecithin or other phosphatide compound remains operative and efiective in an internal combustion engine over extended periods of time, so that its anti-corrosive andanti-lacquer forming properties are retained. Moreover, the lecithin functions to maintain a finer dispersion of such sludge as may be formed in the oil during engine operation.

Typical results on the Indiana oxidation test on the reference oil (a furfural refined dewaxed Mid-Continent distillate of S. A. E. 30 grade) and on the reference oil compounded with thenoted percentages of the phosphatide compounds are set forth in the following table:

sludge deposit, as is evident from the following runs made on an $02 refined pale lubricating oil having a viscosity.of 750 and 100 F., and on the same oil compounded with 1.0% of Lipoidol. In

this test, a single cylinder F. R. Diesel engine is employed, which is run for thirty-six hours at 1200 R. P. M. at 210 F. jacket temperature with an artificially enriched fuel mixture and a fuel rate of 26 cc. per minute. After the run, the engine is taken down, the dirty piston rings are weighed, then the rings are cleaned by washing in benzol, and the cleaned and dried rings again weighed. This gives the total deposit including solid material and oil in the oil ring slots. The

benzol is then evaporated to dryness, and the Glearate C e helm Lecitbm Material added Clem-ate gtg gi {Bum from ggggg,

removed Clearate Olearate .Oonc. percent 0. 25 0.25 0.25 0. 25 6.25

Original sample vis.

S. U. 210 F 63-63 63-63 62 63 62 62 0. 02-008 0. 04-0. 04 0. 04-004 0.04-0. 04 0.03-0.03 Sap. NO 0. 5 0. 5 0. 7-0. 7 0. 06-0. 05 0. 5 0 3-0- 6 Indiana oxidation 1 10 mg. point..- 74 18 i0 20 82 74 100 mg. point... 126 128 130 142 142 133 The above tests show that the addition of the phosphatide compound may reduce the time required to reach the ten milligram point, but in every case the time required to reach the 100 milligram point of sludge is increased, thus mdicating that the phosphatide is also efiective to reduce oxidation or sludging as determined by the Indiana oxidation test over an extended period of time. The reduction in the time to reach the ten milligram point is attributable to the sludging characteristics of the phosphatide compound or lecithin itself, and apparently is not due to any effect that the additive has upon the initial sludging characteristics of the lubricating oil. Moreover, most of this sludge so formed from the lecithin is of the colloidal type mentioned which is believed valuable in promoting the inhibiting of lacquer formation as discussed above.

Another problem which has more recently come to the fore, particularly in the case of Diesel engines such as those employed in tractors, is thatof a sludge deposit. in the compression ring grooves and in the oil ring slots of the piston and piston rings. It is found that these deposits may accumulate to such an extent as to cause stuck rings and scoring of the cylinder wall. I

The phosphatide compounds of the present in- The following is an example of typical results obtained in this test:

3 5 22??? Mg. oilnaphtha 2 free dcinsoluble singing posit in sludge in gmoves oil rings cmxgigftase Reference oil" H 459 323 76 Reference oil plus 1.0% Lipoidol I 321 129 .54

900 R. P. M. with 1 spark advance and wide open throttle, and again taken down and rings cleaned and weighed. This difierence in weight of the rings before and after the twenty hours of operation is computed as milligrams of ring wear.

The following results were obtained in this test on an acid treated and clay contacted Mid Continent distillate of S. A. E. 20 grade, and on Oil tested Ring wear Reference oil(average of two runs) 176 Reference oil plus 1.0% Lipoidol (average of two runs).

The above test shows a 32% improvement of the compounded oil over the base oil. The phosphatide compounds of the present invention are also effective in reducing ring sticking of a motor oil. To illustrate this effect, a test is employed using aC. F. R. single cylinder engine operating at 900 R. P. M. with a :1 compression ratio, with 1 spark advance and wide open throttle, the jacket temperature being maintained at 375 F. The engine is equipped with a cast iron solid skirt piston with conventional piston rings. In preparing the engine for testing, the crank case, cylinder and iston are first cleaned thoroughly to remove all deposits and to provide a perfectly clean engine. The engine is then reassembled and the crankcase'charged with the required amount of oil, generally 3000 c. c. The engine is then operated to give maximum power under the conditions set forth above for an interval of time, generally eighteen hours. The oil is then drained immediately after stopping, the

was required in the initial run on this oil. assumed that this means that engine conditions are changing over the period of the three runs. For purposes of -calculation, it 'is assumed that engine conditions which affect ring sticking change uniformly withrunning time over the three runs considered. The average sticking time for the reference oil is therefore not taken as the mean of the two reference runs, but is interpolated for the time at which sticking occurs with the test oil. The actual time required to stick the rings with the test 011 is then compared with this interpolated or bracketed average time for the reference runs and expressed as the per cent the test 011 is better or worse thanthe reference oil with respect to the time required to stick rings.

In a test of this type on a typical airplane oil and on this oil compounded with 1.0% of Lipoidol, the compounded oil showed a 125% improvement over the reference oil.

In addition to the advantages enumerated above,

it is foundthat these phosphatide compounds and.

particularly the purified compounds or the bleached commercial soybean lecithin can be added to high grade typical motor oils without objectionably affecting desirable properties or tests of these oils, as illustrated in the following table:

011 used Blank oil (furfural refined dewaxed Mid-Cont. Same ref. oil Same ref. oil Same rel. oil

dist. 0! S. A E

grade) Material tested Clearate Coloidol B'l Coloidol BT. Percent material .25 0. 1 0. 25.

or, F

Neut. N

Ash, percent T 0 Carbon residue, percent engine allowed to cool for at least three hours Obviously, many modifications and variations and then the cylinder removed and the piston rings inspected. If, upon inspection, the rings are found free, the cylinder and oil are replaced and the run continued for an additional eighteen hours, when it is again disassembled in the manner set out above and the rings reinspected. This procedure is continued until sticking occurs, generally of the top piston ring, or until the run has continued for such a length of time without actual sticking. If, at any inspection, rings are on the verge of sticking, the additional run may .be reduced to twelve hours or less. If any severe ring sticking condition is observed, the sticking time is estimated at some value between that 'of the final and the preceding inspection. An accuracy of plus or minus sixhours is generally obtained. No make-upon as added to the crankcase-during a complete run on any oil, as th 'sdsv foun'ijjo seduce"the"accuracy of the run.

Three rims are required tofiate an oil' being tested in comparisonwith a reference oil. The reference oil is run bcith-v before and after the test sample. It is often. found that a substantially different time to attai-n stuck rings is required in the finalrun on the reference oil than of the invention herein-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 ap-- bearing corrosion and vanish deposits while maintaining the effectiveness of the lubricating,- action by incorporating in the said mineral lubri cating oil about 0.01-2.0% of a phosphatide compound.

2. The method according to claim 1, in which the phosphatide compound is lecithin.

CHARLES C. TOWNE. FRANK W. HALL.