US2204601A - Compounded lubricant - Google Patents

Description

I corrosivity, especially with respect to modern Patented June 18, 1940 UNITED STATES PATENT OFFICE COMPOUNDED LUBRICANT ware No Drawing. Application February 23, 1937, Serial No. 127,192

2'! Claims.

This. invention relates to new and useful compositions of the compounded mineral oil class. More particularly, it involves the provision of a lubricating oil containing metal salts of organic acids and an addition agent which inhibits undesirableeflects of such compounds, as more particularly pointed out hereinafter, without destroying desired beneficial eflects obtained therefrom.

Metal salts of organic acids are known as compounding ingredients for lubricating oils and have been added thereto for various purposes. For example, aluminum oleate is disclosed as a dispersing agent for graphite in the U. 8. Patent to Burke #1,732,221; and various-soaps have been disclosed as pour point depressing agents.

In its broader aspect this invention is applicable to compounded oils of the above types. However, the present invention is more particularly concerned with oils compounded with certain metal naphthenates such as aluminum or magnesium naphthenates to inhibit piston ring sticking.

An important property of lubricating oils is low bearing metals such as copper-lead mixtures or cadmium-silver alloy. Some lubricating oils which have been entirely satisfactory from the standpoint of corrosivity to high grade Babbitt bearing metals show a corrosion rate with cadmium-silver and copper-lead bearings which is greater than that permissible. Lubricating oils containing metal soap compounding ingredients have been found in general to show undesirable corrosive effects on such bearing materials. However, these-metal soap compounding ingredients are highly desirable or even necessary for other purposes,- such as inhibitors for piston ring sticking.

Accordingly, it is an object of the invention to solve the above difliculties by providing an improved compounded mineral oil having little or no corrosive action to machine parts and yet containing metal salts of organic acids.

Another object of the invention is to inhibit corrosive eflects oi compounded lubricating oils containing metal salts of organic acids such as metal naphthenates.

A still further object of the invention is to improve the wear reducing value of mineral oils compounded with metal salts such as naphthenates.

Another object of the invention is to increase the resistance to oxidation and discoloration of oils compounded with metal soaps.

In the investigation of lubricating oils containing metal salts of organic acids such as metal naphthenates, it has been found that oil-soluble organic compounds comprising an ester with a hydroxyl group in the alpha or beta position relative to the carboxyl group materially improve various properties of the compounded oils. These types of compounds may be represented generically by thefollowing structural formulae:

Alpha hydroxy ester Rr-CH-GOB,

Beta hydroxy ester Br-O-O-OKr-CH-h RPOECHQCO-BI In these formulae R1 and R2 represent an alkyl,

aryl, aralkyl or cyclic non-benzenoid group. R; and B: may, of course, contain other active groupings and may be either of the same or different types.

Attention is directed to the fact that in the above types of compounds the hydroxyl group is no more than two carbon atoms removed from the carboxyl group. The addition of these types of esters to oils containing metal soaps effectively inhibits the corrosive action of oils so compounded, but where the hydroxy] group is further removed than two carbon atoms from the carboxyl group it has been our experience that the esters do not adequately inhibit the corrosive action of such oils. The inferior inhibiting efiects obtained from these other types of hydroxy esters make it necessary to utilize an alpha or beta hydroxy ester in order to obtain the fullest benefits of this discovery and invention. 4

Specific examples of esters which have been found eflective for reducing corrosive efiects of eral lubricating oils containing metal naphthenates comprise diethyl tartrate, dibutyltartrate, diamyl tartrate, di-isoamyl tartrate, dibenzyl tartrate, dioctyl tartrate, dilauryl tartrate, amyl lactate, octyl lactate, tri-isoamyl citrate, and diethyl mucate.

aeoaeoi ether and carefully wiped with a soft cotton cloth.-

At the same intervals the oils were tested for viscosity, A. S. T. M. naphtha. insolubles; and neutralization number to obtain their oxidation characteristics. The duration of the testwas Z2 To illustrate the effect of these esters as corhours. Summarized results are given in Table rosion inhibitors, strip corrosion test data were #1.

TABLE #1 12 hours at 300 F.

