US2250188A - Lubricating oil - Google Patents

Description

Patented July 22, 1941 LUBRICATING 01L Cheater E. Wilson, San Pedro, Calif., asslgnor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application January 15, 1940, Serial No. 313,926

22 Claims.

This invention relates to mineral lubricating oils which have been modified by the addition of constituents to impart to them special characteristics especially adapting them to severe service uses such as are encountered in Diesel engines, high out-put aviation engines and the like, and also for controlling the development of corrosive conditions in various types of lubricating oils including highly paramnic oils.

In Diesel and similar engines the high temperatures developed in the cylinders tend to act upon lubricating oils to cause the deposition of resinous and varnish-like products on the pistons and elsewhere to produce lacquer-lik coatings and carbonaceous materials which tend to cause ring and valve sticking and interfere with engine operation. Further, fuel residues from incomplete combustion of fuel contribute to the deposition'of lacquer-like and carbonaceous materials in the engine. Previously in an effort to overcome these difliculties various types of metal soaps of fatty acids and the like have been introduced into the lubricating oil, and they have exhibited a detergent effect in that they have acted to prevent such depositions. However, in general, it has been observed that in those engines fitted with certain types of bearings which are highly corrosion-sensitive, such as cadmiumsilver or copper-lead bearings, the use of such fatty acid soap-compounded oils has often given rise to bearing corrosion, such corrosion apparently being due to the formation in the oil of corrosive materials of acidic character. The formation of these corrosive materials may evenbe catalyzed by the presence of such soaps in the'oil. Also, some of these metal soaps added as detergents have required the use of free fatty acid and the like to act as a common solvent to promote solution of the soaps in the oil, and the presence of such free acidity has possibly contributed to the corrosion of alloy bearings of the type mentioned above.

Primarily, the objects of this invention are to produce oils resistant to development of corrosive conditions in any type of engine, and also to produce for severe service conditions such as are encountered in Diesel engines, lubricating oils which will be non-corrosive to corrosionsensitive bearings of the copper-lead and cadmium-silver type and which will also avoid the deposition of lacquer and varnish-like materials upon pistons and overcome carbon deposition behind the rings in such en ines.

I have found that these objects can be obtained by dissolving in mineral lubricating oils a small quantity in the order of about to 1% of the calcium or other oil-soluble salt of the condensation product of formaldehyde with an alkyl phenol in which the alkyl group contains preferably 4 or 5 carbon atoms or more in the chain to insure oil-solubility without a common solvent but the alkyl chain shouldv not be so long as to yield heavy, oil-insoluble materials. This resinous condensation product is a weakly acidic noncarboxylic organic material due to its phenolic character, and has an ionization constant less than about 1 10 or approximately 1x10 It is a viscous liquid polymer with free hydroxyl groups indicative of the phenolic type and is readily reacted with hydrated lime to form the calcium salt or soap required for the present invention. When a larger proportion, for example in the order of 1.5% to 2% or 3% of this oilsoluble calcium salt is dissolved in the mineral oil it not only imparts non-corrosive characteristics to oil but may also impart some desired detergent property.

The invention therefore resides in mineral lubricating oils containing small proportions in the order of about 0.5% or 0.75% up to 2% or even 3% of oil-soluble metal salts, especially calcium salts, of the condensation product of formaldehyde with alkyl phenols where the alkyl contains a sufficient number of carbons to render the material oilsoluble but not an excessive number of carbons. The calcium salt of the condensation product of formaldehyde with amyl phenol is a desirableexample.

These materials when present in lubricating oils in the proportions indicated serve to prevent corrosion of th highly corrosion-sensitive alloy bearings of the copper-lead and cadmium-silver type. It is presumed that this inhibiting power is at least in part connected with the ability of the salts to react with corrosive acids formed in the lubricating oil by oxidation during use, whereby non-corrosive metal salts, for example, calcium salts of the corrosive acids are formed and the weakly acidic non-corrosive phenolic compounds'are released. Thus, these salts impart to the oil what may be termed reserve alkalinity because of this neutralizing ability. It may be true, however, that the metal salts of said condensation products act a anti-oxidants tendmg to prevent the formation of corrosive acidity.

