US2311305A - Method of producing lubricating material - Google Patents

Description

Patcnted Feb. 16, 1943 STATES, PATENT OFFICE METHOD or PRODUCING LUBRICATING MATERIAL Harold W. Ritchey, Long Beach, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application May 6, 1940, Serial No. 333,605

19 Claims.

This invention relates primarily to the manufacture of lubricating oils, and the particular object is to produce lubricating oils having high detergent characteristics for the elimination or prevention of the formation of gummy, resinous,

and varnish-like materials that tend to form in severe service internal combustion engines and to deposit upon pistons, piston rings and the like. Other objects of the invention include easy production of additive materials employed in mineral lubricating oils to produce lubricants of the mentioned type. Another object is to produce such lubricants with high film-strength characteristics. Another important object is to furnish suitable processes and materials for producing motor lubricating oils the indicated type from lubricating oils of high viscosity index as represented by the so-called highly parafilnic lubrieating oils. Subject matter disclosed herein' but not claimed is claimed in my companion application Serial No. 353,377, filed August 20, 1940, entitled Phosphonic acids. 1

Not all mineral lubricating oils as they are initially refined under modern refining methods are wholly adapted to some of the uses for which they are-intended, and apparently no such lubricating oil is adapted for use under severe service conditions such as use in Diesel engines and high out-put aviation engines. Such oils need modification, as by addition of modifying agents. Some lubricating oils, and particular reference is made to mineral lubricating oils of high viscosity index (V. 1.), need modification to increase their film-strength and also to improve their tendency to deposit gummy, resinous, and varnish-like material in the engine, particularly upon the pistons and rings as above indicated. Most lubricating oils, including the oils of high viscosity index (namely the so-called highly paramnic mineral lubricating oils) require additives to adapt them to serve service uses in order to increase their film-strength and to overcome excessive tendencles'towards deposits in the engine as mentioned.

high viscosity index (that is well-refined oils of the so-call'ed highly parafflnic type possessing minimum tendency towards viscosity fluctuation), of oil-soluble salts (or soaps) of phosphonic acids produced by phosphorizing the socalled highly parafilnic mineral lubricating oil fractions (high V. I. oils), and then oxidizing or air-blowing the resulting phosphorized materials to produce phosphonic acids from which the salts are formed. The invention further resides in This applies not only to parafilnic type oils but also to naphthenic type or so-called Western or asphalt base oils. More recently it has beenlparticularly desired to adapt oils of high viscosity. index to Diesel engine uses and other severe service uses: (The term fvisc'osit'y index iswell understood in the arts and is defined in Chemical and Metallurgical Engineering, volume 36 (1929) page 618 in an article by Dean and Davis.) Quite commonly, where additives have been introduced into lubricating oils to attain these ends, corrosive conditions have been developed in the engine probably by catalytic influences of the additive. This has been especially noticeable where highly corrosion-sensitive bearings have been employed J in Diesel engines. The result has often been that such bearings have failed. For example, in the the incorporation into such a mineral lubricating oil of calcium salts of such phosphonic acids or substantially equally oil-soluble salts of such phosphonic acids of which salts or soaps formed with another alkaline earth metal such as magnesium or barium might be given as examples. The invention applies particularly to such an oil where the proportion of the soap is in the order of about one-half per cent to about 3% or in quantity sumcient to produce the desired detergent characteristics and at the same time not impart to the oil any appreciable viscosity in-' crease.

I have discovered that the use of oil-soluble phosphonic salts or soaps of the type described.v

when used in proportions around 1% based on the oil have the property of controlling the deposition of gummy, resinous, and varnish-like or lacquer-like materials upon the walls of pistons and about the rings and similar parts of internal combustion engines including Diesel engines and other severe service engines. I have also discovered that these salts exert noappreciable oatalytlc influence towards the oxidation of lubricating oils and the formation of corrosive acids as is sometimes-the case when soaps of other forms of acids are employed, suchas carboxylic acids. Also soaps of the present type possess neutralizing characteristics or'at least a tendency to maintain non-corrosive conditions insofar as their efiect on highly sensitive bearings and the like is concerned. This may be due to the fact that the metal element of the salt or soap may combine with any corrosive acids that might possibly form and thereby liberate the non-corrosive phosphonic acids which in turn' appear to exert corrosion-inhibiting influences kindred to corroi phorus may be attached to naphthenic rings or phorussufllcient to give it a yellow color.)

there is no decomposition of the phosphonic salts or soaps and they maintain their form which continuously exerts said influences tending to inhibit development of corrosive conditions.

