CA1038394A

CA1038394A - Lubricant compositions

Info

Publication number: CA1038394A
Application number: CA206,359A
Authority: CA
Inventors: Daniel G. Jones
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1973-08-07
Filing date: 1974-08-06
Publication date: 1978-09-12
Also published as: NL7410585A; IT1017942B; AU7215674A; GB1469479A; DE2437842A1; FR2240229A1; FR2240229B1; ZA744882B; JPS5071705A

Abstract

ABSTRACT OF THE DISCLOSURE
Organic lubricant compositions are provided containing a lubricating improving amount of a salt of an acid phosphonate of the formula:

Description

This invention relates to lubricant additives and to lubricating oils and greases with improved anti-~ear and fric-tion properties.
It is well known that certain types of lubricant compositions, particularly oils of lubricating viscosities and greases normally exhibit poor anti-wear properties during the courseof their performance, as well as requiring friction modi-f~ing improvement. In this respect, it has previously been proposed that certain phosphorus acid esters should be used to improve the properties of lubricants. Tri-cresyl phosphate, for example, is well known as an anti-wear agent, particular-ly in synthetic ester aviation fluids. The use of certain acid phosphates in lubricants is described in U.S. Patents 3,116,284, 3,116,249, 2,72~,728, 2,801,968 and 2,285,853. The use of certain phosphites or phosphonates, as they are various-ly referred to, is described in U.S. Patents 3,115,466 and

2,824,131 and British Patent Specification 899,101.
The use of amine salts of certain phosphorus acids has also previously been proposed in U.S. Patents 2,674,616, 2,874,120, 2,838,332 and 3,634,239. Canadian Patent 668,735 describes the use of imidazoline/phosphate salts.
We have now found that the imidazoline salts of certain long chain alkyl acid phosphonates provide improve-ments in the anti-wear and friction properties of lubricating oils and greases.
These salts are derived from (a) an imidazoline which is substituted by a straight chain aliphatic graup of 12 to 22 carbon atoms, and (b) a (Cl to C4 alkyl) hydrogen (C12 to C22 straight chain alkyl) phosphonate.
The phosphonates which are reacted with the imidazo-- 1 - q~;

~ .

.~,~ .

lQ38394 line are acid phosphonates of the formula:
OR' R - P - O
¦ OH
where R is a long chain alkyl group of 12 to 22,- preferably 18, carbon atoms, and R' is an alkyl group (Cl-C4), preferably methyl. The preferred acid phosphonate is methyl hydrogen octadecylphosphonate, of the formula:
f CH3 C H P- O
OH
Acid phosphonates of this type are also referred to as alkyl alkylphosphonic acids. See "Phosphorus and its Compounds", vanWazer, Interscience, N.Y., Vol. I, p. 350.
The salts may be prepared by reacting the phosphon-ate with the desired imidazoline in stoichiometric proportions.
The reaction is normally carried out at ambient temperature, although elevated temperatures may be employed for accelera-ting the reaction.
The imidazolines which may be used contain a long chain (C12-C22) aliphatic group which may be saturated or unsaturated. Such imidazolines may be prepared by the reaction of a carboxylic acid with a polyamine which, for present purposes, is preferably a diamine, especially ethylene diamine.
The carboxylic acid provides the desired long chain group and thus, acids with C12-C22 aliphatic groups on the carboxyl groups may be used to prepare the imidazoline~

,.. , ~ , . .
~ J

1~38394 A particularly preferred material is the l-hydroxy-ethyl-2-alkyl-imidazoline in which the al~yl group is derived from oleic acid. This material can be produced by reacting ethylene diamine with oleic acid to form the imidazoline ring structure and then reacting the product with ethylene oxide to produce the hydroxyethyl substituent.