Addition agents Weight loss in Type 01 oil grams Percent increase s {aha Neut. cam viscosity No. Metal nnphthenate Ester fg? miumat silver Western 011 (A) BAE 30- -None None. .0100 0 98 192 2.34 D0 1% likdl alinaphthenate (270 M. W. (10 .0870 1134 320 670 4.04

- 1% dibutyl tartrata- 025 0 0030 119 246 3. 60 a dlbutvl tartrate. 0258 l 0055 94 l odiocty tertreteu .0584 .0449 123 3.39 1% diamy termite .0176 .0064 1% diethyr tartrate .0124 0124 259 438 4. 21 1% dibenzyl tam-aw- 0230 0 33 3. 34 None .0475 .0001 293 3.06

Do- 1% dibutyl tam-ate 0040 0 123 187 2. 40 Pe gnsylvema motor 011 SAE None 1350 1620 72 2 2. 80 'Do 1% 1% ()iinaphthenate (210 M. w. -do .2087 .2315 11s 5 4.30

361 S D0 do r- 1%dibutyl tartraten .0372 .2330 93 1 3-80 Penn. aviation oil SAE 60... None None 0874 .0453 20 0 D0 1% $1inaphthenate (270 M. W. do 1495 1702 74 4 8.01 S 0 do 1% dibutyl tartrate 0299 2225 56 3 Wggtern motor oil (A) SAE None Non .0100 0 98 192 2. 34 b0 1% naphthenate (270 M. W. (lo .1391 1191 216 7 3- 0 am D0 do +1%dibutyltartrate .0366 .1331 279 393 3.33 D0 1% naphthenate (340 M. W. None .2083 .0640 440 710 1 801 D0 do +l% diamyltarttate .0122 .0003 329 447 5-8 W egtern motor on (B) SAE 1% L3; naphthenate 270 M. W. None .1353 .0629 112 183 4.9

aci D0 .l. do 1% diamyl tartrate" 0618 0056 139 3 9 3- 59 Blended Penn. and Western N n Nona .0523 o oil SAE 20.

D0 l\g naphthenate (270 M. W. de .1843 .0070 2 59 3.01 D do +1%dlamyl tartrate. .0275 .0007 35 36 4 obtained on several mineral oils compounded with 1% of-a metal naphthenate to which had been added difierent esters as taught in this invention. A basic aluminum naphthenate containing 3 equivalent weights of aluminum to 2 equivalent weights of petroleum naphthenic acids, and magnesium naphthenate were used as the metal naphthenate addition agents in these tests. Likewise, petroleum naphthenic acids having an'average molecular weight of 270, 340, and 370 were used in various of the different tests to illustrate the relative efiects of the molecular weight of the naphthenic acids on corrosiveness and other properties of the oil. v

The strip corrosion tests were carried out in the following manner: Glass tubes 2 inches in diameter and 20 inches long were immersed in an oil bath, the temperature of which was automatically controlled to within '1 F. of the test temperature which was 300 F. Approximately 300 c. c. of oil under the test was placed in each tube and air was bubbled through it at the rate of 10 liters per hour. Strips of the different types of bearing metals were cut to size and.

placed in the oils; in most cases more than one type of metal was tested simultaneously in the same sample of oil. The weight loss oi each strip The results in Table 1 include a large number of combinations of difierent types of oils, various metal naphthenates and different types of esters on two different bearing metals. It will be noted that some esters are more effective than others, and that the effectiveness of a single" ester 4 varies with the mineral oil used, the naphthenate contained therein and the bearing metal being tested. The data illustrate the following facts:

(1) Oils from Western crudes are essentially noncorrosive.

(2) The addition of metal naphthenates such as aluminum dinaphthenate or magnesium naphthenate increases the corrosiveness of mineral oils to copper-lead and cadmium-silver bearlng metals.

(3) The addition of hydroxy esters such as disclosed in this invention to oils containing these naphthenates markedly reduces their corrosiveness to these bearing metals.

It has also. been found that oils containing naphthenates from the heavier acids and from the lighter acids do not difier greatly in corrosivenessbut that the corrosive action of oils containing soaps of the heavy acids may be more effectively inhibited by the esters. The data in Table 2 are of interest in this'respect.

