US 3214377 A
Description (OCR text may contain errors)
Oct. 26, 1965 5. w. HOTTEN 3,214,377
PHENYLAMIDES OF ORGANOAMINE POLYACETIC ACIDS AS ANTI-XIDANTS IN GREASES Fil'ed Aug. 5, 1962 2% AMIDE BASE GREASE AMIDE 1% AMIDE\- OXYGEN PRESSURE, PSI
o I I I TIME AT 250F, HOURS INVENTOR BRUCE W. H07'7'EN BY l.- n v.1 a,
United States Patent PHENYLAMIDES 0F dRGANOAMINE POLY- ACETIC. ACIDS AS ANTI-OXIDANTS IN GREASES Bruce W. Hotten, Orinda, Califl, assignor to California Research Corporation, San Francisco, Calif., 21 corporation of Delaware Filed Aug. 3, 1962, Ser. No. 216,015 11 Claims. (Cl. 252-33.6)
This application is a continuation-in-part of patent application Serial No. 58,244, filed September 26, 1960, now abandoned, and patent application Serial No. 90,649, filed February 21, 1961, now abandoned.
The present invention pertains to lubricating oil compositions stabilized against oxidation. In particular, the subject invention is directed to grease compositions having incorporated therein certain agents which inhibit oxidation of the base grease compositions.
The oxidation of lubricating oil compositions is detrimental to the wearing surfaces being lubricated. This is true not only of freely flowing lubricating oil compositions but also to thickened lubricating oil compositions.
Subsequent to their manufacture, grease compositions are stored for relatively long periods of time prior to their use as a lubricant. During these periods of storage, ordinary grease compositions tend to oxidize, yielding oxidation products which are acidic in nature. Grease compositions oxidize not only in storage but also during their use in the lubrication of wearing surfaces, forming products which are acidic in nature. The acidic products which are thus formed are detrimental to the metal surfaces to which the grease itself is finally applied. Even though such grease compositions may initially supply the necessary lubricity for wearing surfaces, such as ball and roller bearings, such wearing surfaces would be readily corroded due to the corrosive action of the oxidation products in the greases. Thus although grease compositions can lubricate bearings and other wearing surfaces, the acidic products attack the metal, causing corrosive damage to the wearing surfaces. Also, sludging caused by oxidation is detrimental to the proper lubricating of wearing surfaces.
Although the deterioration of lubricating greases by oxidation is usually slow, the partial oxidation products formed in greases catalyze the oxidation and deterioration of greases until eventually a hard, crusty material which has no lubrication value is formed. Also, such deterioration occurs much more rapidly in service than in storage, particularly since the metals such as copper and copperlead alloys further catalyze the oxidations of grease compositions.
Modern usage and increasingly severe requirements make it necessary for grease compositions to have incorporated therein oxidation inhibitors which are effective to inhibit oxidation at normal storage temperatures and also at high service temperatures. Although many oxidation inhibitors such as, for example, tertiary butyl phenol and hydroquinone, are available, they are volatile and evaporate from lubricating oil compositions at high temperatures.
Oxidation inhibitors useful for grease compositions are described in US. Patents Nos. 2,954,342 and 3,024,277. These inhibitors are alkylamides of ethylene diamine tetraacetic acid. However, the resulting grease compositions are not sufficiently inhibited against oxidation to withstand oxidation attacks at extremely high service temperatures and during conditions wherein the service requirements are severe.
Therefore, it is an object of this invention, to describe grease compositions having incorporated therein new compounds which are particularly effective for inhibiting oxidation of grease compositions at high temperatures.
In accordance with the present invention, it has been discovered that certain phenylamides of organoamine polyacetic acids are effective as oxidation inhibitors for grease compositions.
The oxidation inhibitors described herein effectively inhibit oxidation of grease compositions at high temperatures and at low temperatures.
The phenylamides of organoamine polyacetic acids of the subject invention have the following generic formula:
o R; CH,-iiN-(OH;) X-
\NRN/ II-I R2 R3 wherein R is an organo radical selected from the group consisting of cyclohexane and alkylene radicals containing from 2 to 3 carbon atoms; x is a number from 0 to 4; R R and R which may or may not be alike, are radicals selected from the group consisting of:
wherein x represents the same as that noted hereinabove. In addition, R may be selected from the group consisting of CH CH OH and and The preferred anti-oxidant described herein is the tetrabenzylamide of ethylene diamine tetraacetic acid of the formula:
0 when], Q 2 2 The phenylamine reactants are exemplified by aniline, benzylamine, phenylethylamine, phenylpropylamine, phenylbutylamine, etc.
