EP0684978B1

EP0684978B1 - Lubricant composition containing alkoxylated amine salts of acids

Info

Publication number: EP0684978B1
Application number: EP94909034A
Authority: EP
Inventors: Jacob Joseph Habeeb; Morton Beltzer
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1993-02-22
Filing date: 1994-02-22
Publication date: 1997-05-21
Anticipated expiration: 2014-02-22
Also published as: DE69403322T2; CA2156608A1; WO1994019434A1; DE69403322D1; EP0684978A1; JPH09504040A

Abstract

Lubricant oil compositions useful for reducing friction in an internal combustion engine comprise a lubricating oil basestock and an alkoxylated amine salt of an acid, said salt having formula (I), wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group having from 2 to 22 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20 and n is from 1 to 3.

Description

This invention relates to lubricant compositions containing alkoxylated amine salts of hydrocarbylsalicylic acids, trithiocyanuric acid, hydrocarbylsulfonic acids, dihydrocarbyldithiophosphoric acids or dihydrocarbyldithiobenzoic acids and to the use of such salts to reduce friction and/or improve fuel economy in an internal combustion engine.
There are many instances, as is well known, particularly under "Boundary Lubrication" conditions where two rubbing surfaces must be lubricated, or otherwise protected, so as to prevent wear and to insure continued movement. Moreover, where, as in most cases, friction between the two surfaces will increase the power required to effect movement and where the movement is an integral part of an energy conversion system, it is most desirable to effect the lubrication in a manner which will minimize this friction. As is also well known, both wear and friction can be reduced, with various degrees of success, through the addition of a suitable additive or combination thereof, to a natural or synthetic lubricant. Similarly, continued movement can be insured, again with varying degrees of success, through the additional of one or more appropriate additives.
The primary oil additive for the past 40 years for providing antiwear and antioxidant properties has been zinc dialkyldithiophosphate (ZDDP). Oil formulations containing ZDDP, however, require friction modifiers in order to reduce energy losses in overcoming friction. Such energy losses result in lower fuel economy. Oil additive packages containing ZDDP have environmental drawbacks. ZDDP adds to engine deposits which can lead to increased oil consumption and emissions. Moreover, ZDDP is not ash-free. Various ashless oil additive packages have been developed recently due to such environmental concerns. A further drawback with ZDDP is that it contains phosphorous which poisons the catalytic converters for cars.
In order to protect internal combustion engines from wear, engine lubricating oils have been provided with antiwear and anti-oxidant additives. For example, U.S. Patent 4,575,431 discloses a lubricating oil additive composition containing dihydrocarbyl hydrogen dithiophosphates and sulfur-free hydrocarbyl dihydrogen phosphates and dihydrocarbyl hydrogen phosphates, said composition being at least 50% neutralized by a hydrocarbyl amine having 10 to 30 carbons in said hydrocarbyl group. U-S. Patent 4, 089,790 discloses an extreme-pressure lubricating oil containing (1) hydrated potassium borate, (2) an antiwear agent selected from (a) ZDDP, (b) an ester, an amide or an amine salt of a dihydrocarbyl dithiophosphoric acid or (c) a zinc alky aryl sulfonate and (3) an oil-soluble organic sulfur compound.
U.S. Patent No. 5,076,945 discloses a lubricating oil composition containing an amine salt of a dithiobenzoic acid. The amines used to prepare the salts are long chain hydrocarbyl amines.
U.S. Patents 3,849,319 and 3,951,973 describe lubricant compositions containing di- and tri(hydrocarbylammonium)trithio-cyanurates. The hydrocarbyl radicals include alkyl, aralkyl, aryl, alkaryl and cycloalkyl and the examples are directed to alkylamines. These lubricant compositions were stated to have improved load-carrying properties.
WO 91/14756 describes additive compositions having utility in metal working lubrication comprising alkoxylated amine salts of dihydrocarbyldithiophosphoric acid which may be diluted with oil to form concentrates which contain from 5 to 90% by weight of the additive compositions.
It would be desirable to have a lubricating oil composition which provides excellent friction reducing and/or fuel economy properties and provide environmentally beneficial (less fuel, i.e., less exhaust emission) properties. A further benefit would be compositions which contain less phosphorous.
This invention relates to lubricant compositions containing alkoxylated amine salts of hydrocarbylsalicylic acids, trithiocyanuric acid, hydrocarbylsulfonic acids, dihydrocarbyldithiophosphoric acids or dihydrocarbyldithiobenzoic acids having improved friction reducing properties which results in improved fuel economy In an internal combustion engines. In the case of salts other than those derived from dihydrocarbyldithiophosphoric acids there is the added advantage of the salts being substantially free of phosphorous which can poison the catalytic converters of cars. Also some of the salts e.g. dihydrocarbyldithiobenzoic acid derived salts have antiwear and antioxidant activity.
The present invention therefore provides a lubricating oil composition for internal combustion engines which comprises (a) a major amount of a lubricating oil basestock and (b) a minor amount of an alkoxylated amine salt of an acid said salt having the general formula 1-.
wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group having from 2 to 22 carbon atoms with the proviso that when Z is derived from a hydrocarbylsalicylic acid R is an alkyl or alkenyl group of from 6 to 18 carbon atoms and when Z is derived from a hydrocarbylsulfonic acid that R is a hydrocarbyl group of from 6 to 18 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20 and n is 1 or from 1 to 3 preferably 3 when the acid is trithiocyanuric acid and that when Z in formula I is derived from a dihydrocarbyldithiophosphoric acid that the concentration of the resultant salt in the lubricating oil composition is 0.001 to about 5.0 wt%, provided that said concentration is not 5.0 wt %.
The invention further provides a lubricating oil composition for internal combustion engines which comprises