TABLE #2 Weight loss (grams) in 72 hours at 300 F.

Oil

' Copper- Cadmiumlead silver Western oii-SAE 30 .0100 0 Western oil-SAE 30+l% Al dinaph. (270 M. W. acid) .0670 .1134 Western Oil-SAE 30+l% Al dinaph.+l%

diamyl tartrate .0176 .0064 Western Oil-SAE 30+1% A] dinaph. (M0

M. W. ac .0475 0001 Western oil-SAE 30+i% Al dinaph.+l%

dibutyl tartrate 0040 0 Western oil-SAE 30+1% mag. naph. (270 M-W.aci .1391 .1191 Western oil-SAE 30-14% mag. naph.+l% w l? t flt'mie" ""'fi"i&6'

es rno mag. na M. w. acid .1 .2 .2083 .0640 Western oil-SAE 30+l% mag. naph.+i%

diamyl tartrate 0122 0003 Investigation also shows that addition of esters in accordance with this invention, to oils compounded with aluminum dinaphthenate very ma- It should be noted that wear consists oi corrosion and abrasion, and, strictly speaking. represents two difierent effects. Corrosion is the result of chemical attack of ingredients in the oil on the metal. This, of course, may occur on stationary parts and independently of abrasion. 0n the other hand, wear may result primarily from abrasion of the metal surface due to contact under load between moving parts. Similarly this phenomenon may occur in the absence of corrosion. Most generally both eflects occur simultaneously in a running engine and in order to more closely simulate such conditions a series of tests was run on a General Motors connecting rod machine, in which both factors, that is. high temj peratures causing accelerated corrosion and contact between moving surfaces. are present. The

results of these tests are tabulated below.

TABLE #4 Efiects of esters for inhibiting corrosivity and notes (General Motors connecting rod maabrdsion with oils containing metal naphthaterially reduces the amount of wear and friction. chine) as. re: se:

w oss gms. 64 hours at W 1. Mineral oil stock Soap compound Inhibitor (ester) Copper-lead g g as: 270 M. W. acid .3. 17 dihutyl tartmte... .4536 .2459 do 1 diamyl tartrate... .758) .7416 1% Al dinaph. (340 M.- W. acid).. 0.2% diamy} tartrate-. .0925 6237 17:c1 igagnesium naphthenate (340 M. W. 6.1912 ao 1% diamyltartrate.- 2.0m

Described Nat. Pet.- News, Nov. 11, 1936, Page 31.

Test results on 3 different types of laboratory machines are tabulated below:

Teens #3 Effects of esters an oiliness of oils containing aluminum dinaphthenate asse t;

hours at 2 be. steel on bmgm' load rmmkan 5it./min.l76 F.

machine,"

steel on bronme, Wear-Mg block Relative temp., "F

Ball Cup Frlct. Wear Test oil No. 1 Test oil N0. 1% Al dinaph. (270 M. W. acids) Test oil No. 1 1% Al dinaph. 1% diamyl tartrata. Test oil No. 2 Test oil No. 2 1'7 A1 dinaph. (270 M. W. acids) Test oil No. 2 1% Al dinaph. 1% dibutyl tattrate.. Test oil No. 3 Test oil No. 3 1'7 A1 dinaph. (270 M. W. acids) Test oi] No. 3 1 0 Al dinaph. 56% diamyl tartrate.

A laboratory wear testing machine comprising a 56-inch steel ball against a 34-inch steel cylinder which is rotated at 600 R. P. M. and which dipsin the 611 being tested. I

"Described in S. A. E. Journal, volume 28. page 63, 1932.

'Describcd in A. P. 1. Proceedings, mid-year 1032, section III, page 00 (published by Petroleum Team #5- Mineral oil stock Soap compound r as ymou a a laboratory tests, oil temp.: 108 and 279 F. a

Loss in weight per bearing for last 1,050 miles of a 2,925 mile run inhibitor (ester) Cadmiumsilver, grams Copperlead, 8

Blended lienn. and Western oil SAE 30.

1% $1 dinaph. (270 M. W. acid). o

. do 1% Al dinaph. (340 M. W. acid).