The materials particularly used under this form of the invention are obtained from phosphorizing mineral lubricating oil fractions of so-called highly-parafilnic character or of high viscosity in index. According to the best modern authorities on the constitution of mineral lubricating oil 0! this type, the molecules are not primarily aliphatic or chain compounds but are mixed or complex molecules containing aromatic or naphthenic rings protected by aliphatic or parafllnic side chains which may in themselves be straight chains or branched chains. Or such oils may be mixtures of molecules wherein aromatic or benzene rings are protected by aliphatic chains and wherein naphthene rings are protected by aliphatic chains. On phosphorizing'these materials the phosphorus grouping apparently enters more readily to replace a hydrogen atom connected to one of the carbons oi the aliphatic chain; This phosphorus grouping apparently maybe connected either to an end carbon of the chain portion of the molecule or to an intermediate carbon of said chain portion, and the phosphorus grouping of the resultant phosphonic acids apparently has the arrangement:

0 -o -r on OH However, while there seems to be ample evidence that this is the structure, I nevertheless do not wish to be bound in all events by this theory. It is possible also that a portion of the total phosto aromatic rings, when such .are present.

In phosphorizing mineral lubricating oils. Preparatory to oxidizing the phosphorized materials .to yieldthe phosphonic acids, I have employed different procedures. According to one procedure the oil itself is heated to incipient crackins" or decomposition and yellow phosphorus lumps re added with heating at appropriate temperatures such as up to about 600 F. until the phosphorizing reaction iscomplete. (Yellow phosphorus is the commercial term for white phosphorus which ordinarily contains small quantities of red phos-' In this instance, a nitrogen,.ca rbon dioxide, or other inert atmosphere may be employed for safety purposes. According to another operation the mineral oil is first chlorinated to facilitate subsequent phosphorination. This may be done by bubbling a chlorinegas therethrough until the weight is increased by chlorine addition to an extent of perhaps l0% but preferably less. Only I 2% has been used in these examples. This mate= rial after a suitable was ing is then phosphorized by heatingfor approp iate periods to incipient cracking" or decomposition with addition of yelas low phosphorus lumps until suitable phosphorination is produced. In this case lower temperatures such as a maximum of about 475 F. will sufilce. Following phosphori'zation for an appropriate time, for example one to three hours, the charge is cooled to about 200 F. for example, and air then passed therethrough at. a slow enough rate to prevent temperature rise much about 250 F. W hen the oxidation reaction ceases to promote temperature increase, further air-'75 blowing may or may not be resorted to, but it continued for the purpose oi insuring sufllcient or further oxidation the air-blowing may be extended for a suitable time, for example about one hour, at a higher temperature, for example at about 300 F. In all cases, air-blowingshouldbe.

carried out in a manner to attain 'sufflcient oxidation of the phosphorus in the phosphorinated oil, but should not be severe enough to oxidize more than minute quantities or the unphosphorized oil molecules. Formation of carboxyllc acids by ext-- dation of the oil hydrocarbons is to be avoided as far as possible.

Whensuitable oxidation of the original phosi phorized material has been accomplished in order to insure production of the desired phosphonic acids, the charge is then mingled with a suitable alkaline earth metal hydroxide, such as calcium hydroxide, in the presence of diluting quantities of water, and the batch heatednt a temperature around or; somewhat above the boiling point oi water fora time to effect saponification or con:

version of the phosphonic acids-into the calcium,

soap or salt, which material after filtering and washing is ready .for incorporation in an appro priate mineral lubricating oil such as a high viscosity index oil herein described, which oil may be of the same type as that which is phosphorized.