N ~ CH2 -- C17H33.COoH + H2NC2H4NH2 >
7 IH2 o Cl7H33-C~ ~CH2 + C ~CH2 N - CH2 N Cl7H33-C CH2 H N

Other substituted imidazolines may be made in the same way, using other amines and acids. For example, diethylene triamine, triethylene tetramine and tetraethylene pentamine may be used as amines and stearic, dodecanoic, hexadecanoic, linoleic and linolenic acids may be used as the acids.
Since the purpose of the acid is to provide the long chain alkyl group which renders the product oil soluble, straight chain acids containing from 12 to 22 carbon atoms in the chain may be used. The chain may be saturated as in stearic acid or unsaturated as in oleic acid. If the imidazoline is produced from ethylene diamine and therefore contains an ~Q38394 active hydrogen, it may be reacted with an alky}ene oxide, preferably ethylene oxide although propylene oxide is also contemplated, to produce a substituent hydroxyalkyl group on ¦ the imidazoline ring as shown above.
It ha~ been found that if the long chain group of the imidazoline contains less than 12 carbon atoms, little or no improvement in friction-modifying properties is realized.
On the other hand, if the alkyl group contains more than 22 carbon atoms, the resulting salt is found to be less soluble in the lubricants.
Lubricant compositions containing the additives of this invention may comprise a major amount of a lubricant base and a minor amount of the additive salt, preferably in an amount from 0.2 to 1.5~ by weight, and for most applica-tions, from 0.4 to 1%, by weight, of the total weight of the composition.
The lubricant compositions may comprise any materials that normally exhibit insufficient anti-wear properties or which require friction-modifying characteristics.
A field of specific applicability is the improvement of liquid hydrocarbon oils boiling within the range from 75F
to 1000F.

~,...

Mineral lubricating oils, improved in accordance with the present invention may be of suitable lubricating viscosity range from 45 to 6000 SSU at 100F. (5.3 to 1300 CS. at 38C) and, prefera~ly, from 50 to 250 SSU at 210F. (7.4 to 53 CS.
at 99C) These oils may have viscosity indexes varying from below 0 to 100 or higher. Viscosity indexes from 70 to 95 are preferred. The average molecular weights of these oils may r~nge from 250 to about 800. In general, the lubricant may comprise any mineral or synthetic oil of lubricating vi~coslty.
The salts of the present invention may be incorpor-ated as friction modifiers or anti-wear agents in grease compositions also. Such greases may comprise a combination of a wide variety of lubricating vehicles and thickening or gelling agents. Thus, greases in which the aforementioned salts are particularly effective, may comprise any of the afore-mentioned hydrocarbon oils of lubricating viscosity, as the oil vehlcle, and may include mineral or synthetic lubricating oils, and, particularly of the types hereinbefore described.
When high temperature stability is not a requirement of the finished grease, mineral oils having a viscosity of at least 40 SSU at 150F., (4.2 cS at 66C) and particularly those falling within the range from 60 SSU to 6000 SSU at 100F.
(10 to 1300 cS at 38C) may be employed. The lubricating vehicles are combined with a grease-forming quantity of a thickening agent. For this purpose, a wide variety of materials may be employed. These thickening or gelling agents include metal salts and soaps, non-soap thickeners, such as surface-modified clays and silicas, aryl ureas, I

~ ~ -5-1/~38394 calcium complexes and similar materials. In general, grease thickeners which do not melt and dissolve when used at the required temperature within a particular environment are preferred.
The following data and examples will serve to illustrate the novel alkylamine salts of the present invent`~n and . .

~A

10383g4 their efficacy as lubricant improvers in anti-wear and friction modifying characteristics in organic lubricant compositions.
It will be understood, however, that it i5 not intended the invention be limited to the particular additives as described and that various modifications thereof can be employed and will be readily apparent to those skilled in the art.

Example l In the comparative runs of this example, the additive package component comprised, by weight: zinc dithiophosphate 1%, polymethyl methacrylate 3.3%~ aromatic oil swelling agent 2%, kerosene 0.1%, calcium sulfonate 8.6~, synthetic sulfurized sperm oil 3%. In this example and in the remaining examples the base oil comprised a solvent-refined paraffin base oil stock dewaxed to a 0F. pour point.

~38394 Formulation Material, Wt. % Run A Run B
Base Oil 81.75 81.50 Additive package 18.00 18.00 Methyl octadecyl acid phosphonate 0.25 0.25) l-hydroxy ethyl-2-alkylimidazoline )*
of oleic acid 0.00 0.25) *Reacted before blending Test Results SA~ Wear Test, 680607, 76 RPM
I50 lbs., 1/2 hr.
-Weight loss, mg Fail in 10 Min. 12 Assessment Fail Pass IHC Water Tolerance Test 14 days with 1% water Separation of additive, Vol. ~ 0.2 None The comparative data of the foregoing example illus-trates the improved anti-wear and water tolerance properties imparted by the alkylamine salts of the present invention.

Example 2 -In the comparative runs of this example, the additive package component comprised, by weight, the same additive package employed in Example 1 except that the sulfurized sperm oil was o~itted.

.

