Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
LUBRICATING COMPOSITIONS COMPRISING CARBOXYLIC ACID SALT ADDITIVE, USES AND METHODS OF PREPARING
Document Type and Number:
WIPO Patent Application WO/2020/127389
Kind Code:
A1
Abstract:
The present invention relates to lubricating compositions comprising an additive metal salt or complex for imparting desirable properties to the lubricating composition, which composition is suitable for use as a lubricating composition for an engine, for example an internal combustion engine. Use of the additive metal salt or complex, as well as the lubricating compositions comprising the same, and methods of preparing the lubricating compositions are also provided. In one aspect, the invention provides a lubricating composition for an engine comprising: (i) a base oil of lubricating viscosity; (ii) an additive of formula (I) or (II), wherein: R1 is an aliphatic hydrocarbyl chain; R2 is H or Me; M represents an alkali metal, an alkaline earth metal, a transition metal, or a post-transition metal or metalloid; x is an integer from 1 to 3; and n is an integer from 1 to 5.

Inventors:
SAUER RICHARD (US)
BREAKSPEAR ANGELA (GB)
TILLOTSON MAURA (US)
Application Number:
EP2019/085803
Publication Date:
June 25, 2020
Filing Date:
December 17, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
CASTROL LTD (GB)
International Classes:
C10M129/44; C10M129/76; C10M167/00
Domestic Patent References:
WO2012087773A12012-06-28
WO2011022317A12011-02-24
WO2018007617A12018-01-11
WO1999021902A11999-05-06
WO2003099890A22003-12-04
WO2006099250A12006-09-21
Foreign References:
US2760935A1956-08-28
US2280475A1942-04-21
US2363513A1944-11-28
US20090304618A12009-12-10
US2733252A1956-01-31
US7622431B22009-11-24
US4221673A1980-09-09
US4104180A1978-08-01
US4973411A1990-11-27
EP1533362A12005-05-25
US20080293600A12008-11-27
US9624451B22017-04-18
US20050198894A12005-09-15
US20060090393A12006-05-04
Other References:
"API standard 1509", October 2013, article "ENGINE OIL LICENSING AND CERTIFICATION SYSTEM"
Attorney, Agent or Firm:
HILL, Simon, Stephen (GB)
Download PDF:
Claims:
Claims

1. A lubricating composition for an engine comprising:

(i) a base oil of lubricating viscosity;

(ii) an additive of formula (I) or (II):

wherein:

Ri is an aliphatic hydrocarbyl chain;

III is H or Me;

M represents an alkali metal, an alkaline earth metal, a transition metal, or a post-transition metal or metalloid;

x is an integer from 1 to 3; and

n is an integer from 1 to 5.

2. A lubricating composition according to Claim 1, wherein Ri is a C5 to C30 alkyl group or a C5 to C30 alkenyl group; preferably wherein Ri is a C10 to C25 alkyl group or a C10 to C25 alkenyl group; more preferably wherein Ri is a C15 to C20 alkyl group or a C15 to C20 alkenyl group.

3. A lubricating composition according to Claim 1 or Claim 2, wherein the group RiC(O)- of formula (I) or formula (II) is derived from a fatty acid, preferably a fatty acid selected from capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, arachidic acid and behenic acid, more preferably a fatty acid selected from myristic acid, palmitic acid, stearic acid and oleic acid.

4. A lubricating composition according to any one of Claims 1 to 3, wherein R2 is Me and/or wherein n is 1 or 2, preferably wherein n is 2.

5. A lubricating composition according to any one of the preceding claims, wherein M is an alkali metal selected from sodium and lithium; an alkaline earth metal selected from calcium and magnesium; or a transition metal selected from molybdenum, cobalt and titanium; or a post-transition metal or metalloid selected from boron and bismuth.

6. A lubricating composition according to Claim 5, wherein M is selected from sodium, lithium, magnesium and molybdenum, preferably wherein M is selected from sodium and molybdenum, more preferably where M is sodium.

7. A lubricating composition according to any one of the preceding claims wherein the additive of formula (I) or (II) is sodium stearoyl-2-lactylate.

8. A lubricating composition according to any one of the preceding claims, wherein the additive of formula (I) or (II) is prepared from bio-derived feedstock, preferably wherein the additive of formula (I) or (II) contains greater than 50 %, such as greater than 70 %, or greater than 90 % by weight of biobased carbon.

9. A lubricating composition according to any one of the preceding claims, wherein the additive of formula (I) or formula (II) is solubilized in the lubricating composition.

10. A lubricating composition according to any one of the preceding claims, wherein the additive of formula (I) or formula (II) is present in an amount of from 0.01 % to 5.0 %, preferably in an amount of from 0.25 % to 2.5 %, more preferably in an amount of from 0.5 % to 2.0 %, even more preferably in an amount of from 0.75 % to 1.5 %, by weight of the lubricating composition.

11. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition comprises no more than 5 % water, preferably no more than 2% water, more preferably no more than 1% water, even more preferably no more than 0.5% water, even more preferably still no more than 0.1% water, by weight of the lubricating composition.

12. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition is non-aqueous.

13. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition is free of aqueous micelles.

14. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition comprises one or more additional lubricant additives selected from detergents, friction modifiers, anti-wear additives, dispersants, viscosity modifiers, dispersant viscosity modifiers, viscosity index improvers, pour point depressants, rust inhibitors, corrosion inhibitors, anti-foams, seal swell agents, extreme pressure additives, surfactants, pour point depressants, metal deactivators, and mixtures thereof.

15. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition comprises a dispersant viscosity modifier.

16. A lubricating composition according to Claim 15, wherein the dispersant viscosity modifier is a multifunctional grafted polymer comprising a polyolefin or polyester backbone to which at least two groups of graftable monomers have been grafted, one of the at least two groups of monomers comprising ethylenically unsaturated, aliphatic or aromatic monomers having 2 to 50 carbon atoms containing oxygen or nitrogen, or both oxygen and nitrogen, the other of the at least two groups of monomers comprising primary and/or secondary amines capable of undergoing a condensation reaction with an acylating agent which has least one point of olefmic unsaturation in its structure for grafting to the polymer backbone.