One specific method for the preparation of calcium phosphonates as herein described was as follows:

A parafllnic oil which was a highly solvent-refined lubricating oil of SAE 20 grade having 89 V. I., was heated to 300 F. and tour five per cent by weight (20% total) additions of yellow phosphorus were made while heating from 300 F. to

400 F. The oils were heated at all times in a to one hour. The respective oil was then cooled to 200 F. and a stream of air was passed through the oil at a rate slow enough to prevent temperature rise above 250 F. After air blowing caused no further evolution of heat, the oil was cooled, washed free of water-soluble acids, and the calcium soap was preparedby heating the resultin phosphonic acids with calcium hydroxide at 300 F. for one-half hour. The batch was filtered at 300 F. for removal of solids. This resulted in about 4% of soap in about 96% unmodified oil.

Another method which was employed is as dollows: Y

Nine quarts of said SAE 30 grade oil having a V. I. of 89, were chlorinated at l50-170 F. by

bubbling a rapid stream of chlorine through the oil. The process was continued until'2.0 of chlorine had been absorbed, as judged by the increase in weight or the charge. .The chlorinated oil was then heated and stirred with 2% of yellow phosphorus. Thetemperature was raised to 475 F. and held at that point for three hours.

(In another instance the temperature was raised to about 625 F. which insured removal from the product oi the trace of chlorine retained.

when a temperature of only 475 F. was used.)

The total charge was cooled to 200 F. and a rapid stream oi air passed through the oil until heat evolution ceased (approximately 15 minutes), the

.temperature being held in the meantime to a depercentages perhaps as low as 0.25% to 0.5% may be used and higher percentages up to 2% V. G. C. were changed by reason of an extract added as stated below.

one hour with 200 grams of calcium hydroxide and 300 ml. of water at 200 F. The water was evaporated off by final heating to 230 F. The charge was'cooled, 200 ml. of ethyl alcohol was added to'insure complete saponiflcation, and the "heating and stirring was continued for one hour until the temperature reached 300 F. The total charge was then filtered as above. The filtered oil tested as follows:

'Soap'nurnber 8.4 mg. KOH/g. oil Phosphorus; 0.25% Sulfate ash 1.36%

p number, calc. from ash 11.4 mg. KOH/g. oil Soap number, calc. from phosphorus 9.0

This signified about 10% soap in about 90% unmodified oil.

The various salts or soaps produced by methods herein given may be readily incorporated into suitable mineral lubricating oils by mere agitation with slight warming if required. Ordinarily about 1% to 1.5% of the salt will be employed in the oil. However, as conditions vary or perhaps 3% may be employed. Larger percentages are of doubtful practical value and merely increase the cost, but unless very large do not materially increase the viscosity of the product over that of the original mineral lubricating oil.

A lubricating base oil particularly desired for additionsof these soaps thereto is one of highly parafiinic type produced by modern dewaxing.

and heavy solvent-refining treatments to yield a viscosity index of from about 80 (or 75) to 100 or higher. 1

Oils which have been used in practicing this invention and products therefrom possessed the following specifications: 0 v W :2

Oil A Oil B (77.9 V. I. base oil) (90 V. I. base oil) Basle oil Basie oil pus pus BASL 011 about 1% Base 01] about 1% on soap soap Viscosity Index (V. I.)

Dean and Davis 77. 9 79.0 89. 4 88.9 Viscosity gravity constant (V. C-. C.) 0.818 0. 824 0.810 0.810 Gravity, A. P. I. at

F L 27. 5 26. 9 20. 4 29. 3 Viscosity Saybolt Univ.

sec. at-

l00 F 563. 2 549. 0 374. 4 359. 2 210 F 63.2 02.1 54.0 54.5 Flash point, COG. F. 465 445 445 430 6 Fire point, COO, F 520 525 510 505 0 Pour point, F 5 5 5 (l Sulfate ash 0.0 0.15 0.0 0 l6 Soap number. 0.0 1.0 u. 0 0. 09 Phosphorus 0.0 0.025 0.0 0.02 Chlorine 0. 0 Trace 0. 0 0. 0 Color,N.P. 8+ 4.5 8+ Acid No., 95% alcohol method 0.04 0.12 Carbon residue 0. 04 0. 22

I Norm -The presence 6r a lower viscosity, higher V. I. oil in the concentrate (about 10% soap) added to the base oils served to produce the differences in V. I., viscosity and flash point. Gravity and 7 themselves from mixed Western The above described mineral lubricating oils containing calcium phosphonates produced by the methods above described were tested on a Falex film strength testing machine with the results given in the following table, and the 90 V. I. oil with and without about 0.7% of the free phosphonic acids produced by the first method also was tested for film strength with the results appearing in the following table:

Results of Falea: tests Torque-in. lb.