1% diamyl tartrate o 0.5% diamyl tartrate.

The tests in the 1935 Plymouth engine were made with the engine directly connected to an electric dynamometer, and the engine was run alternately hot and cold at the temperatures indicated in the table. In the cold part of the cycle the speed was 1500 R. P. M. (30 miles per hour), the load was 5.9 horsepower, and four ounces of distilled water were added at the start of the period to simulate conditions produced by densation of moisture in the crankcase. m

con-

were loaded with fan dynamometers. The jacket temperature was maintained at 345 F. by the use of ethylene glycol in the water jackets and the crankcase oil temperature was maintained at 220 F. with an electric heater. The results in Table No. illustrate clearly the beneficial cheat in preventing piston ring sticking which these oils give as compared with the same original uncompounded crankcase lubricant.

TABLE #0 Efiectiveness of oils containing aluminum dincphthenate and esters, in inhibiting piston ring sticking Lauson engine, jackgtFtemg Oil N aphthenate Ester g g 562 hours to cause ring sticking Western SAE 80. N n None 30 D 17 Al dinaph. (270 M. W. acids 1% diamyl tartrate. 90+ Do 1 Al dmeph. (340 M. w. acids do 60 Do 1% Mg. naph. (270 M. W. acids 00+ Do 1% Mg. mph. (340 M. W. acids do 10 (Plus sign indicates ring sticking had not yet occurred.)

the hot period the speed was'2500 R. P. M. (50 miles per hour), and the load was 25 horsepower. Both copper-lead and cadmium-silver hearings were provided in the engine to obtain accurate comparative data. Only the weight losses of hearing metals during the last two thirds of the run were considered, since the initial wear rate is entirely out of line with that of the greater portion of the run. The data thus obtained are more representative oi long operatiing periods.

The results of thQEaGDfiiD-Q tests show that tartrates are very efi'ective in inhibiting wear of hearings with oils containing aluminum aphthenate. 7

To ascertain the efiectiveness of oils containing both naphthenates and esters for inhibiting piston ring sticking, tests were run in Lauson engines todetermine the time necessary to cause piston ring sticking under highly adverse condiinvention prevented ring sticking for two, three or more times as long.

The chemical mechanisms by which the results of this invention are obtained have not been established and are not well understood. Metal naphthenates appear to catalyze corrosion effects in oils. The esters inhibit or offset this catalytic action by a phenomenon which has been discovered by the present inventors but which they are unable, definitely, to explain. The phenomenon of corrosion inhibiting appears to result from some peculiar action which converts the bearing metal to a passive state after an initial induc tion period. This latter fact is illustrated by the following comparative data:

tions. These engines are of the gasoline type and Strip corrosion-total weight loss grams copper-lead at 300 Test No. Oil Naphthenate Ester 24 hours 48 hours 72 hours 1%Al dinaph.. .0189 .0359 .0573 o .0085 .0198 .0307 3 0158 0170 0158 0136 .0181 .0151 5'" 0138 .0758 1092 Strips dipped in straight dibutyl tartrate before start of test.

Oil changed very 24 hours. "Specimens every 24 hours.

Examination of the above data shows that dipping the specimen in dibutyl tartrate markedly reduced .corrosion; that changing the oil every is hours had no effect on the corrosiveness of the oil containing both the naphthenate and the ester; and that when the bearing strip specimens were changed every 24 hours, the ester showed substantially ,no corrosion inhibiting action.

These facts indicatethat the'metal surface mustsidered when compounding oils according to this invention is the presence of free acid in the esters. Tests with tartrates indicate that best results are obtained when the free acid content of the ester is low. It is therefore preferred to use esters having a neutralization number of no more than approximately 20. r

Measurable improvements in the properties of the compounded oil are obtained with as little 0.1% of the ester, but approximately 0.5%, and preferably. as much as 1.0%, is required to obtain adequate reduction of corrosivity in the compounded oil for the purpose of this invention. More 'than 10% is regarded asunnecessary.