- These materials appear to be soluble always in They apparently are also soluble in solutions containing acidic materialswith which they do not s,aso,iss-

- of detergent soapsin highly paraillnic oils, where solubility of the soaps in such oils is not adequate.

" Examples of such common solvents are diethyis desired to use other forms of "detergent soaps,

they may be employed in the indicated proportions, particularly around 0.5% to 1%, with other oil-sol -1 having said detergent properties such as between about 0.5% and 1% to 1.5% of oil-soluble soaps of saponiflable fatty acids or modified fatty acids.

By the term oil-soluble" is meant either the ability to enter into substantially true solution or to be so thoroughly dispersed as to avoid substantial clouding or separation of the soap or salt.

Therefore, the invention also includes the use of the indicated soaps of said phenolic condensation products in lubricating ofl in the indicated proportions, in combination with small amounts of other types of oil-soluble soaps having detergent properties in the engine in proportion sufllcient to overcome or greatly retard the deposition of resinous and varnish-like materials upon pistons, rings, valves and the like. Such soaps may be used in amounts in the order of 0.5% to 1.0% as required to accomplish the result desired. Such soaps are produced from soap-forming fatty acids and modified fatty acids such as the calcium and magnesium soaps of phenyl stearic acid and chlorostearic acids, and from naphthenic acids, rosin. acids, modified rosin acids, and synthetic petroleum acids formed by the oxidation of petroleum fractions such as highly solvent-treated paraflinic type lubricating oil fractions, paraffin waxes, petrolatum and the like. Other metals may be used for soap productlon,. as here indicated, where sufnciently oilsoluble soaps are produced.

Both with respect to the soaps of phenolic condensation products or resins and with respect to other indicated types of soaps used because of their detergent properties. the calcium soaps are in general preferred as the most practical, although soaps of the other alkaline earth metals,

lene glycol mono oleate, octyl acetate, diethylene glycol mono laurate, and diethylene glycol mono butyl ether.

The mineral lubricating oil to be employed may "be either a naphthenic type oil or a paraillnic type oil insofar as the salt of the phenolic condensation product or resin is concerned, because these materials are highly soluble in both types of oil,v However, where these phenolic soaps or salts are to be employed in conjunction with a detergent soap, it may then be desirable to employ a naphthenic type oil in the event that said detergent soap is not soluble suillciently in the paraillnic type oil. Where a naphthenic oil is employed it. may be a California or other oilof this type which may characteristically contain about 0.5% of organically combined sulfur naturally occurring therein or may contain as little as about 0.15% up to 4% or 5%, for example, 2.75% sulfur as in Santa Maria Valley (California) lubricating oils. The paraflinic type ofl may be either a typical paraflln base oil such as a Pennsylvania oil,'or a heavily solvent refined oil g highly parafllnic characteristics.

When adding the phenolic condensation product of the present invention it is desirable to employ enough to give the desired effect, for example, 0.75%, but the upper limit, for example approaching 3%, should be restricted so that it does not cause undesirable thickening of the oil either alone or in conjunction with the detergent" soap if added. Otherwise, it may be necessary to employ a neutral common solvent as above indicated.

barium and magnesium as well as strontium are inaddition I may, however, employ the oil soluble soaps of sodium, potassium, lithium, copper, zinc, aluminum, lead, iron, nickel, cobalt, manganese, chromium, tin, and in general all the metals and heavy metals. In addition to the alkaline earth metal salts mentioned above as a preferred group, aluminum and zinc may also generally be included because of high solubility of their salts or soaps in mineral oil and their possibly lower catalytic activity when employed in the detergent soaps.