The following specific examples illustrate the preparation of the particular amides which are used in grease compositions to inhibit oxidation thereof.
EXAMPLE I.PREPARATION OF MONOBENZYL- AMIDE OF ETHYILENE DIAMINE TETRAACE- T IC ACID A mixture of 292 g. (1 mol) of ethylene diamine tetraacetic acid, 214 g. (2 mols) of benzylamine and 900 ml. xylene was heated with agitation at temperatures of 130 to 140 C. for 16 hours. 27 ml. of water was removed by distillation. The xylene was washed out with diethyl ether. The crude product was agitated with hot dioxan. The recovered product had a melting point of 181 to 182 C., a neutralization equivalent of 177, and 9.9% nitrogen (theory= 11.0%
EXAMP-LE II.PREPARATION OF BENZYLAMIDE OF ETHY-LENE DIAMINE TETRAACETIC ACID A mixture of 292 g. ('1 mol) of ethylene diamine tetraacetic acid and 214 g. (2 mols) of benzylamine was heated with agitation for 2 hours at a temperature ranging from 160 C. to 200 C. The crude product was recrystallized from ethyl alcohol. The alcohol was removed, yielding a crude benzylamide of tetraacetic acid.
EXAIMPLE III.PREPARATION OF DIBENZYLDI- IMIDE OF ETHYLENE DIAMINE TETRAACETIC ACID The alcohol-insoluble fraction from Example II hereinabove was crystallized from dioxan, yielding a pure N,N'-dibenzyldiimide of ethylene diamine tetraacetic acid which had a melting point of 183.5 to 184.5 C, and a nitrogen content of 13.3% (theory= l2.9%).
EXAMPLE IV.PREPARATION OF TETRA-N-BEN- ZYLAMIDE OF ETHYLENE DIAMINE TETRA- ACETIC ACID A mixture of 292 g. (1 mol) of ethylene diamine tetraacetic acid and 428 g. (4 mols) of benzylamine was heated with agitation for 3 hours at temperatures ranging from 150 C. to 170 C. The crude product was crystallized from dimethyl formamide. The resulting pure tetraamide of ethylene diamine tetraacetic acid had a melting point of 176.5 C. to l77.0 C. and a nitrogen content of 12.98% (theory: 12.95%).
EXAMPLE V.PREPARATION O'F TETRAPHENYL AMIDE OF ETHY'LENE DIAMINE TETRAACE- TIC ACID A mixture of 292 g. (1 mol) of ethylene diamine tetraacetic acid and 372 g. (4 mols) of aniline, 253 g. (2.5 mols) of triethylamine, and 600 ml. of toluene was heated with agitation at temperatures from 45 C. to 80 C. for 1 hour during which time 206 g. of P01 was added slowly. The reaction mixture was filtered and water-washed until free of chlorine, yielding a crude tetraanilide of ethylene diamine tetraacetic acid.
The grease thickening agents which are used in the formation of greases in which the phenylamides of organoamine polyacetic acids may be incorporated include the organic-type grease thickening agents such as the conventional soap-type thickeners such as sodium, lithium and calcium stearates; salts of dibasic acid-diamine condensation products, such as the products of condensing a molar excess of adipic acid with hexamethylene diamine, partially neutralizing the terminal carboxyls with N-decyl amine, then forming the lithium or sodium salt thereof; salts of monoamides of terephthalic acid (e.g., sodium N-octadecyl terephthalamate); mixtures of amic acid salts such as lithium hexadecyl adiparnate and dibasic acid salts, such as lithium adipamate; ashless gelling agents, such as pyromellitirnides, etc.