17. A lubricating composition according to any one of the preceding claims, one or more dihydrocarbyl dithiophosphate metal salts, preferably in the form of zinc dihydrocarbyl dithiophosphates (ZDDP).

18. A lubricating composition according to Claim 17, wherein the one or more dihydrocarbyl dithiophosphate metal salts are present, on an elemental phosphorus basis, in amount of from 100 to 2,000 ppm, preferably in an amount of from 150 ppm to 1,000 ppm, more preferably in an amount of from 250 ppm to 500 ppm.

19. A lubricating composition according to any one of the preceding claims, wherein the lubricant composition further comprises at least one aminic anti-oxidant and/or at least one phenolic anti-oxidant.

20. A lubricating composition according to Claim 19, wherein the wherein the total combined amount of aminic and phenolic anti-oxidant in the lubricant composition is not more than 4.0 %, not more than 3.0 %, not more than 2.5 %, or not more than 2.0 % by weight of the lubricating composition.

21. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition has at least one of:

a. a kinematic viscosity at 40 °C of less than 60 cSt, such as less than 55 cSt, or less than 50 cSt;

b. a kinematic viscosity at 100 °C of less than 12 cSt, such as less than 10 cSt, or less than 9.5 cSt;

c. a viscosity index of greater than 100, such as greater than 110, or greater than

120; d. a viscosity at 150 °C and a shear rate of 106 s 1 of no greater than 3 cP, such as no greater than 2.8 cP; and

e. a Noack volatility of less than 25 %, such as no more than 20%, less than 15 %, or less than 10 % by weight.

22. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition has at least one of:

a. an oxidative stability performance on a CEC-L-088-02 and/or CEC L-l 11-16 test indicated by an absolute viscosity increase at 40 °C of no more than 45 cSt, such as no more than 35 cSt or no more than 25 cSt;

b. an oxidative stability performance on a CEC-L-109-14 test indicated by an increase in kinematic viscosity at 100 °C of less than 200 %, preferably less than 150 %;

c. a fuel economy performance on a CEC-L-054-96 test of at least 2.5 %, such as at least 3 %;

d. a piston cleanliness performance on a CEC-L-088-02 and/or CEC L-l 11-16 test indicated by an overall piston merit of at least 8.5, such as 9; and e. a high temperature stability performance on a KHT test at 280°C in accordance with JPI-5S-55-99 indicated by an overall deposit merit of at least 7.0.

23. A method of preparing a lubricating composition, said method comprising blending (i) a base oil with (ii) an additive of formula (I) or (II) as defined in any one of Claims 1 to 8 and (iii) optionally one or more additional lubricant additives.

24. A method of lubricating a surface, said method comprising supplying a lubricating composition as defined in any of Claims 1 to 22 to said surface, such as wherein the lubricating composition is supplied to a surface in an engine.

25. Use of a lubricating composition according to any of Claims 1 to 22 for lubricating a surface, such as wherein the lubricant composition is used for lubricating a surface in an engine.

26. A method of reducing the total amount of anti-oxidant additive required in a

lubricating composition to achieve a particular level of oxidative stability

performance, said method comprising adding an additive of formula (I) or (II) as defined in any one of Claims 1 to 8 to a lubricating composition comprising at least one aminic anti-oxidant and/or at least one phenolic anti-oxidant.

27. Use of an an additive of formula (I) or (II) as defined in any one of Claims 1 to 8 for reducing the total amount of anti-oxidant additive required in a lubricating

composition, the lubricating composition comprising at least one aminic anti-oxidant and/or at least one phenolic anti-oxidant, in order for the lubricating composition to achieve a particular level of oxidative stability performance.

28. A method of improving the oxidative stability performance, anti-frictional

performance, anti-wear performance, fuel economy performance and/or piston cleanliness performance of a lubricant composition comprising the step of providing or supplying to the lubricant composition at least one of the additives of formula (I) and (II).

29. Use of an an additive of formula (I) or (II) as defined in any one of Claims 1 to 8 for improving the oxidative stability performance, anti-frictional performance, anti-wear performance, fuel economy performance and/or deposit control performance of a lubricating composition.

30. A method of improving the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine, comprising the step of providing the engine and/or the vehicle with a lubricating composition according to any of Claims 1 to 22.

31. Use of a lubricating composition according to any of Claims 1 to 22 to improve the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

Description:
LUBRICATING COMPOSITIONS COMPRISING CARBOXYLIC ACID SALT

ADDITIVE, USES AND METHODS OF PREPARING

The present invention relates to lubricating compositions comprising an additive metal salt or complex for imparting desirable properties to the lubricating composition, which composition is suitable for use as a lubricating composition for an engine, for example an internal combustion engine. Use of the additive metal salt or complex, as well as the lubricating compositions comprising the same, and methods of preparing the lubricating compositions are also provided.

Background

Lubricating compositions generally comprise a base oil of lubricating viscosity together with one or more additives to deliver properties including for example, reduced friction and wear, improved viscosity index, detergency, and resistance to oxidation and corrosion. A lubricant base oil typically comprises one or more lubricating base stocks.

A combination of properties is desirable in a lubricating composition for use as an engine oil. For example, in passenger car engine oils it may be desirable for a lubricating composition to include friction modifiers and to have a low viscosity profile, since these features lead to improved fuel economy. In particular, it is desirable for a lubricating composition for use as a passenger car engine oil to have a low kinematic viscosity as well as good low-temperature viscosity characteristics, for example a low pour point or low viscosity as measured using a mini-rotary viscometer (MRV). However, formulation modifications focused on improving these properties are typically accompanied by undesirable increases in volatility, as well as an increased tendency towards deposit formation. To counteract deposit formation, the addition of detergents and dispersants is often effective. However, these additives negatively impact on fuel economy.