In addition to the employment of these soaps the invention also includes the use of other oiliness or fllm strength agents therewith. For example, either type of soap may contain also chlorine or other halogen or sulfur or phosphorus, or the phenyl group in the detergent soap, and if required a neutral common solvent may be employed to increase the solubility of the metal salt in the oil. The latter requirement may be important where employing certain types In practicing the invention, a suitable condensation product of an alkyl phenol (e. g. amyl phenol) with formaldehyde may be manufactured and appropriate oil-soluble soaps, such as calcium soaps produced therefrom. For example, I have manufactured the condensation product of p-tertiary amyl phenol with formaldehyde employing both an acid catalyst and a basic catalyst. Where employing an acid catalyst I have used about 82 grams (0.5 mol.) of amyl phenol with from about 27 grams to about 49 grams (0.33 to 0.5 mol.) of 37% formalin (formaldehyde) with 2 ml. of 37 of hydrochloric acid. These materials were combined and refluxed for one hour where the higher molecular proportions of formaldehyde were used and up to three hours where the lower proportions of formaldehyde were used. The refluxing temperatures were conveniently carried between about 200 F. and 212 F., any appropriate range obvious to the skilled chemist'being suitable. when the condensation product was formed by refluxing as above, 'a liquid, resinous material was obtained when the smaller proportions of the formaldehyde were used and a more pasty material when the higher proportions of formaldehyde "were used. In each case the resultant liquid or paste as one part was then added to nine parts of a Galifornia or naphthenic base mineral lubricating oil containing characteristically about 0.5% of organically combined sulfur, said oil having a viscosity of 600 seconds Saybolt Universal at F. and an N. P. A. color of about 2. To

this mass there was added the water layer from the refluxing operation, this water being that of the formaldehyde solution. To this mass there was then added 37 grams (0.5 mol.) of hydrated lime and the batch was agitated for two hours at temperatures ranging between 180 'F and 200 F., and then cooled. In some instances 60 ml. of ethyl alcohol was then added and the batch further agitated for about two hours at 180 F. Where alcohol is used there is less hydrolysis and the calcium content is increased. In each instance the temperature and time of treatment and the nature of the treatment was such as to efl'ect conversion of the phenolic resin into the calcium soap thereof. In order to completely remove any unconverted lime and other solvents there was mixed into the batch a quantity of suitable filter aid such as ground diatomaceous earth (e. g. "Super-Gel) approximating the amount of the hydrated lime employed (about 37 grams), and the batch heated to 300 F. and filtered at about that temperature.

Suitable resins were produced in the same manner by employing 2 ml. of ammonium hydroxid'e containing 28% NH: as the catalyst instead of hydrochloric acid, the refluxing in these particular cases being slightly longer, the results apparently being equally satisfactory.

These products constituted concentrates, that is 10% of the calcium soap of the phenolic condensation product with 90% of the naphthenic mineral lubricating oil mentioned. These concentrates were dilutable in all degrees with either naphthenic base oils or paraffinic-type lubrlcating oils without precipitation of the soap after long standing. A higher soap concentrate can be obtained by using smaller amounts of oil, although the larger amounts render the mass more workable.

The same soaps have also been prepared directly by adding the hydrated lime to the original mass, thereby employing the lime as a catalyst. Thus 82 grams of amyl phenol, 328 grams of the mentioned 600 viscosity mineral oil and 37 grams of hydrated lime were charged into a closed flask, having a sealed agitator and a reflux condenser, and heated to 150 F. at which temperature the amyl phenol was melted. To this heated batch about 30 grams of 37% formaldehyde was introduced through the reflux condenser. Here the batch was refluxed at between 200 F. and 212 F. for about six hours. The product was then transferred to open vessel and agitated with 60 ml. of ethyl alcohol at 180 F..

for 2 hours and filtered at 300 F. with the filter aid known on the market as Super-Gel which is aground diatomaceous earth.

By this last described procedure formation of the phenolic condensation product with the formaldehyde and its conversion into the calcium soap thereof was effected directly in one operation to yield a concentrate containing soap.