Lubricating oils which can be used as base oils include a wide variety of lubricating oils, such as naphthenic base, parafiin base, and mixed base lubricating oils, other hydrocarbon lubricants, e.-g., lubricating oils derived from coal products, and synthetic oils, e.g., alkylene polymers (such as polymers of propylene, buty'lene, etc., and the mixtures thereof), alkytlene oxide-type polymers (erg. propylene oxide polymers) and derivatives thereof, including alkylene oxide polymers prepared by polymerizing the alkylene oxides in the presence of water or alcohols, e.g., ethyl alcohol, dicarboxy-lic acid esters (such as those which are prepared by esterifying such dicarboxylic acids as adipic acid, azelaic acid, suberic acid, sebacic acid, alkanol succinic acid, etc., with alcohols such as butyl alcohol, hexyl alcohol, 2-ethyl hexyl alcohol, etc.), liquid esters of acids of phosphorus, alkyl benzenes (e.g., monoalkyl benzene such as dodecyl benzene, tetradecyl benzene, etc.), polyphenyls (e.g. biphenyls and terphenyls), alkyl biphenyl ethers, polymers of silicon (e.g., tetraethyl silicate, tetraisopropyl silicates, hexyl (4-methyl-2-pentoxy) d-isiloxane, poly- (methyl) siloxane, p0ly(methylphenyl) siloxane, etc.). Synthetic oils of the alkylene oxide type polymers which may be used include exemplified by the alkylene oxide polymers.
The above base oi-ls may be used individually or in combinations thereof, wherever miscible or wherever made so by the use of mutual solvents.
The phenyl amides of organoamine polyacetic acids are used herein in lubricating. oil compositions in amounts suflicient to inhibit oxidation; that is, amounts generally between about 0.05% and 10%, by weight. For grease compositions, it is preferred to use from about 2% to 10%, by weight, more preferably, 2% to 6%, by weight, based on the finished grease composition.
Preferably, the oxidation inhibitors of this present invention are used in high temperature greases, by which is meant greases having dropping points not less than about 850 F., and which remain unctuous and do not become hard or brittle at 350 F. The oxidation inhibitors described herein are most advantageously used in high temperature greases and in high temperature serv ice because of their low volatility, their stability, and their marked effectiveness at high temperatures.
The tables set forth herein-below present data showing the effectiveness of the amides described herein as oxidation inhibitors in lubricating oil compositions.
In grease compositions, unless otherwise noted, the base grease used was a California base oil thickened with 12% sodium N-octadecyl terephthalamate.
The :Thin Film Test measures the ability of the grease composition to maintain grease like characteristics; particularly, retention of pliability and resistance to oxidation underexposure of a thin film of grease to high temperatures. The test also indicates other grease characteristics, such as tendency to bleed, flake, (some greases, although soft and greasy, crack and break), and tendency to become tacky. The Thin Film Test was run as follows. The grease to be tested was coated on a metal strip. The grease coating was of uniform dimensions: thick, 4;" wide, and 2 /2 long. This grease sample was placed in an oven at 350 F. and observed at periodic intervals until the sample no longer existed as a grease. The life of the grease was the number of hours during which the grease sample was so heated before it lost its grease-like: characteristics; that is, the time at which the test sample began to become hard and brittle.
The Bearing Life for a particular grease composition was determined by the following test procedure, which is known as the Army-Navy High Speed Bearing Test. In this test, a ball bearing packed full of grease W38. operated at i10,000 rpm. continuously for approximately 22 hours at 350 F. The apparatus was then cooled to Table l Amine Used for Amide Preparation Grease Characteristics:
Thin Film Life (Hrs) Bomb Oxidation, p.s.i. drop at- 24 Hrs 48 Hrs 100 Hrs 200 Hrs 300 Firs 400 Hrs Bearing Life (Hrs.)*
* Geometric Mean of 3 Tests.
(:1) No Amide--Base Grease Alone.
Tables 11 and III hereinbelow show the effect on the oxidation resistance of grease compositions using two different batches of the base grease described hereinabove, containing benzylamide of ethylene diamine tetraacetic acid prepared by varying the mol ratio of benzylamide (BZA) to ethylene diamine tetraacetic acid (EDTA) in the amide preparation, forming the mono benzylamide, the di benzylam-ide, the tetrabenzylamide of ethylene diamine tetraacetic acid, etc.
The benzylamide of EDTA was used in the same amounts of 5% by weight.
Table II M01 Ratio BZA to EDTA (a) (b) 2:1 2:1 3+:1
(Amide) (Imide) Grease Characteristics:
Bomb Oxidation, p.s.i. drop at- 100 Hrs- 63+ 11 26 22 18 200 Hrs. 19 34 33 23 300 Hrs 27 41 39 26 400 Hrs 30 48 45 30 Bearing Life (Hrs) (Geometric Mean) 43 100 199 18 240 (a) Base Grease Alone. (b) Base Grease plus 5% Ethylene Diamine Tetraacetic Acid.