Medium to high temperature deposits are a well-known issue in today’s engines and can affect an engine’s overall performance with respect to fuel economy and horse power. Such deposits may be controlled by the selection of the appropriate chemistry when formulating the engine oil. To reduce the cost of engine oil approval and testing, specific deposits bench tests / fired engine tests have been developed to simulate engine conditions which have been accepted by the engine oil industry. These include TEOST (Thermo- Oxidation Engine Oil Simulation Test) MHT-4 (ASTM D-7097), TEOST 33C (ASTM D- 6335) and Sequence IIIG weighted piston deposits (WPD) tests. In formulating today’s engine oils, it is a challenge to meet the requirements of TEOST MHT-4 and TEOST 33C deposits bench tests with current industry chemistries. Traditional methods of controlling medium to high temperature deposits involve the addition of metal containing detergents, ashless dispersants and antioxidants. However, each of these additives has its associated draw backs. Metal based detergents are known to have a negative impact on fuel economy and have caused lubricant stability issues in the field. Although ashless dispersants can be effective, there becomes a point of diminishing return, particularly as they can negatively impact low temperature properties of a fully-formulated oil, necessitating the use of more costly base stocks such as GPIII or GPIV (PAO). The use of mixed antioxidant systems in conjunction with the above has proven effective on the control of deposits, although contributes significantly to overall formulation cost.

There remains a need for alternative chemistries around which lubricating compositions may be formulated which balance fuel economy with desirable lubricant oxidative stability, low temperature viscosity, volatility, deposit formation performance and overall formulation cost while also being suitable for use, for example, in a lubricating composition for an internal combustion engine.

The present invention is directed to lubricating compositions which comprise a particular additive metal salt or complex which has been found by the inventors to be particularly effective in a lubricating composition for use as an engine oil. Specifically, the additive metal salt or complex corresponds to a hydrocarbyl substituted lactylate, glycolate or lactate metal salt or complex. These salts and complexes may exhibit surfactant properties from which the benefits of this additive are believed to derive when employed in a lubricating composition or an engine oil. In particular, the additive metal salt or complex has been found to be particular useful for improving, inter alia , the oxidative stability and the anti-frictional performance of a lubricating composition and for controlling engine deposits. The additive used in accordance with the present invention therefore offers a means for preparing a lubricating composition exhibiting a desirable balance of the properties discussed hereinbefore. Another benefit of the new lubricant additive is that it is biodegradable and may be manufactured using bio-renewable feed stocks.

Summary

A lubricating composition for an engine is provided comprising:

(i) a base oil of lubricating viscosity;

(ii) an additive of formula (I) or (II): wherein:

Ri is an aliphatic hydrocarbyl chain;

R2 is H or Me;

M represents an alkali metal, alkaline earth metal, transition metal, post transition metal or metalloid;

x is an integer from 1 to 3; and

n is an integer from 1 to 5.

Also provided is a method of preparing the lubricating composition comprising the additive of formula (I) or (II).

Also provided is a method for lubricating a surface using the lubricating composition, as well as the use of the lubricant composition for lubricating a surface.

Also provided are methods and uses of improving the fuel economy performance and/or piston cleanliness performance of an engine and/or vehicle, as well as methods for improving the anti-frictional performance and/or anti-wear performance and/or deposit control performance of a lubricating composition.

Detailed description

A lubricating composition for an engine is provided comprising:

(i) a base oil of lubricating viscosity;

(ii) an additive of formula (I) or (II):

wherein:

Ri is an aliphatic hydrocarbyl chain; Hi is H or Me;

M represents an alkali metal, alkaline earth metal, transition metal, or a post transition metal or metalloid;

x is an integer from 1 to 3; and

n is an integer from 1 to 5.

For the purposes of the present invention, the following terms as used herein shall, unless otherwise indicated, be understood to have the following meanings.

The term "aliphatic hydrocarbyl" as used herein refers to a group comprising a major portion of hydrogen and carbon atoms, preferably consisting exclusively of hydrogen and carbon atoms, which group may be saturated or unsaturated, preferably saturated, and contains from 1 to 40 carbon atoms. Examples of hydrocarbyl groups include hydrocarbyl groups containing from 2 to 28 carbon atoms, such as from 3 to 26 carbon atoms or from 4 to 24 carbon atoms. Optionally, the hydrocarbyl group may be substituted by one or more hydroxyl (-OH) groups or one or more of the carbon atoms, and any substituents attached thereto, of the hydrocabyl group may be replaced with an oxygen atom (-0-). In some examples, the hydrocarbyl group includes from 1 to 5 hydroxyl substituents. Where one or more of the carbon atoms is replaced with -0-, in preferred examples less than 10 % of the carbon atoms are replaced with -0-, for example from 1 to 5 % of the carbon atoms are replaced. In other examples, the aliphatic hydrocarbyl group has 1 to 3 carbon atoms replaced with -0-, for example 2 carbon atoms replaced with -0-. In other examples, none of the carbon atoms are replaced with -0-. Examples of aliphatic hydrocarbyl groups include acyclic groups, non-aromatic cyclic groups and groups comprising both an acyclic portion and a non-aromatic cyclic portion. The aliphatic hydrocarbyl group may be straight chain or branched chain. The aliphatic hydrocarbyl group includes monovalent groups and polyvalent groups as specified. Examples of monovalent hydrocarbyl groups include alkyl, alkenyl, alkynyl and carbocyclyl (e.g. cycloalkyl or cycloalkenyl).