90 V. I. oil 90 V. I. oil V. I. oil V I pluis 0.3% pllus 01.7% pins 1% ca cium p osp 0111C ca cium Jaw pnssums oil soap of acids soaps oi phosphouic made from phosphonic acids unchlorinacids made from ated oil made from unchlorin- (acid No. chlorinetad 011 1.0) ated oils 5 5 7 7 9 9 13 l2 l5 l4 l8 17 20 20 24 22 28 24 32 26 36 27 39 29 43 Failure 48 51 54 55 63 Failure The oil from 77.9 V. I. oil and containing about 1% of calcium salts (produced by the first method) was run in a Diesel engine for hours and gave exceptionally clean pistons and rings. Only a slight discoloration due to varnish deposits was found on the piston, and only slight deposits around and behind the rings were found. No ring quadrants were stuck and there was no bearing corrosion. This same oil was tested for corrosion on sensitive bearings of the copperlead type by oxidizing for about 100 hours and then subjecting the bearings to an augmented corrosion test with said oxidized oil. No corrosion was developed in 16 hours. This same oil containing 1.5% of the calcium soap produced even cleaner pistons. However, the base oil (without soap addition) stuck the rings at 39 hours in a similar engine run. The same base oil on the same kind of corrosion test with 1% of a calcium carboxylic acid soap showed heavy corrosion at the end of four hours.

The 90 V. I. oil containing about 1% soap when run in an ordinary internal combustion engine of the automobile type showed an exceptionally clean piston with unusually clean, free rings after a run of 100 hours.

All these oils contained as an oxidation inhibitor about 1% of a phenol extract fraction obtained in producing the original base oils (Santa Fe Springs, California) crude containing wax. The phenol extraction was accomplished by a known well-understood method. The extract was in turn re-extracted with phenol containing about 20% water to recover about 15% to 20% of the initial extract. This recovered re-extract possessed a lower A. P.I. gravity (i. e. heavier) than the whole extract. This extract fraction apparently also tends to act as a solubilizer for sludges and the like.

- Aci when these oils were subjected to an-oxidation test similar to the Indiana testhut modified to approximate motor conditions the oils havin about 1% or calcium soap of the present invention) they yielded theiollowing acid numbers:

Containing 1% extract No dation, mg. KOH/g .dation, mg. KOH/g.

be after-'- oxidation, mg. EOE/g sea see

sac

These results may be contrasted with the same oils containing equivalent amounts of "calcium p of carhozwlic acids which showed acid number of 0.92 mg. KOH/g. after 24 hours, 2.14 after '38 hours, and 5.52 after 96 hours.

Similar oils have been used wherein the same high viscosity index base lubricating oils were employed with the same amounts of calcium they do not cloud. There is no gelling tendency,-

and the soaps are sumciently soluble in the high viscosity index oil described that concentrates containing as high ass-% soap or even more may be prepared and shipped or stored. Another acl= vantage of these soaps and oils containing thesesoaps, is that they do not hydrolyze, and where moisture conditions are encountered in practical engine uses the presence of the moisture does not ailect the soap nor cause separation nor gelling nor emulsiflcation. Similarly, where the phos- 200? F. with refluxing for 8 to 10 hours or until evolution of HCl ceases. The mass is then by reacting the mineral oilfraction wlth 20% phosphorus trichloride and 20%" aluminum 1 chloride at a temperature slightly; der about hydrolyzed with hot water and the aluminum chloride washed free. Thebatch containing the excess oil is then air blown (as above) to conve'rt "the phosphorous compounds into phosphonic acids which may be converted into soaps as above described in connection with the other methods.

It is to be understood that the above disclosures are merely illustrative of the generic invention and are not to. be taken as limiting.

I claim:

l. A method for producing a mineral lubrieating oil for severe service internal combustion engines comprising heating a mineral oil toan incipient cracking temperature in the presence of phosphorus to cause phosphorus'to enter the hydrogen molecule and oxidizing the phosphorized oil under controlled temperature conditions to yield phosphonic acids in said oil.