These procedures indicate different methods of production of the soap of the condensation product required for the present invention. The condensation product usually is a thick liquid or pasty mass at normal temperatures. The amount of formaldehyde used in the preparation of the condensation product does not appear to be critical, but the proportion should be limited so that there will not be sumcient formaldehyde to result in the formation of polymers of excessive molecular weight which might as a consequence be not sufficiently soluble or dimcultly soluble in the lubricating oil desired to be employed. Other suitable soaps have been prepared by buying on the open market an amyl phenol-formaldehyde condensation product and saponifying the same with hydrated lime as above described.

Other alkyl phenols than amyl phenols where the alkyl group contains at least 4 carbon atoms such as butyl, hexyl, octyl, nonyl, decyl and others of 11 and more carbon atoms per group purposes inasmuch as the paraflinic type oil could be used because the resultant soaps are adequately soluble therein. However, the use of a naphthenic base lubricating oil is often indicated where other soaps of the detergent soap class, as above described, are employed for some uses in connection with the soaps of phenolic condensation product here disclosed.

For the production of lubricating oils for heavy service internal combustion engines such as Diesel engines, it is generally desirable to employ the second type or detergent-type of soap mentioned for the purpose of completely overcoming any ob- .lectionable tendency to deposit resinous or varnish-like materials upon the engine pistons and about the rings and in the ring grooves. As has been indicated above, between about 0.5% and 1.5% to 2% of the calcium or other preferred metal soap as herein designated of suitable saponifiable organic acids have been satisfactorily employed with between about 0.5% and 1.5% to 2% of corresponding metal soaps of the phenolic condensation producthereof. As a specific example, about 0.75% of various calcium soaps of the amyl phenol-formaldehyde condensation product above described has been employed with about 0.7% of the calcium soaps'of the synthetic petroleum acids produced by the oxidation of highly parafllnic lubricating oils, such as S. A. E. 20 and S. A. E. 30 grades of highly solvent-treated mineral lubricating oil fractions having viscosity indexes in the order of and. viscosity gravity constants in the order of 0.81 and less. The calcium soaps of the synthetic acids are readily made by oxidizing the oil by known processes and obtaining the calcium soaps of the acidic materials by known processes such as by saponii'ying the oxidation batch with sodium hydroxide and cracking out the desired oil-soluble acids with sulfuric acid, separating the oil-soluble acids as in an oil layer and then saponifying such separated acids in the presence of the oil with hydrated lime to form the calcium soaps thereof in solution in the oil, and filtering. Or the sodium soaps resulting from the saponification with sodium hydroxide may be treated with calcium chloride solution to effect conversion into the calcium soaps, and the oil-soluble calcium soaps recovered in solution in the oil layer present either by reason of unoxidized oil carried over in the batch or by the addition of lubricating oil to the batch.

Oils so manufactured and containing about 0.75% of each of the two types of soaps mentioned have been run in Diesel test engines equipped with copper-lead and cadmium-silver bearings and proved satisfactory after hours of test which is far in excess of normal Diesel engine use of a lubricating oil. Thus, itappears that oxidation acids formed in the engine from lubricating oil due to the presence of the detergent type of soap by catalytic effect or otherwise, have been either neutralized or inhibited by the action of or the presence of the soap of the amyl phenol-formaldehyde condensation product. If neutralization occurs. the original phenolic resin probably is released and the calcium combines to neutralize the oxidation acids. This results in the maintenance of a non-corrorive oil due to the fact that the phenolic material is so weakly acidic as to have no corrosive eflect on the bearings.

Where the soap of the phenolic condensation product or" resin is to be used solely to inhibit corrosive materials which may form in the lubrieating oils where other additive agents are not present, such soaps may be used alone, and when so used may be employed either in naphthenic oils or highly paraiilnic-type oils as previously stated. Also, in making the phenolic materials, the alkyl group of the alkyl phenol could have an aryl group attached thereto such as a phenyl group. Thus an aryl-alkyl phenol could be used in manufacturing the condensation product. Again, where the condensation product or resin will in itself act as an anti-oxidant or inhibitor in the oil, such material may be added to the oil without conversion into its salt or soap and in similar proportions to those where the salt or soap is used; and also sometimes in much smaller proportions, e. g. 0.1%; and the invention also extends to such modification.