The term "alkyl" as used herein refers to a monovalent straight or branched chain hydrocarbyl moiety containing from 1 to 40 carbon atoms. Examples of alkyl groups include alkyl groups containing from 1 to 30 carbon atoms, e.g. from 1 to 20 carbon atoms, e.g. from 1 to 14 carbon atoms. Particular examples include alkyl groups containing 1, 2, 3, 4, 5 or 6 carbon atoms. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert- butyl, pentyl, hexyl and the like. Unless specifically indicated otherwise, the term“alkyl” does not include optional substituents. The term "cycloalkyl" as used herein refers to a monovalent saturated aliphatic hydrocarbyl moiety containing from 3 to 40 carbon atoms and containing at least one ring, wherein said ring has at least 3 ring carbon atoms. The cycloalkyl groups mentioned herein may optionally have alkyl groups attached thereto. Examples of cycloalkyl groups include cycloalkyl groups containing from 3 to 16 carbon atoms, e.g. from 3 to 10 carbon atoms. Particular examples include cycloalkyl groups containing 3, 4, 5 or 6 ring carbon atoms. Examples of cycloalkyl groups include groups that are monocyclic, polycyclic (e.g. bicyclic) or bridged ring system. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.

The term "alkenyl" as used herein refers to a monovalent straight or branched chain unsaturated hydrocarbyl group containing from 2 to 40 carbon atoms and containing, in addition, at least one carbon-carbon double bond, of either E or Z configuration unless specified. Examples of alkenyl groups include alkenyl groups containing from 2 to 28 carbon atoms, e.g. from 3 to 26 carbon atoms, e.g. from 4 to 24 carbon atoms. Particular examples include alkenyl groups containing 2, 3, 4, 5 or 6 carbon atoms. Examples of alkenyl groups include ethenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3- pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl and the like.

The term“alkylene” refers to a divalent straight or branched chain saturated hydrocarbyl group consisting of hydrogen and carbon atoms and containing from 1 to 30 carbon atoms. Examples of alkylene groups include alkylene groups that contain from 1 to 20 carbon atoms, e.g. from 1 to 12 carbon atoms, e.g. from 1 to 10 carbon atoms. Particular examples include alkylene groups that contain 1, 2, 3, 4, 5 or 6 carbon atoms.

The term“post-transition metal or metalloid” refers to a metallic element, or an element exhibiting metallic properties, which is located generally to the right of the transition metals, such as spanning Groups 11 to 16, preferably Groups 12 to 15, of the periodic table and which is capable of forming a complex with lactylate, glycolate and lactate anions.

Examples of post-transition metal or metalloid elements include B, Zn, Ga, Ge, Cd, In, Sn, Sb, Hg, Ti, Pb, Bi, and Po.

In accordance with the present invention, M may be selected from an alkali metal, an alkaline earth metal, a transition metal, or a post-transition metal or metalloid. In preferred embodiments, M is selected from an alkali metal or an alkaline earth metal.

Examples of preferred alkali metals include Na and Li.

Examples of preferred alkaline earth metals include Ca and Mg. Examples of preferred transition metals include Mo, Co and Ti.

Examples of preferred post-transition metals or metalloids include B, Ga, In, Sn, Ti,

Pb and Bi. Most preferably the post-transition metal or metalloid is B or Bi.

In other preferred embodiments, M is selected from Na, Li, Ca, Mg, Mo, Co, B, Ti and Bi.

x is an integer from 1 to 3 and represents the positive charge of the cation of metal element, M, as well as the number of single-charged anionic counterions which form a salt or complex with the metal cation, M x+ , in formula (I) and (II). As an example, where M is magnesium and forms a Mg(II) cation, x would be 2 giving a Mg 2+ cation complexed with two single-charged anionic counterions. Preferably, x is 1 or 2.

n is an integer from 1 to 5 and corresponds to the number of repeat units of the lactylate group (where R 2 is Me) or glycolate group (where R 2 is H) of formula (I). In preferred embodiments, n is an integer from 1 to 3. More preferably, n is 1 or 2. Most preferably, n is 2.

In preferred embodiments, Ri is a C 5 to C 30 alkyl group or a C 5 to C 30 alkenyl group; preferably wherein Ri is a C 10 to C 25 alkyl group or a C 10 to C 25 alkenyl group; more preferably wherein Ri is a C 15 to C 20 alkyl group or a C 15 to C 20 alkenyl group.

As will be appreciated, when R 2 of formula (I) is Me, then the group inside the round brackets corresponds to a lactylate group. Where R 2 is Me, the carbon to which R 2 is attached constitutes a stereogenic centre within the compound of formula (I). Either (R) or (S) enantiomers may be present at this stereogenic centre of the lactylate group of the compound of formula (I). Any combination of diastereomers resulting from the presence of more than one lactylate group (where n > 1) are also covered by formula (I) of the present invention. In contrast, where R 2 of formula (I) is H, then the group inside the round brackets in formula (I) corresponds to a glycolate group and no stereogenic centre is associated with that portion of the compound.

A particular advantage of the present invention is that the additive salt or complex of formula (I) or formula (II) may be derived from a biological source. For example, the group RiC(O)- of formula (I) or formula (II) may be derived from a fatty acid obtained from a glyceride oil deriving from a biological source. Where the group RiC(O)- of formula (I) or formula (II) is derived from a fatty acid, the fatty acid is preferably selected from capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, arachidic acid and behenic acid. More preferably, the fatty acid is selected from myristic acid, palmitic acid, stearic acid and oleic acid, most preferably the fatty acid from which the group RiC(O)- of formula (I) or formula (II) derives is stearic acid.

In preferred embodiments, the additive of formula (I) or (II) is prepared from bio derived feedstock, more preferably wherein the additive of formula (I) or (II) contains greater than 50 %, such as greater than 70 %, or greater than 90 % by weight of biobased carbon.

In preferred embodiments, the additive salt or complex is of formula (I). More preferably, R2 in formula (I) is Me, corresponding to an additive salt or complex which includes a lactylate group. In particularly preferred embodiments, where R2 is Me (i.e. where a lactylate group is present) n is 1 or 2, more preferably n is 2.

In particularly preferred embodiments, the additive of formula (I) is an alkali metal or alkaline earth metal stearoyl-2-lactylate, more preferably sodium stearoyl-2-lactylate.