(a) a major amount of a lubricating oil basestock and
(b) a minor amount of an alkoxylated amine salt of an acid said salt having the general formula I:
wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group having from 2 to 22 carbon atoms with the proviso that when Z is derived from a hydrocarbylsalicylic acid R is an alkyl or alkenyl group of from 6 to 18 carbon atoms and when Z is derived from a hydrocarbylsulfonic acid that R is a hydrocarbyl group of from 6 to 18 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20 and n is 1 or from 1 to 3 preferably 3 when the acid is trithiocyanuric acid and that when Z in formula I is derived from a dihydrocarbyldithiophosphoric acid that the concentration of the resultant salt in the lubricating oil composition is 0.001 to less than 2.0 wt %.

In a further aspect the present invention provides for the use, for reducing friction and/or improving fuel economy in an internal combustion engine, of an alkoxylated amine salt having the formula (1) set forth.
In the lubricating oil composition of the present invention, the lubricating oil will contain a major amount of a lubricating oil basestock. The lubricating oil basestocks are well known in the art and can be derived from natural lubricating oils, synthetic lubricating oils, or mixtures thereof. In general, the lubricating oil basestock will have a kinematic viscosity ranging from 5 to 10,000 cSt at 40°C, although typical applications will require an oil having a viscosity ranging from about 10 to 1,000 cSt at 40°C.
Natural lubricating oils include animal oils, vegetable oils (e.g., castor oil and lard oil), petroleum oils, mineral oils, and oils derived from coal and shale.
Synthetic oils include hydrocarbon oils and halo-substituted, hydrocarbon oils such as polymerized and interpolymerized olefins, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologs thereof, and the like. Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers and derivatives thereof wherein the terminal hydroxyl groups have been modified by esterification, etherification, etc. Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids with a variety of alcohols. Esters useful as synthetic oils also include those made from C₅ to C₁₂ monocarboxylic acids and polyols and polyol ethers.
Silicon-based oils (such as the polyakyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils) comprise another useful class of synthetic lubricating oils. Other synthetic lubricating oils include liquid esters of phosphorous-containing acids, polymeric tetrahydrofurans, polyalphaolefins, and the like.
The lubricating oil may be derived from unrefined, refined, rerefined oils, or mixtures thereof. Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment. Refined oils are similar to the unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties. Suitable purification techniques include distillation, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art. Rerefined oils are obtained by treating refined oils in processes similar to those used to obtain the refined oils. These rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.
The amine salts of the acids are prepared from the reaction of alkoxylated, preferably propoxylated or ethoxylated, most preferably ethoxylated amines with the acid. Preferred ethoxylated amines used to prepare amine salts have the formula
where R is hydrocarbyl group of from 2 to 22 carbon atoms, preferably 6 to 18 carbon atoms. The hydrocarbyl groups include aliphatic (alky or alkenyl) groups which may be substituted with hydroxy, mercapto, amino and the like and the hydrocarbyl group may be interrupted by oxygen, nitrogen or sulfur. The sum of x + y is preferably 2 to 15. Ethoxylated and/or propoxylated amines are commercially available from Sherex Chemicals under the trade name Varonic and from Akzo Corporation under the trade names Ethomeen®, Ethoduomeen®, and Propomeen®. Examples of preferred amines containing from 2 to 15 ethoxy groups include ethoxylated (5) cocoalkylamine, ethoxylated (2) tallowalkylamine, ethoxylated (15) cocoalkylamine and ethoxylated (5) soyaalkylamine.
Prefered hydrocarbylsalicylic acids used to react with alkoxylated amines to form amine salts have the following formula:
wherein R¹ is a hydrocarbyl group having from 2 to 30 carbon atoms preferably a hydrocarbyl group of from 2 to 26 carbon atoms. Such hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic groups. The aliphatic and alicyclic groups may be substituted with hydroxy, alkoxy, cyano, nitro and the like and the alicyclic group may contain O, S or N as hetero atoms. These substituted salicylic acids are commercially available or may be prepared by methods known in the art, e.g. U.S. Patent 5,023,366.
Trithiocyanuric acid may exist in different tautomeric forms represented by formulas II, III or mixtures thereof:
Trithiocyanuric acid is prepared by methods well known in the art. These methods involve the treatment of cyanuric chloride with sulfur nucleophiles according to the following reaction scheme:
Other sulfur nucleophiles which may be employed in the above reaction scheme include sodium sulfide, thiourea and thioacetic acid.