Table III M01 Ratio BZA to EDTA (a) 1:1 3:1 3%:1 4:1
Grease Characteristics: Bomb Oxidation, p.s.i. drop at Hrs. 82 18 28 42 55 200 Hrs. 34 47 Bearing Life (Hrs) (Geometric Mean) 110 324 535 (a) Base Grease Alone.
Tables IV and V hereinbelow set forth data showing further the effectiveness of the new additives of this invention as oxidation inhibitors for greases.
Base grease A was a bis(2-ethyl hexyl) sabacate oil thickened with 15% lithium stearate.
Base grease B was a California base mineral oil thick- Table IV Grease Composition, wt. percent:
1. Base Grease A 2. Base Grease B 51 Amide o Grease Characteristics:
1. Bomb Oxidation (250 F.) (p.s.i. drop at lOOh 65 26 40 2 Bearing Life (300 F 1 can) 74 280 650 550 Table V Grease Composition, wt. percent:
1. Base Grease Grease Characteristics:
1. Bomb Oxidation (250 F.) (p.s.i.
drop at hours) 28 29 82 38 2. Bearing Life (300 F.) (Geometric Mean) 200 Table VI hereinbelow presents data showing the effectiveness of the new oxidation inhibitors herein in automatic transmission fluids.
With the exception noted, the lubricating oil compositions were tested according to The Federal Specification Test VV-L-791D, Amendment 1, Method 53.8.2. Whereas this method specifies an oil temperature of 300 F., the data hereinbelow were obtained at 350 F.
Water-saturated air previously heated to 100 F. was bubbled through 300 cc. of the oil to be tested for a period of hours at a rate of 8 liters per hour, using copper and iron wire as catalyst. The temperature of the oil was maintained at 350 F. The viscosity increase of the oil was noted.
Oil A was a California base oil containing 0.4% by weight of a zinc dialkyl dithiophosphate and 0.4% of a commerically used phenolic antioxidant.
Oil B was the same California base oil containing 0.4% by weight, of a zinc dialkyl dithiophosphate and 0.1% of a mixture of triand tetrabenzyl amides of ethylene diamine tetraacetic acid.
Table VI Oil A Oil B Viscosity Increase, Percent 40 17 wherein R is an organo radical selected from the group consisting of cyclohexane and alkylene of from 2 to 3 carbon atoms, R and R are selected from the group consisting of CH CO H and and R is selected from the group consisting of -CH CO H 6. An oxidation inhibited lubricating oil composition comprising a major proportion of an oil of lubricating viscosity and from 0.05 to weight percent of an amide of an organoamine polyacetic acid of the formula 1 011,0 ONHOHz and wherein R is an organo radical selected from the group consisting of cyclohexane and alkylene of from 2 to 3 carbon atoms, R and R are selected from the group consisting of CH CO H and and R is selected from the group consisting of 8 --CH2CO2H 7. An oxidation inhibited grease composition consisting essentially of grease compositions thickened with an organic type grease thickening agent and containing from 2 to 10 weight percent of an amide of an organo-amine polyacetic acid of the formula NRN 2 a wherein R is an organo radical selected from the group consisting of cyclohexane and alkylene of from 2 to 3 carbon atoms, R and R are selected from the group consisting of -CH CO H and -on,ooNHoH,
and R is selected from the group consisting of CH CO H -oH,o oNnom and and
8. A grease composition according to claim 7, wherein said amide is tetrabenzylamide of 1,2-cyclohexane dinitrilotetraacetic acid.
9. A grease composition according to claim 7, wherein said amide is tribenzylamide of 1,2-cyclohexane dinitrilotetraacetic acid.
10. A grease composition according to claim 7, wherein A said amide is pentabenzylamide of diethylenetrinitn'lopentaacetic acid.
11. A grease composition according to claim 7, wherein said amide is tetrabenzylamide of ethylenediamine tetraacetic acid.
References Cited by the Examiner UNITED STATES PATENTS 9/60 Hotten 25233.6 3/62 Hotten 252--5l.5
DANIEL E. WYMAN, Primary Examiner.