1038;3 94 Formulation Material, Wt. % Run A Run B
Base Oil 84.50 84.50 Additive package 15.00 15.00 Methyl octadecyl acid phosphonate 0.50 0.25~
l-hydroxy ethyl-2-alkylimidazoline )*
~f oleic acid 0.00 0.25) *Reacted before blending Test Results SAE Wear Testj 680607, 76 RPM, Weight loss, mg 19 5 Assessment Pass Pass IHC Water Tolerance Test - 51% Water) Additive separation after 14 days, Vol. % O O
Additive separation after 21 days, Vol. % o.6 0 Additive separation after 28 days, Vol. % o.8 0 The comparative data of the foregoing example illus-trates the improved anti-wear and water tolerance properties imparted by the alkylamine salts of the present invention.

Example 3 In the comparative runs of this example, the additive package component comprised, by weight: zinc dithiophosphate ~7~, polymethyl methacrylate 3%, aromatic oil swelling agent 2%, . kerosene 0.1%, calcium sulfonate 7%. The John Deere Tractor

3 Chatter Index test is fully described in U.S. Patent 3,652,410.

Formulation ~ ~38394 Material, Wt. % Run ~ Run B
Base Oil 86.70 86.70 Additive package 12,80 12.80 Methyl octadecyl acid phosphonate 0.50 0.25 l-hydroxy ethyl-2-alkylimidazoline *
of oleic acid 0.00 0.25 *Reacted before blending Test Results John Deere Tractor Chatter Index 184 186

4-Ball Wear Scar, mm (40 kg, 2 hrs., 200F., 600 rpm) 0.50 0.45 The comparative data of the foregoing example illus-trates the improved anti-wear performance and equivalent chatter control imparted by the alkylamine salts of the present invention.

Example 4 In the comparative runs of this example, the additive package component comprised, by weight: polymethyl methacrylate 2.4%, sulfurized isobutylene 1.8%, polybutenyl succinimide of tetraethylpentamine 1%, kerosene 0.75%, alkyl ester of alkyl dithioph~sphoric acid 0.2%, alkyl derivative of 2,5 dimercapto 1,3,4 thiadiazole 0.1%.

Formulation Material, Wt. % Run A Run B
Base Oil 93.25 93.25 Additive package 6~25 6.25 Methyl octadecyl acid phosphonate 0.50 0.25 l-hydroxy ethyl-2-alkyllmidazoline *
of oleic acid 0.00 0.25 *Reacted before blending Test Results Precipitate after 30 days storage Heavy None at room temperature The comparative data of the foregoing example illus-trates the inefficacy of the methyl octadecyl acid phosphonate, as a free acid, in forming a precipitate after 30 days.

Example 5 In the comparative runs of this example, the additive package component comprised, by weight: polymethyl methacrylate 2.4%, sulfurized isobutylene 1.8%, polybutenyl succinimide of tetraethylpentamine 1.0%, alkyl ester of alkyl dithiophosphoric acid 0.2%, dibutylphosphonate 0.4%, kerosene 0.75%, alkyl derivative of 2,5 dimercapto 1,3,4 thiadiazole 0.1%.

~ 038394 Formulation Material, Wt. % Run A Run B
Base Oil 93.35 92.85 Additive package 6.65 6.65 Methyl octadecyl acid phosphonate 0.00 0.25) l-hydroxy ethyl-2-alkylimidazoline ~*
of oleic acid 0.00 0.25 ~Reacted be~ore blending Test ~esults -John Deere Oxidation Test ~00 hrs. at ~OOUF.) % Viscosity change at 210F. 4.30 2.74 % Viscosity change at 100F. 12.44 7.41 Humidity Cabinet, 120F.
Hours to rust 24 48 The comparative data of the foregoing example illus-trates the improved performance in areas of oxidative stability and anti-rust properties imparted by the alkylamine salts of the present invention.

Example 6 In the comparative runs of this example, the additive package component comprised, by weight: polymethyl methacrylate 2.4~o~ polybutenyl succinimide of tetraethylpentamine 1.0%, barium sulfonate 1.0%, alkyl ester of aryl dithiophosphoric acid 2%, kerosene 0.1%.