Prefered hydrocarbylsulfonic acids used to react with alkoxylated amines to form amine salts have the following formula:
wherein R¹ is preferably a hydrocarbyl group having from 2 to 30 and most preferably having from 2 to 26 carbon atoms. Such hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic groups. The aliphatic and alicyclic groups may be substituted with hydroxy, alkoxy, cyano, nitro and the like and the alicyclic group may contain O, S or N as hetero atoms. These sulfonic acids are commercially available or may be prepared by methods well known in the art.
Preferred dihydrocarbyldithiophosphoric acids used to react with alkoxylated amines to form amine salts have the following formula:
wherein R¹ and R² are independently hydrocarbyl groups having from 3 to 30 carbon atoms, preferably 3-20 carbon atoms. Such hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic groups. The aliphatic and alicyclic groups may be substituted with hydroxy, alkoxy, cyano, nitro and the like and the alicyclic group may contain O, S or N as hetero atoms. Especially preferred are dialkyldithiophosphoric acids made from mixed (85%) 2-butyl alcohol and (15%) isooctylalcohol (mixed primary and secondary alcohols). Dihydrocarbyldithiophosphoric acids are commercially available from Exxon Chemical Company.
Preferred dihydrocarbyldithiobenzoic acids used to reacted with alkoxylated amines to form amine salts have the following formula:
wherein R² to R⁶ are each preferably hydrogen; a hydrocarbyl group containing from 1 to 18 carbon atoms or a hydroxy group with the proviso that at least one of R² to R⁵ is a hydrocarbyl group, preferably an alkyl group containing 1 to 18 carbon atoms, more preferably 1 to 6 carbon atoms. R³ and R⁵ are most preferably t-butyl groups and R⁴ is most preferably hydroxy. The hydrocarbyl groups include aliphatic (alky or alkenyl) and alicyclic groups which may be substituted with hydroxy, mercapto, amino and the like and the hydrocarbyl group may be interrupted by oxygen, nitrogen or sulfur.
Dithiobenzoic acids may be prepared from a phenol according to the following method. A phenol of the formula:
is dissolved in a solvent such as dimethylsulfoxide and treated under nitrogen with potassium hydroxide dissolved in a minimum of water. Carbon disulfide is added under nitrogen to this mixture which is maintained at about room temperature. The resulting reaction mixture is heated at between 25 to 100°C for 1-3 hours and then added to an acidified water solution. The resulting dithiobenzoic acid can be isolated by solvent extraction using, e.g. ether and the solvent evaporated.
The alkoxylated amine salts according to the present invention are prepared by methods known to those skilled in the art. The preparative reaction scheme is illustrated as follows:
wherein R, n, x and y are defined as above.
Approximately equimolar amounts of alkoxylated amine and acid are mixed together in an acid/base neutralization reaction. The amounts of acid or base may be varied to achieve the desired acid/base balance of the final amine salt.
The lubricant oil compositions according to the present invention comprises a major amount of lubricating oil basestock and a minor amount of the alkoxylated amine salt. Typically, the amount of amine salt will be from 0.001 wt% to 5 wt%, based on oil basestock, except where it is derived from a dihydrocarbyldithiophosphoric acid. Preferably, the amount of amine salt is from 0.05 wt% to 1.0 wt%. When the amine salt is derived from a dihydrocarbyldithiophosphoric acid, the lubricant oil composition comprises a major amount of lubricating basestock and typically from 0.1 to about 5 wt%, except 5.0 wt %, and most preferably from 0.5 to 2 wt% of the salt. When the amine salt is derived from a dihydrocarbyldithiobenzoic acid it is preferred that the lubricant oil composition comprises a major amount of lubricating basestock and from 0.1 to 5 wt% and most preferably from 0.5 to 2 wt% of the salt. The amount of alkoxylated amine salt present will be an amount effective to provide reduced friction and/or improved fuel economy in internal combustion engines.
If desired, other additives known in the art may be added to the lubricating oil basestock. Such additives include dispersants, antiwear agents, antioxidants, rust inhibitors, corrosion inhibitors, detergents, pour point depressants, extreme pressure additives, viscosity index improvers, other friction modifiers, hydrolytic stabilizers and the like. These additives are typically disclosed, for example, in "Lubricant Additives" by C. V. Smalhear and R. Kennedy Smith, 1967, pp. 1-11 and in U.S. Patent 4,105,571.
The lubricating oil composition of this invention can be used in the lubrication system of essentially any internal combustion engine, including automobile and truck engines, two-cycle engines, aviation piston engines, marine and railroad engines, and the like. Also contemplated are lubricating oils for gas-fired engines, alcohol (e.g., methanol) powered engines, stationery powered engines, turbines, and the like.
This invention may be further understood by reference to the following examples, which include preferred embodiments of the present invention.