The present invention is applicable in its broader aspects to oils compounded with many oil soluble metal salts of organic acids. The invention appears at present to find its greatest utility in oils containing metal salts of organic carboxylic acids, and particularly in oilsv containing metal naphthenates capable of inhibiting piston ring sticking. Such metal naphthenates are aluminum, zinc, magnesium, cobalt, cadmium and manganese naphthenates. It is apparent that the particular ester and the particular metal salts must be selected with various factors in mind,

such as the service to be encountered and the type of bearings in engines to be lubricated if the maximum benefits of the invention are to be obtained. 4

While the character of the invention has been given in detail and numerous illustrative examinvention which is of the scope of the claims appended hereto.

We claim:

1. A compounded mineral oil containing an addition agent in an amount normally-sumcient to substantially increase the corrosivity of a mineral 011, said addition agent being a metalsalt'of an organic acid and selected'from the group of compounds which increase the corrosivity of hydrocarbon oils tohearing metals such as copperlead mixturesand cadmium-silver alloys, and a small amount of an organic hydroxy e'ster having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of said ester whereby the corrosivity f the mpounded oil is materially reduced.

2. A compounded mineral oil as defined in claim 1, in-which the ester is an alpha hydrcay ester of. the type formula in which R1 and R2 represent an alkyl, aryl, aralky'l or cyclic non-benzenoid group.

3. A compounded mineral oil as defined in claim 1, in which the ester is a beta hydroxy ester of the type formula in which R1 and R2 represent an alkyl, aryl, aralkyl or cyclic non-benzenoid group,

4. A compounded mineral oil as defined in claim 1, in which the ester is a beta hydroxy ester of the type formula in which R1 and R2 represent an alkyl, and, oralkyl or cyclic non-benzenoid group.

5. A compounded lubricating oil containing an oil-soluble metal salt of an organic carboxylic acid in an amount normally suflicient to 51 metals-,- tially increase the corrosivity of said oil to hearing metals such as copper-lead mixtures and cadmium-silver alloys, and an organic hydroxy ester having at least one hydroxyl group no more than two carbon atoms from a carboxyl group of said ester, said hydroxy ester. being present in an amount sumcient to materially inhibit the corrosivity of the'compounded oil.

'6; A compounded lubricating oil as defined inclaim 5, in which the ester is an alpha hydroxy ester of the type formula ar-on o-ro -an in which R1 and R2 represent an alkyl, aryl, aralin which R1 and R2 represent an alkyl, oralkyl or cyclic non-benzenoid group.

8. A compounded lubricating oil as defined in claim 5, in which the ester is a beta hydroxy ester of the type formula al-cn-om-c-o-u,

in which R1 and R2 represent an alkyl, aryl, aralkyl or cyclic non-benzenoid group 9. A compounded lubricating oil containing a small amount of a naphthenate selected from the group consisting of aluminum, zinc, magnesium, cobalt, cadmium and manganese naphthenate, said naphthenate being present in an amount suiilcient to substantially increase the corrosivity of the oil to. bearing metals such as copper-lead mixtures and cadmium-silver alloys, and from approximately 0.1% to approximately 10% of an organic hydroxy ester having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of said est-er.

10. A compounded lubricating oil as defined in v claim 9, in which the ester is an alpha hydroxy ester of the type formula m-cm-g-o-m in which R1 and R2 represent an alkyl, aryl, aralkyl or cyclic non-benzenoid group.

11. A compounded lubricating oil as defined in claim 9, in which the ester is a beta hydroxy ester of the type .formula m-o-o-cm-oH-m in which R1 and R2 represent an alkyl, aryl, aral-- kyl or cyclic non-benzenoid group.

12. A compounded lubricating oil as defined in claim 9, in which the ester is a beta hydroxy ester of the type formula .Rr-CH-CHa-C-O-Ra 'in which R1 and R2 represent an alkyl, aryl, aralkyl or cyclic non-benzenoid group.

13. A compounded lubricating oil as defined in claim 9, in which the ester is a tartrate.

14. A compounded lubricating oil as defined in claim 9, in which the ester is a tartrate, and the naphthenate is an aluminum naphthenate.

15. A compounded lubricating oil as defined in claim 9, in which the ester is a tartrate, and the naphthenate is magnesium naphthenate.