The lubricating composition of the present invention may contain an amount of additive of formula (I) or (II) which is sufficient to impart beneficial properties of the additive onto the lubricant composition. In preferred embodiments, the additive of formula (I) or formula (II) is present in the lubricating composition in an amount of from 0.01 % to 5.0 % by weight of the lubricating composition. More preferably, the additive of formula (I) or formula (II) is present in the lubricating composition in an amount of from 0.25 % to 2.5 %, even more preferably in an amount of from 0.5 % to 2.0 %, and most preferably in an amount of from 0.75 % to 1.5 %, by weight of the lubricating composition.

The additive of formula (I) or (II) may be present in any form which is capable of imparting a benefit to the lubricating composition. For example, the additive may be suspended or solubilized in the lubricating composition. Preferably, the additive of formula (I) or formula (II) is solubilized in the lubricating composition.

The lubricating composition according to the present invention is suitable for use in an engine, preferably an internal combustion engine which is, for instance, associated with an automotive vehicle. As will be appreciated, the lubricating composition must be suitable for that intended use in terms of formulation (i.e. fluid properties) and composition (i.e. stability, consistency, performance and compatibility with an engine).

In preferred embodiments, the lubricating composition comprises no more than 5 % water, more preferably no more than 2% water, even more preferably no more than 1% water, still more preferably no more than 0.5% water, and still more preferably no more than 0.1% water, by weight of the lubricating composition. Most preferably, the lubricating composition is non-aqueous. In other preferred embodiments, the lubricating composition is free of aqueous micelles.

An additive of formula (I) or formula (II) may readily be obtained commercially, since such compounds are well known in the food and personal care industries. For example, additives of formula (I) or (II) may be obtained from RITA Corporation (Illinois, USA) or Corbion (Kansas, USA). Alternatively, such compounds may instead be prepared by methods familiar to the skilled person. For example, US 2009/0304618 describes methods for preparing acyl lactylates by reacting a fatty acid and lactic acid with a base such as sodium hydroxide. US 2,733,252 describes methods involving the reaction of acyl chlorides with lactic acid or a polylactic acid, as well as preferred methods involving heating fatty acids with lactic acid or polylactic acid in the presence of catalytic quantities of alkali metal or alkaline earth metal ions. Similar methods may also be used for forming acyl glycolates, where lactic acid is replaced with glycolic acid. The skilled person is able to modify the method of preparation based on the nature of the intended hydrocarbyl group (Ri) and the anionic group of the additive of formula (I) and (II).

The lubricating composition of the present invention may contain more than one additive of formula (I) and/or (II). Nevertheless, for ease of manufacture, it is preferred that only a single additive of formula (I) or (II) is included in the lubricating composition of the invention.

The additive of formula (I) or (II) may be present in any form which is capable of imparting a benefit to the lubricating composition. For example, the additive may be suspended or solubilized in the lubricating composition. Preferably, the additive of formula (I) or formula (II) is solubilized in the lubricating composition.

A particular advantage of the present invention relates to the oxidative stability and anti-frictional performance conferred to the lubricating composition by the presence of an additive of formula (I) or (II). These benefits have been found to be obtainable without negatively impacting upon other properties of the lubricating composition. Additives of formula (I) and formula (II) are readily soluble in base oils intended for lubrication of an engine and no negative impact on deposits formation has been observed as result of their inclusion. Indeed, the presence of an additive of formula (I) or formula (II) has resulted in fewer deposits being generated in the Thermo-oxidation Engine oil Simulation Test (TEOST) 33C test compared to a baseline formulation differing only by their absence. The TEOST 33C test, which corresponds to standard method ASTM D6335, is a bench test which simulates the oxidation and carbonaceous deposit-forming characteristics of engine oils in the turbochargers of modern high-performance engines. The TEOST 33C test generates physical measurements of deposits and represents a test through which to determine an oil’s susceptibility to deposit formation, particularly in the turbochargers of the engine. Lubricating compositions according to the invention have been found to outperform a baseline formulation differing only in the absence of an additive of formula (I) or (II) in the TEOST 33C test, indicating that the additive of formula (I) and (II) confers a high temperature stability on the lubricating composition. This effect has been found to mirror the effect of increasing the treat rate of anti-oxidants in the fully formulated lubricating composition, in the absence of an additive of formula (I) or (II). This indicates that the additive of formula (I) or (II) is also capable of improving the oxidative stability of the lubricating composition.

It is desirable for lubricating compositions to exhibit good oxidation stability, particularly when used in an internal combustion engine where oxidative degradation is exacerbated as a result of the high temperatures encountered in an engine. Good oxidation stability can extend the useful lifetime of a lubricant composition, for instance, by reducing oxidative thickening, which can otherwise rapidly lead to a loss of fuel economy, as well as increasing deposit and sludge formation which may otherwise ultimately result in engine failure. Typically, oxidation stability of a lubricating composition is improved by the addition of anti-oxidants. An antioxidant level representative of a high performance engine oil may exceed 3.0 wt.%, by weight of the lubricating composition. Thus, a significant proportion of the composition may be made up of anti-oxidants and therefore these represent a significant cost component of the lubricant composition. Common anti-oxidants used in lubricating compositions for use in an internal combustion engine include phenolic and aminic anti oxidants. However, the presence of phenolic anti-oxidants is known to have detrimental environmental effects whilst the presence of aminic anti-oxidants has been found to contribute to turbo-charger deposits, piston varnish and copper corrosion and can also cause problems with elastomer compatibility. Negative interactions between a lubricant composition and oil seals that are found in engines may, in some cases, lead to loss of lubricant through failure of the oil seals.

Another advantage of the additive of formula (I) or (II) used in accordance with the present invention is therefore that it confers oxidative stability to the lubricating composition to an extent that it may in turn lower the amount of anti-oxidant, particularly phenolic and aminic antioxidants, that would otherwise be required in order to obtain satisfactory oxidative stability performance.