Example 1

This Example illustrates the preparation of an ethoxylated amine salt of salicylic acid according to the invention. 114 g of ethoxylated(5)cocoalkylamine was heated to 80°C with stirring in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. 100 g of salicylic acid having formula
was added gradually to the stirred amine solution. During addition, the temperature rose to 104°C due to the exothermic reaction between acid and amine. The reaction mixture was maintained at 104°C for 1.5 hours and then cooled to room temperature. The reaction mixture was that of a salt of the formula:
where x + y = 5 and was used withouth further purification.

Example 2

The ethoxylated amine salt of alkyl salicylic acid is an effective friction modifier as shown in this example. The Ball on Cylinder (BOC) friction tests were performed using the experimental procedure described by S. Jahanmir and M. Beltzer in ASLE Transactions, Vol. 29, No. 3, p.425 (1985) using a force of 0.8 Newtons (1 Kg) applied to a 12.5 mm steel ball in contact with a rotating steel cylinder that has a 43.9 mm diameter. The cylinder rotates inside a cup containing a sufficient quantity of lubricating oil to cover 2 mm of the bottom of the cylinder. The cylinder was rotated at 0.25 RPM. The friction force was continuously monitored by means of a load transducer. In the tests conducted, friction coefficients attained steady state values after 7 to 10 tums of the cylinder. Friction experiments were conducted with an oil temperature of 100°C. Various amounts of ethoxylated(5)cocoalkyl amine salicylate prepared in Example 1 were added to solvent 150 N. The results of BOC friction tests are shown in Table 1. TABLE 1

Wt% of Ethoxylated(5)Cocoalkylamine Alkyl Salicylate in Solvent 150N* Coefficient Of Friction

0.00 0.32

0.1 0.06

0.2 0.05

0.3 0.035

0.5 0.035

0.8 0.030

1.0 0.030

*S150 is a solvent extracted, dewaxed, hydrofined neutral lube base stock obtained from approved paraffinic crudes (viscosity, 32 cSt at 40°C, 150 Saybolt seconds)
As can be seen from the results in Table 1, as little as 0.1 wt% of ethoxylated amine salt shows an 81% decrease in the coefficient of friction. These results demonstrate that the ethoxylated amine salts of alkyl salicylic acids are capable of significant reductions in the coefficient of friction of a lubricant basestock which results in less friction and hence greater fuel economy when the lubricated oil is used in an internal combustion engine.