2. A method according to claim 1, in which the mineral oil is heated to a temperature of approximately 600 F.

3. A method according to claim 1, in which the mineral oil has a high viscosity index;

4. A method according to claim 1, in which the mineral oil is a solvent refined highly paralfinic lubricating oil.

5. A process according to claim 1, in which the phosphorized oil is oxidized with air at a temperature of approximately 250 F.

6. A method according to claim 1, in. which the mineral oil is chlorinated prior to heating it p to an incipient cracking temperature.

phonic acids themselves are added to the oils as film-stir or oiliness agents, no objectionable resultsare encountered upon storage or standing or use in the presence of moisture and the like.

The phosphonic acids which have been produced by the above described methods have contained 16 or more carbon atoms per molecule. To

insure adequate oil-solubility or their soaps such acids should contain at least about 10 carbon atoms per molecule. In blending-the phospho nates with the oils, the soap additionhas geneasily been based onthe sulfate ash produced. It may vary from calcium sulfate ash of about 0.1%

to' about 0.6%. This will vary the soap content in the finished oil from about 0.25% to about3%, the lower the molecular weight of the acids (lower number of carbons per molecule) 'the greater will be the calcium content and the higher the calcium sulfate ash test. Ordinarily, in the order of about 0.75% to 115% of the soap will be adequate.

. In addition to-uslns calcium soaps it will be appropriate, at least for some uses to employ magnesium soaps 'or barium soaps, i. e. the alkaline earth metal soaps. However, I prefer for .practical- Diesel engine purposes the calcium soaps here described, and in general, I prefer to employ around 1% or 1.5% at soaps from those acidsproducedtr'oni lubricating oil fractlonsot the type indicated.

Acids suita e for the production of soaps ac- 'cording to t invention may also be prepared '7. A method according to claim 1, in which the mineral oil is first chlorinated and then heated to a temperature of approximately 475 F. in the presence of the phosphorus.

8. A method for producing a mineral lubrieating oil for severe service internal combustion engines comprising heating a mineral oil to an.

incipient' cracking temperature in the presence of a small amount of phosphorus to eflect chemical combination with hydrocarbon, oxidizing the phosphorized oil under controlled temperature conditions to yield phosphonic acids in said oil and reacting said, phosphonic acids insaid oil with an alkaline earth metal hydroxide to yield alkaline earth metal soaps of phosphonic acids, in. said oil. 1 r

0'. A method according to claim 8, in which the mineral oil is heated to a temperature of approximately 600 F.

' 10. A method according to claim 8, in which the mineral oil has a high viscosity index.

11. A method accordingto claim 8,1n'which the-.mlneral oil is a. solvent refined highly parafllnic lubricating oil. i

12. A process according to claim'g m wmch the phosphorized oil is oxidized with air at a temperature of approximately250 F.

13. A method according to claim 8, in which the mineral oil is chlorinated prior toheating it to an incipient cracking temperature.

14. 'A method accoiding to claim 8, in which the mineral oil is, first chlorinated and then.

heated to a temperature or! approximately 475 F. in the' presence of the phosphorus.

15. A method according to claim'8, in which i the alkaline earth metal hydroxide is calcium hydroxide.

16. A method according to claim 8, in which the alkaline earth metal hydroxide is magnesium hydroxide.

17. A method according to claim 8, in which the alkaline earth metal hydroxide is'barium hydroxide.

18. A method according to claim 8, in which the completed oil contains approximately to 19. A method according to claim 8, in which the mineral oil is a highly paraflinic type oil, and the finished oil comprises from to 3% of the produced soap in highly parafllnic type min eral lubricating oil.

HAROLD W. RITCHEY.

CERTIFICATE or CORRECTION. Patent No. 2, 11,505. February 16, 1915.

mom) w. RITGHEY.

It is hereby certified that errgr appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 514., for "SAE 50 grade" read -SAE 20 grade---; page 3, first column, line 65, in the table, for "5714.11." read "5 1 7 -b,- page 1p, second column, line 22, claim for "hydrogen" read --hydrocarbon-; 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 18th day of January, A. D. 191m.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.