The present invention also therefore provides the use of an additive of formula (I) or (II) for reducing the total amount of anti-oxidant additive required in a lubricating composition, the lubricating composition comprising at least one aminic anti-oxidant and/or at least one phenolic anti-oxidant, in order for the lubricating composition to achieve a particular level of oxidative stability performance.

The present invention also provides a method of reducing the total amount of anti oxidant additive required in a lubricating composition to achieve a particular level of oxidative stability performance, said method comprising adding an additive of formula (I) or (II) to a lubricating composition comprising at least one aminic anti-oxidant and/or at least one phenolic anti-oxidant.

In preferred embodiments, where the lubricating composition of the invention comprises aminic and/or phenolic anti-oxidants, the total combined amount of the aminic and phenolic anti-oxidant in the lubricant composition may be not more than 4.0 %, not more than 3.0 %, not more than 2.5 %, or not more than 2.0 % by weight of the lubricating composition.

The base oil component of the lubricating composition of the invention may be made up of base stocks. Lubricant base stocks used in automotive engine lubricants are generally obtained from petrochemical sources, for example they may be obtained as the higher boiling fractions isolated during the refining of crude oil or as the products of chemical reactions of feedstocks from petrochemical sources. Lubricant base stocks can also be made from Fischer- Tropsch wax.

Lubricant base stocks may be classified as Group I, II, III, IV and V base stocks according to API standard 1509, "ENGINE OIL LICENSING AND CERTIFICATION SYSTEM", 17 th Edition, Annex E (October 2013 with Errata March 2015), as set out in Table

1 Table 1

Group I base stocks are typically manufactured by known processes including, for example, solvent extraction and solvent dewaxing, or solvent extraction and catalytic dewaxing. Group II and Group III base stocks are typically manufactured by known processes including, for example, catalytic hydrogenation and/or catalytic hydrocracking, and catalytic hydroisomerisation. Group IV base stocks include for example, hydrogenated oligomers of alpha olefins.

The base oil of the lubricating composition may comprise a single base stock or a combination of base stocks selected for example from Group I, Group II, Group III, Group IV and Group V base stocks. In some embodiments, the lubricating composition comprises greater than about 50 %, such as greater than about 65 %, or greater than about 80 % by weight of base oil.

The additives of formula (I) and (II) may be used to improve the oxidative stability, anti-friction performance, anti-wear performance, fuel economy performance and/or piston cleanliness performance of a lubricant composition, and/or the fuel economy performance and/or piston cleanliness performance of an internal combustion engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine. Accordingly, there are provided methods of improving the oxidative stability, anti-friction performance, anti- wear performance, fuel economy performance and/or piston cleanliness performance of a lubricant composition comprising the step of providing or supplying to the lubricant composition at least one of the additives of formula (I) and (II). Furthermore, there are also provided methods of improving the fuel economy performance and/or piston cleanliness performance of an internal combustion engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine, comprising the step of providing or supplying to the engine and/or vehicle at least one of the additives of formula (I) and (II).

In addition to the additive of formula (I) or (II), the lubricating composition typically comprises at least one additional lubricant additive. The lubricating composition may thus comprise a single lubricant additive, in addition to the additive of formula (I) or formula (II) though it will typically comprise a combination of additional lubricant additives. The lubricant additives will typically be present in the lubricant composition in an amount of from about 5 % to about 40 % by weight, such as about 10 % to about 30 % by weight.

Suitable lubricant additives include detergents (including metallic and non-metallic detergents), friction modifiers, dispersants (including metallic and non-metallic dispersants), viscosity modifiers, dispersant viscosity modifiers, viscosity index improvers, pour point depressants, anti-wear additives, rust inhibitors, corrosion inhibitors, antioxidants (sometimes also called oxidation inhibitors), anti-foams (sometimes also called anti-foaming agents), seal swell agents (sometimes also called seal compatibility agents), extreme pressure additives (including metallic, non-metallic, phosphorus containing, non-phosphorus containing, sulphur containing and non-sulphur containing extreme pressure additives), surfactants, metal deactivators, and mixtures of two or more thereof.

In some embodiments, the lubricating composition comprises a detergent. Examples of detergents include ashless detergents (that is, non-metal containing detergents) and metal- containing detergents. Suitable non-metallic detergents are described for example in US 7,622,431. Metal-containing detergents comprise at least one metal salt of at least one organic acid, which is called soap or surfactant. Suitable organic acids include for example, sulphonic acids, phenols (suitably sulphurised and including for example, phenols with more than one hydroxyl group, phenols with fused aromatic rings, phenols which have been modified for example, alkylene bridged phenols, and Mannich base-condensed phenols and saligenin-type phenols, produced for example by reaction of phenol and an aldehyde under basic conditions) and sulphurised derivatives thereof, and carboxylic acids including for example, aromatic carboxylic acids (for example hydrocarbyl-substituted salicylic acids and derivatives thereof, for example hydrocarbyl substituted salicylic acids and sulphurised derivatives thereof).

In preferred embodiments, metallic and non-metallic phenate and neutral sulphonate detergents may be used as additives in the lubricating composition of the invention.

Neutral and overbased metal phenate detergents are well-known for their use as lubricant additives (overbased compounds containing more than the stoichiometric amount of metal required to react with the phenol in order to prepare the metal phenate). Metal phenates include alkali or alkaline earth metal phenates, preferably wherein the metal is selected from barium, sodium, potassium, lithium, calcium, and magnesium, most preferably calcium and magnesium. Phenols employed in the preparation of phenate detergents include hydrocarbyl substituted phenols, such as para-substituted phenols, phenols with more than one hydroxyl group, phenols with fused aromatic rings and/or alkylene bridged biphenols, any of which may be sulphurised (for example, mono- and di-sulphide bridged biphenols). Suitable phenate detergents for use in the present invention include those described, for example, in US 4,221,673, US 4,104, 180 and US 4,973,411.