Example 3

This Example illustrates the preparation of an ethoxylated amine salt of trithiocyanuric acid according to the invention. 100 g of ethoxylated(5)cocoalkylamine was heated to 70°C with stirring in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. 14 g of trithiocyanuric acid was added gradually to the stirred amine solution. During addition, the temperature rose to 105°C due to the exothermic reaction between acid and amine. The reaction mixture was maintained at 105°C for 2 hours and then cooled to room temperature. The reaction mixture was that of a salt of the formula:
where x + y = 5 and was used without further purification.

Example 4

The ethoxylated amine salt of trithiocyanuric acid is an effective friction modifier as shown in this example. The Ball on Cylinder (BOC) friction tests were performed using the experimental procedure described in Example 2 Various amounts of ethoxylated(5)cocalkylamine trithiocyanurate prepared in Example 3 were added to solvent 150 N. The results of BOC friction tests are shown in Table 2. TABLE 2

Wt% of Ethoxylated(5)Cocoalkylamine Trithiocyanurate in Solvent 150N Coefficient Of Friction

0.00 0.29

0.05 0.16

0.10 0.076

0.20 0.06

0.30 0.05

0.50 0.05

0.80 0.05

1.00 0.05
As can be seen from the results in Table 2, as little as 0.05 wt% of ethoxylated amine salt shows a 45% decrease in the coefficient of friction. At 0.2 wt% amine salt, the coefficient is reduced by 79%. These results demonstrate that the ethoxylated amine salts of trithiocyanuric acid are capable of significant reductions in the coefficient of friction of a lubricant basestock which results in less friction and hence greater fuel economy when the lubricated oil is used in an internal combustion engine.

Example 5

This Example illustrates the preparation of an ethoxylated amine salt of sulfonic acid according to the invention. 300 g of ethoxylated(5)cocoalkylamine was heated to 60°C with stirring in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. 300 g of alkyl sulfonic acid was added gradually to the stirred amine solution. During addition, the temperature rose to 110°C due to the exothermic reaction between acid and amine. The reaction mixture was maintained at 110°C for 2 hours and then cooled to room temperature. The reaction mixture was that of a salt of the formula:
where x + y = 5 and was used without further purification. An ethoxylated(2)tallowalkylamine sulfonate salt was prepared using the same procedure from 140 g of ethoxylated(2)tallowamine and 198 g of alky sulfonic acid.

Example 6

The ethoxylated amine salt of sulfonic acid is an effective friction modifier as shown in this example. The Ball on Cylinder (BOC) friction tests were performed using the experimental procedure described in Example 2. Various amounts of ethoxylated(5)cocoalkyl amine alkylsulfonate prepared in Example 5 were added to solvent 150 N. The results of BOC friction tests are shown in Table 3. TABLE 3

Wt% of Ethoxylated(5)Cocoalkylamine Alkylsulfonate in Solvent 150N Coefficient Of Friction

0.00 0.32

0.1 0.130

0.2 0.090

0.3 0.075

0.5 0.075

0.8 0.05

1.0 0.05
As can be seen from the results in Table 3, as little as 1.0 wt% of ethoxylated salt shows an 84% decrease in the coefficient of friction. These results demonstrate that the ethoxylated amine salts of alkylsulfonic acid are capable of significant reductions in the coefficient of friction of a lubricant basestock which results in less friction and hence greater fuel economy when the lubricated oil is used in an internal combustion engine.

Example 7

The procedure of Example 6 was repeated except that ethoxylated(2)tallowalkylamine was substituted for ethoxylated(5)cocoalkylamine in the sulfonate salt. The results are shown in Table 4. TABLE 4

Wt% of Ethoxylated(5)tallowalkylamine Alkyl Sulfonate in Solvent 150N Coefficient Of Friction

0.0 0.32

0.1 0.20

0.2 0.17

0.3 0.13

0.5 0.10

0.8 0.07

1.0 0.06

These results further demonstrate that ethoxylated amine sulfonate salts are effective at reducing the coefficient of friction of a lubricant oil basestock.