Formulation 1~394 Material, Wt. % Run A Run B
Base Oil 93 50 93.oo Additive package 6.50 6.50 Methyl octadecyl acid phosphonate 0;00 0.25) l-hydroxy ethyl-2-alkylimidazoline )*
of oleic acid 0.00 0.25) ~Reacted before blending Test Results Humidity Cabinet, 120F.
Rating at 96 hours Fail Pass SAE Wear Test 76 RPM, 150 lbs. wt. 106s, m~. Failed at 150 lbs 74 156 " , 400 " Failed at 180 lbs.877 The comparative data of the foregoing example illus-trates the improvement in anti-wear and anti-rust performance ~ lmparted by the alkylamine salts of the present invention.
Example 7 In the comparative runs ofthisexample the additlve package component comprised, by weight, 0.70% of a zinc dialkyl dlthiophosphate, 3.30% of a methacrylate polymer viscosity index improver, 2.00% of a hi~h boiling aromatic seal swell agent, 0.10% of a silicone defoamant solution (in kerosene), 8.60% of a calcium overbased petroleum sulfonate.
~he compositions shown below were tested and the results were as shown (the amine reactant and the acid phosphonate pre-reacted):
Run No.
Formulation (Wt. %) 1 2 3 4 Base Stock 85.30 84.80 84.85 84.84 Additive packa~e 14.70 14.70 14.70 14.70 Methyl octadecyl acid 2 0 25 0 25 phosphonate -- O. 5 Oleyl imidazoline ~- 0.25 -- --Oleylamine ~~ -- 0.20 --Dimethylsoya amine ~ 0.21 1~38394 Test Results Catalytlc Oxidation, air/hr.
Increasein 210P~ --y ~ 6.8 5.8 4.1 6.7 IHC Water Tolerance ------------~~-(1% Water) , ` ~~_ ~ - ~ ~~
Additive separation ~~~ ~~
after 21 days None None None None Humldity Cabinet,120F
Rating at 96 Hrs. Pass Pass Pass Pass SAE Wear Test 7~ RPM, 150 lbs. Pass Pass Pass Pass ! . LVFA Borg-Warner SD 715 Paper on Steel Coefficient of Static Friction at 200F 0.136 0.120 0.125 0.130 ~ .... . . . . .
While preferred embodiments of the novel organic , .
lubricant compositions of the present invention have been des-cribed for the purpose of illustration, it will be understood I that various modifications and adaptations thereof, which will i be obvious to those skilled in the art, may be made without departing from the spirit of the invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A salt of an acid phosphonate of the formula:
where R is an alkyl group of 12 to 22 carbon atoms and R' is an alkyl group of 1 to 4 carbon atoms and an imidazoline which is substituted by a straight chain aliphatic group of 12 to 22 carbon atoms.

2. A salt according to claim 1, in which the acid phosphonate has the formula:
wherein R is an alkyl group of 12 to 18 carbon atoms.

3. A salt according to claim 2, in which the acid phosphonate is methyl hydrogen octadecylphosphonate.

4. A salt according to claim 1, in which the imidazoline is obtained by reacting ethylenediamine and a carboxylic acid containing a C12-C22 straight chain aliphatic group attached to the carboxyl group.

5. A salt according to claim 4, in which the imidazoline is obtained by reaction of the ethylenediamine with the carboxylic acid followed by reaction with ethylene oxide.

6. A salt according to claim 4, in which the carboxylic acid is oleic acid.

7. A salt according to claim 5 or 6, in which the imidazoline has the formula:

8. The salt of methyl hydrogen octadecylphosphonate and 1-2-(hydroxyethyl)-2-oleyl-2-imidazoline.

9. A lubricant composition comprising a major pro-portion of a lubricant base and a minor proportion of a salt as defined in claim 1.

10. A lubricant composition comprising a major proportion of a lubricant base and a minor proportion of a salt as defined in claim 2.

11. A lubricant composition comprising a major proportion of a lubricant base and a minor proportion of a salt as defined in claim 3.

12. A lubricant composition comprising a major proportion of a lubricant base and a minor proportion of a salt as defined in claim 4.

13. A lubricant composition comprising a major proportion of a lubricant base and a minor proportion of a salt of an acid phosphonate of the formula:
where R is an alkyl group of 12 to 22 carbon atoms and R' is an alkyl group of 1 to 4 carbon atoms and an imidazoline of the formula:

14. A lubricant composition comprising a major proportion of a lubricant base and a minor proportion of a salt as defined in claim 8.

15. A lubricant composition according to claim 9, which includes from 0.2 to 1.5 percent by weight of the salt.

16. A lubricant composition according to claim 9, which includes from 0.4 to 1.0 percent by weight of the salt.

17. A lubricant composition according to claim 9, 15 or 16, which is a lubricating oil.

18. A lubricant composition according to claim 9, 15 or 16, which is a grease.

19. A lubricant composition according to claim 13 or 14, which is a lubricating oil.

20. A lubricant composition according to claim 13 or 14, which is a grease.