The phenate detergent may have a base number (BN) of from 0.1 to 400 mg KOH/g, or from 50 to 200 mg KOH/g, for example 150 mg KOH/g, as measured in accordance with ASTM D2896. In preferred embodiments, an overbased phenate detergent is employed having a base number (BN) of from 150 to 400 mg KOH/g, preferably 200 to 300 mg KOH/g, for example from 240 to 260 mg KOH/g, as measured in accordance with ASTM D2896.

Neutral metal sulphonate detergents are well-known for their use as lubricant additives and include alkali or alkaline earth metal sulphonates, preferably wherein the metal is selected from barium, sodium, potassium, lithium, calcium, and magnesium, most preferably calcium and magnesium. Neutral sulphonates for use in the present invention may have a TBN of less than 60 mg KOH/g, preferably less than 40 mg KOH/g, as measured in accordance with ASTM D2896. Suitably sulphonates may be prepared from sulfonic acids which are typically obtained by the sulphonation of alkyl substituted aromatic hydrocarbons, such as those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl or their halogen derivatives such as chlorobenzene, chlorotoluene and chloronaphthalene. The alkyl substituted aryl sulphonates typically contain from about 9 to about 80 or more carbon atoms, preferably from about 16 to about 60 carbon atoms.

In some embodiments, the lubricating composition comprises a friction modifier. Suitable friction modifiers include for example, ash-producing additives and ashless additives. Examples of suitable friction modifiers include fatty acid derivatives including for example, fatty acid esters, amides, amines, and ethoxylated amines. Examples of suitable ester friction modifiers include esters of glycerol for example, mono-, di-, and tri-oleates, mono-palmitates and mono-myristates. A particularly suitable fatty acid ester friction modifier is glycerol monooleate. Examples of suitable friction modifiers also include molybdenum compounds for example, organo molybdenum compounds, molybdenum dialkyldithiocarbamates, molybdenum dialkylthiophosphates, molybdenum disulphide, tri molybdenum cluster dialkyldithiocarbamates, non-sulphur molybdenum compounds and the like. Suitable molybdenum-containing compounds are described for example, in EP 1533362 A1 for example in paragraphs [0101] to [0117]

In some embodiments, the lubricant composition comprises a dispersant. Examples of suitable ashless dispersants include oil soluble salts, esters, amino-esters, amides, imides and oxazolines of long chain hydrocarbon-substituted mono- and polycarboxylic acids or anhydrides thereof; thiocarboxylate derivatives of long chain hydrocarbons; long chain aliphatic hydrocarbons containing polyamine moieties attached directly thereto; Mannich condensation products formed by condensing a long chain substituted phenol with formaldehyde and polyalkylene polyamine; Koch reaction products and the like. Particularly preferred dispersants for use in the present invention are long chain aliphatic hydrocarbons containing polyamine moieties attached directly thereto such as polyisobutylene succinyl anhydride-polyamines (PIBSA-PAM).

In preferred embodiments, the lubricating composition comprises a dispersant viscosity modifier. It has surprisingly been found that the balance of kinematic viscosity (KV) at 100 °C and high temperature, high shear (HTHS) viscosity is particularly favourable when the lubricating composition comprises both an additive of formula (I) or (II) and a dispersant viscosity modifier. In formulating a lubricating composition, it is desirable to seek reductions in KV since these correlate with improved fuel economy. However, reductions in KV are typically accompanied by corresponding reductions in HTHS viscosity. Higher HTHS viscosity values correspond with a better ability of a lubricating composition to protect and lubricate engine parts, such as the cam shaft. Therefore, reductions in HTHS are undesirable.

It has been found that the presence of an additive of formula (I) or (II) in the lubricating composition in combination with a dispersant viscosity modifier is effective at reducing the KV at 100 °C of the composition. However, surprisingly, it has also been found that where a dispersant viscosity modifier is present in combination with the additive of formula (I) or (II), little or no reduction of HTHS viscosity is observed. Reducing the KV at 100 °C whilst retaining a comparable HTHS viscosity value is particularly desirable since this indicates that improvements in fuel economy may be achieved without loss in lubrication performance. These benefits have not been found to be achievable when either the additive of formula (I) or (II), or the dispersant viscosity modifier, is present in the absence of the other. This strongly suggests that there is a synergistic interaction between the additive of formula (I) or (II) and the dispersant viscosity modifier.

The effects of the combination of the additive of formula (I) or (II) and the dispersant viscosity modifier have not been found to be replicated by substituting a viscosity modifier for the dispersant viscosity modifier, even where the dispersant viscosity modifier is replaced with a viscosity modifier sharing the same polymer backbone. Thus, it is believed that the functionalization of the polymer which provides the enhanced performance associated with a dispersant viscosity modifier over conventional viscosity modifiers is also responsible for providing the surprising synergy with the additive of formula (I) or (II).

Any form of dispersant viscosity modifier may be used as an additive in the lubricating composition of the present invention. A preferred class of dispersant viscosity modifier is a multifunctional grafted polymer containing two groups of monomers grafted to a polyolefin or polyester backbone, one group of monomers to impart dispersancy as well as another group of monomers to impart soot handling as described in US 2008/0293600 and US 9,624,451, for example, the contents of which are incorporated herein by reference.

Generally, one group of monomers comprising ethylenically unsaturated, aliphatic or aromatic monomers having 2 to about 50 carbon atoms containing oxygen or nitrogen, or both oxygen and nitrogen are contemplated for use as graftable monomers imparting dispersancy which is associated with sludge and varnish handling. Another group of monomers, the "graftable coupling agents" such as the "acyl group", which can provide acyl groups for reaction, reacts with amines forming substituents suitable for imparting soot handling performance. In general, the amines are comprised of primary and secondary amines that can undergo a condensation reaction with an appropriate acylating agent (an agent that introduces an acyl group (R-C(=0)-) into a molecule). The acylating agent has at least one point of olefmic unsaturation in its structure, preferably where the point of olefmic unsaturation is a- or b- to a carboxy functional group, olefmically unsaturated mono-, di-, and polycarboxylic acids, the lower alkyl esters thereof, the halides thereof, and the anhydrides thereof represent typical acylating agents that may be used in this aspect the olefmically unsaturated acylating agent is a mono- or dibasic acid, or a derivative thereof such as anhydrides, lower alkyl (C 1 -C 7 ) esters, halides and mixtures of two or more such derivatives.