Example 8

350 g of ethoxylated(5)cocoalkylamine was placed in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. The amine was stirred and heated to 50°C. A stoichiometric amount of dioctyldithiophosphoric acid was then slowly titrated into the warm amine solution with stirring. The temperature was raised to 95°C for 2 hours. The neutralization reaction was monitored with a pH meter. The addition of the acid was stopped at pH 7. After 2 hours of stirring at 95°C the reaction product was cooled to room temperature and used without further purification.

Example 9

The Sequence VI High Temperature Rapid Screen Test is a shortened version of the actual ASTM Sequence VI test for fuel economy. Although it uses the same engine as the Sequence VI, only the high temperature phase of the test is run. This emphasizes the boundary lubrication regime which basically determines the fuel economy capability of the additive. The test procedure is outlined below:

Step #	Test Sequence	Time
1	Cool down/warm up	20 min
2	Detergent Flush to Candidate Oil	1 hr, 20 min
3	Stabilize Step 1 - Stage 275°F	2 hr
4	BSFC Measurement Step 1 - Stage 275°F	30 min
5	Stabilize Step 2 - Stage 275°F	2 hr
6	BSFC Measurement Step 2 - Stage 275°F	30 min

Each candidate oil run is preceded by a flush oil run to ensure that any "carry-over" effect is eliminated. The fuel economy of the candidate oil, as measured by brake specific fuel consumption (BSFC), is measured twice in the experiment. Once after a two hour stabilization, or break-in period, and then again after another two hour stabilization period. A base oil is run periodically throughout the test to determine the test precision. In this particular test the base oil was a commercially available SAE 5W-30 oil. The results are shown in the following table. Table 5

Oil Additive % Reduction in BSFC

SAE 5W-30 -- Base case-assigned value of zero

SAE 5W-30 1% C₁₂ alkylamino:DDP* 1.46

SAE 5W-30 1% ethoxylated (5) cocoalkylamine:DDP from Example 8 5.14

* Prepared from Primene 81R® cocoamine and dioctyldithiophosphoric acid.
The data in Table 5 demonstrates that the ethoxylated amine:DDP salt shows an additional 72% improvement in BSFC over the corresponding non-ethoxylated amine:DDP salt.

Example 10

140 g of ethoxylated (5) cocoalkylamine was placed in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. The ethoxylated amine was stirred and heated to 50°C. A stoichiometic amount of 4-hydroxy-3, 5-ditertiary-butyldithiobenzoic acid (100g) was then slowly added into the warm ethoxylated amine solution with stirring. The temperature was raised to 95°C for 2 hours. The neutralization reaction was controlled with a portable pH meter. The addition of the acid was stopped at pH 7. After 2 hours of stirring at 95°C, the reaction product was cooled to room temperature and used without further purification.

Example 11

Ball on Cylinder (BOC) friction tests were performed on ethoxylated (5) cocoalkylamine:dithiobenzoate from Example 10 in solvent 150N base oil using several concentrations of the additive. The BOC tests were performed using the experimental procedure described in Example 2. The results are shown in Table 6.

Table 6

Coefficient of Friction
Pt	Concentration (wt.%) in solvent 150N base oil	Ethoxylated (5) cocoalkyamine:DTB	Primene** JMT:DTB
1	0	0.37	0.37
2	0.05	0.121	--
3	0.1	0.107	0.3
4	0.2	--	--
5	0.4	0.107	--
6	0.5	--	0.21
7	0.6	0.107	--
8	0.8	0.107	0.177

** Primene JMT is a predominantly C₁₈ t-alkyl primary amine manufactured by Rohm & Haas.

The results shown in Table 6 demonstrate that the ethoxylated (5) cocoalkylamine:dithiobenzoate salt reduces the coefficient of friction by an additional 39.5% relative to an equivalent amount of non-ethoxylated salt, thus resulting in improved fuel economy.