In making soaps of the previously described oxidation acids for use with soaps of the phenolic condensation products hereof, either the mixed oxidation acids may be used for such soap production, or they may be fractionated in any suitable manner to yield any suitable acid fraction for employment in the soap production, for example the weaker acids which possibly would have less corrosive action in the engine should they become liberated from their soaps during use.

These disclosures are intended as illustrative of the generic invention and not as necessarily limiting thereof except as required by the prior art.

I claim:

1. A mineral lubricating oil containing a small proportion of an oil-soluble metal soap of the condensation product of formaldehyde with an alkyl phenol, in proportion to control the development of acidic conditions during use of the lubricating oil.

2. A mineral lubricating oil containing between about 0.5% and about 3% of oil-soluble metal soaps of oil-soluble condensation products from the condensation of an alkyl phenol with formaldehyde. r

3. A mineral lubricating oil containing between about 0.5% and about 3% of the alkaline earth metal soap' of condensation products of formaldehyde with alkyl phenols where the alkyl groups contain suflicient carbon atoms to insure good solubility of the soap in the lubricating oil;

4. A lubricating oil according to claim 3 wherein the soap is a calcium soap.

5. A mineral lubricating oil for severe service internal combustion engines containing a small proportion of an oil-soluble detergent metal soap of saponiflable organic acids in quantity to control the deposition of resinous and varnish-like lubricating oil.

materials in such engines, and a small proportion of an oil-soluble metal soap of condensation products of alkyl phenols with formaldehyde in quantity suiiicient to control the development of corrosive conditions toward highlycorrosive-sensitive bearings used in severe service internal combustion engines, wherein the quantity or soaps employed is insuiilcient to increase materially the original viscosityof the lubricating oil.

wherein the two soaps are employed in' proportions between about 0.5% and 3% of the total composition.

7. A mineral lubricating oil according to claim 5 wherein the lubricating oil is a naphthenic-type oil.

. 8. A mineral lubricating 011 according to'claim 5 wherein the base oil is a naphthenic-type oil and wherein each of thesoaps ispresent in amounts in the order of 0.5% to 1% 01' the total composition.

9. An 011 according to claim 5 wherein the soaps are calcium soaps.

10. An oil according'to claim 2 wherein the alkyl group is amyl.

1 1. An oil according to claim 2 wherein the alkyl group is amyl and the metal is calcium.

12. A mineral lubricating oil containing a small proportion of an oil-soluble compound of the condensation of formaldehyde with an alkyl phenol.

13. A mineral lubricating 011 containing a small proportion in the order of 1% of an oil-soluble corrosion-controlling metal salt producible by the\ reaction of a metal hydroxide, an alkyl phenol and formaldehyde.

14. A mineral lubricating 011 according to claim 5 wherein the detergent soap is a soap of the synthetic acids produced from the oxidation of highly paraflinic mineral lubricating oil.

15. A mineral lubricating oil according to claim 5 wherein the detergent soap is produced from synthetic acids obtained by the oxidation of highly parafiinic, heavily sulfur treated mineral lubricating oil fractions.

16. A mineral lubricating oil according to claim 5 wherein the soaps are alkaline earth metal soaps.

17. A mineral lubricating oil according to claim 5 wherein the lubricating oil is a paraiiinic type 18. A mineral lubricating oil according to claim 1 wherein the soap is an alkaline earth metal soap.

19. A mineral lubricating oil according to claim l3ltwherein the salt is an alkaline earth metal sa 20. A mineral lubricating oil according to claim 1 wherein the soap is a barium soap.

- 21. A mineral lubricating oil accordingto claim 1 wherein the soap is an alkali metal soap.

22. A lubricating oil according to claim 5 wherein the soap is an alkali metal soap.

CHESTER E. WILSON.

6. A lubricating oil according to claim 5.