16. A compounded .mineral oil containing an aluminum salt of a fatty acid inan amount suificient to normally increase the corrosivity of said oil and an organic hydroxy ester, having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of .said

increased corrosivity.

ester, said ester being present in an amount sufficient to materially inhibit said increased corrosivity.

17. A compounded lubricatirig oil containing a metal salt of an organic carboxylic acid in an amount sufliciently to normally increase the corrosivity of said oil and an oil soluble tartrate, in an amount sufiiciently to materially inhibit said 18. In a method of lubricating bearing surfaces which comprises maintaining between the hearing surfaces, one of which is a bearing metal selected from the group consisting of cadmiumsilver alloy and copper-lead mixtures, a film of a compounded lubricating oil containing a small amount of a metal naphthenate which oil would normally tend to corrode said bearing metal, the

step of inhibiting the corrosive action of the cornpounded oil on said bearing by incorporating therein a minor proportion of an organic ester,

having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of said ester, said minor proportion ofester comprising at least 0.1% by weight of the lubricating oil.

19, In a method of lubricating bearing surfaces which comprises maintaining between the bearing surfaces, one of which isa bearing metal selected from the group consisting of cadmium-silver alloy and copper-lead mixtures, a film of a compounded lubricating oil containing a small amount of a metal naphthenate selected from the group c911".

sisting of aluminum, zinc, magnesium, cobalt, cadmium and manganese 'naphthenates which compounded oil would normally tend to corrode said bearing metal, the step of inhibiting the cor rosive'action of the oil on said bearing by incorporating therein aminor proportion of an organic ester having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of said ester, said minor proportion of ester comprising at least 0.1% by weight of the lubricating all.

A compounded mineral oil as defined in claim 1, in which the proportion ofhydroxy ester is from approximately 0.1% to approximately 10% by weight based on the mineral oil.

A compounded lubricating oil 'as defined in claim 5, in which the proportion of'hydroxy ester is from approximately 0.1% to approximately 10% by weight based on the mineral oil.

22. In a method of lubricating bearing surfaces which comprises maintaining between the hearing suriaces, one of which is a-bearing metal selected from the group consisting of cadmiumsilver alloys and copper-lead mixtures, a film of a compounded lubricating oil normally tending to corrode said bearing metal and containing an addition agent-selected from the group of metal salts of an organic acid which substantially increase the corrosivity of said oil to said bearings,

the step of inhibiting the corrosive action of the compounded oil on said bearing by incorporating therein a minor proportion of an organic ester having at least one hydroxyl group no more than I two carbon atoms removed from a carboxyl group p of said ester, said minor proportion of ester comprising at least 0.1% by weight of the lubricating oil.

23. A compounded lubricating oil containing a small amount ofa metal naphthenate suflicient to substantially increase the corrosivity of the oil te bearing metals such as copper-lead mixtures or cadmium-silver alloys, and from approximately 0.1% to 10% of an organic hydroxv ester having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of said ester.

24. A compounded lubricant comprising a mineral lubricating 011 containing a small proportion of a metal salt of an organic acid in an amount sufficient to substantially increase the corrosivity of the lubricating oil to bearing metals, and from approximately 0.1% to 10% of an organic hydreary ester having at least onehydroxyl group no more than two carbon atoms removed from" a carboml group of said ester.

25. A compounded liquid-lubricant comprising a mineral oil containing a metal salt of an organic acid in an amount sufllcient substantially to increase the corrosivity of the lubricant to bearin metals, such as copper-lead mixtures and cadmium silver alloys, and approximately 1% of an ester having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl grow. of said ester.

compounded liquid lubricant comprising a mineral oil containing an oil-soluble metal salt oi an organic carboxylic acid in an amount suflicient substantially to increasethe corrosivity of loys and copper-lead mixtures, a film 01 a compounded lubricating oil containing'an bil-soluble metal salt of an organic carboxylic acid in an amount which would normally increase the corrosivity of said oil to said bearing metal, the step of inhibiting the corrosive action of the oil on said bearing by incorporating therein from approximately 0.1% to approximately 10% of an ester having at least one hydroxyl group no more than two carbon atoms removed from a carboxyl group of said ester.

FRANK W. KAVANAGH. VICTOR N. BORSOFF. ROBERT L. HUMPHREY S.