Claims

A lubricating oil composition for internal combustion engines which comprises
(a) a major amount of a lubricating oil basestock and

(b) a minor amount of an alkoxylated amine salt of an acid said salt having the general formula I:
wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group having from 2 to 22 carbon atoms with the proviso that when Z is derived from a hydrocarbylsalicylic acid R is an alkyl or alkenyl group of from 6 to 18 carbon atoms and when Z is derived from a hydrocarbylsulfonic acid that R is a hydrocarbyl group of from 6 to 18 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20 and n is 1 or from 1 to 3 preferably 3 when the acid is trithiocyanuric acid and that when Z in formula I is derived from a dihydrocabyldithiophosphoric acid that the concentration of the resultant salt in the lubricating oil composition is 0.001 to about 5.0 wt%, provided that said concentration is not 5.0 wt% or above.
A lubricating oil composition for internal combustion engines which comprises
(a) a major amount of a lubricating oil basestock and

(b) a minor amount of an alkoxylated amine salt of an acid said salt having the general formula I:
wherein Z is derived from either a hydrocarbylsaicyclic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group having from 2 to 22 carbon atoms with the proviso that when Z is derived from a hydrocarbylsalicyclic acid R is an alkyl or alkenyl group of from 6 to 18 carbon atoms and when Z is derived from a hydrocarbylsulfonic acid that R is a hydrocarbyl group of from 6 to 18 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20 and n is 1 or from 1 to 3 preferably 3 when the acid is trithiocyanuric acid and that when Z in formula I is derived from a dihydrocarbyldithiophosphoric acid that the concentration of the resultant salt in the lubricating oil compositon is 0.001 to 2.0 wt.%.
A composition as claimed in claim 1 or 2 wherein Z is derived from a hydrocarbylsulfonic acid of the following formula:
wherein R¹ is a hydrocarbyl group having from 2 to 30 carbon atoms.
A composition as claimed in claim 1 or 2 wherein Z is derived from a hydrocarbylsalicyclic acid of the following formula:
wherein R¹ is a hydrocarbyl group having from 2 to 30 carbon atoms.
A composition as claimed in claim 3 or claim 4 wherein R¹ is a hydrocarbyl group having from 2 to 26 carbon atoms.
A composition as claimed in claim 1 or 2 wherein Z is derived from a dihydrocarbyltdithiobenzoic acid of the following formula:
wherein R² R³ R⁴ R⁵ and R⁶ are independently hydrogen or a hydrocarbyl group containing from 1 to 24 carbon atoms or a hydroxy group with the proviso that at least one of R² to R⁵ is a hydrocarbyl group.
A composition as claimed in claim 6 wherein R⁴ is hydroxy.
A composition as claimed in either claim 6 or claim 7 wherein at least one of R² to R⁵ is alkyl containing from 1 to 18 carbon atoms.
A composition as claimed in any of claims 6 to 8 wherein R³ and R⁵ are t-butyl.
A composition as claimed in claim 1 or claim 2 wherein Z is derived from a dihydrocarbyldithiophosphoric acid which has the following general structure;
wherein R¹ and R² are each independently hydrocarbyl groups having from 3 to 30 carbon atoms.
A composition as claimed in claim 10 wherein R¹ and R² are alkyl or alkenyl of from 3 to 20 carbon atoms.
A composition as claimed in either of claims 10 or 11 wherein R in the amine is substituted with OH, SH, or NH₂ on the terminal carbon atom of the hydrocarbyl group.
A composition as claimed in any of claims 1 to 11 wherein R is alkyl or alkenyl of from 6 to 18 carbon atoms.
A composition as claimed in any of claims 1 to 13 wherein the sum of x+y is 2 to 15.
A composition as claimed in any of claims 6 to 9 wherein the amount of salt is from 0.1 to 5.0 wt.%, based on oil basestock.
A composition as claimed in any of claims 3 to 5 wherein the amount of salt is from 0.001 to 5.0 wt.%, based on oil basestock.
The use, for reducing friction and/or improving fuel economy in an internal combustion engine, of an alkoxylated amine salt set out in formula (I) as claimed in any of claims 1 to 16.
A method for reducing friction/or improving fuel economy in an internal combustion engine, which method comprises the use in such an engine of a lubricating oil composition comprising an alkoxylated amine salt set out in formula (I) as claimed in any of claims 1 to 16.