The acylating agent may include at least one member selected from the group consisting of monounsaturated C4 to C50, alternatively C4 to C20, alternatively C4 to C10, dicarboxylic acids, monounsaturated C3 to C50, alternatively C3 to C20, alternatively C3 to C10, monocarboxylic acids and anhydrides thereof (that is, anhydrides of those carboxylic acids or of those monocarboxylic acids), and combinations of any of the foregoing acids and/or anhydrides.

Suitable acylating agents include acrylic acid, crotonic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid, methylcrotonic acid, sorbic acid, 3-hexenoic acid, 10-decenoic acid, 2-pentene- 1,3,5 - tricarboxylic acid, cinnamic acid, and lower alkyl (e.g., Ci to C4 alkyl) acid esters of the foregoing, e.g., methyl maleate, ethyl fumarate, methyl fumarate, etc. Particularly preferred are the unsaturated dicarboxylic acids and their derivatives; especially maleic acid, fumaric acid and maleic anhydride.

Amines that are suitable for reaction with the acyl group include those disclosed in, or made reference to, in US 2008/0293600, which is incorporated herein by reference in its entirety. Alkyl amines, alkylene amines, amines of molecules containing heteroatoms or heterocycles, alkylene polyamines, aromatic amines, and polyoxyalkylene polyamines may be used.

Examples of such alkyl amines, alkylene amines, alkylene polyamines and amines of molecules containing heterocycles, include methyleneamines, ethyleneamines, butyleneamines, propyleneamines, pentyleneamines, hexyleneamines, heptyleneamines, octyleneamines, N,N-dimethyaminopropyl amine, N,N-dioctylethyl amine, other polymethyleneamines, the cyclic and higher homologs of these amines such as the piperazines, the amino-alkyl-substituted piperazines, such as (2-aminopropyl)-piperazine; l,4-bis-(2-aminoethyl)piperazine, and 2-methyl- l-(2-aminobutyl)piperazine, etc. Included are also ethylene diamine, diethylene triamine, triethylene tetramine, propylene diamine, di(heptamethylene)triamine, tripropylene tetramine, tetraethylene pentamine, trimethylene diamine, pentaethylene hexamine, di(trimethylene)triamine, N-octyl-N'-methyethylene diamine, as well as other polyaminic materials. Other higher homologs obtained by condensing two or more of the above-mentioned alkyleneamines may also be used as well as heterocycles such as 3-morpholinopropylamine.

Other amine types that may be mentioned include amino-aromatic compounds such as aryl amines and alkyl aryl amine and the N-arylphenylenediamines. Specific aromatic amines include, for example, aniline, 4-morpholine aniline, benzylamine, phenylethylamine and 3- phenyl- 1 -propylamine. Among the N-arylphenylenediamines are the N- phenylphenylenediamines. Among these are N-phenyl-l,4-phenylenediamine (also referred to as 4-aminodiphenylamine), N-phenyl-l,3-phenylenediamine, N-phenyl-1,2- phenylenediamine, N-naphthyl-phenylenediamine, N-phenylnaphthalenediamine and N'- aminopropyl-N-phenylphenylenediamine. One of the more preferable amines is 4- aminodiphenylamine (also called N-phenyl-l,4-phenylenediamine).

Combinations of different amines may be used to react with one or more acylating agents. In some embodiments, the dispersant viscosity modifier is based on a multifunctional grafted polymer prepared by reacting a polymer backbone having graftable sites and an acylating agent having at least one point of olefmic unsaturation to form a graft polymer reaction product having acyl groups available for reaction, (b) reacting the reaction product of step a) with a first amine comprising an aromatic primary amine to form a graft polymer reaction product having a first functional group and acyl groups available for reaction, and (c) reacting the reaction product of step b) with a second amine comprising an aliphatic primary amine to form a graft reaction product having a first functional group and a second functional group. The method may be carried out so as to obtain a multiple function dispersant graft polymer having a Rapid ADT response of at least about 8, as described in US 9,624,451, the contents of which is incorporated herein in its entirety. Examples of suitable dispersant viscosity modifiers and methods of making them are further described in WO 99/21902, WO 2003/099890 and WO 2006/099250.

In some embodiments, the lubricating composition comprises a viscosity index improver. Examples of suitable viscosity modifiers include high molecular weight hydrocarbon polymers (for example polyisobutylene, copolymers of ethylene and propylene and higher alpha-olefins); polyesters (for example polymethacrylates); hydrogenated poly(styrene-co-butadiene or isoprene) polymers and modifications (for example star polymers); and esterified poly(styrene-co-maleic anhydride) polymers. Oil-soluble viscosity modifying polymers generally exhibit number average molecular weights of at least about 15000 to about 1000000, such as about 20000 to about 600000 as determined by gel permeation chromatography or light scattering methods.

In some embodiments, the lubricating composition comprises a pour point depressant. Examples of suitable pour point depressants include Cx to C ix dialkyl fumarate/vinyl acetate copolymers, methacrylates, polyacrylates, polyarylamides, polymethacrylates, polyalkyl methacrylates, vinyl fumarates, styrene esters, condensation products of haloparaffm waxes and aromatic compounds, vinyl carboxylate polymers, terpolymers of dialkyfumarates, vinyl esters of fatty acids and allyl vinyl ethers, wax naphthalene and the like.

In at least some examples, the at least one lubricant additive includes at least one anti wear additive. Examples of suitable anti-wear additives include non-phosphorus containing additives for example, sulphurised olefins. Examples of suitable anti-wear additives also include phosphorus-containing anti-wear additives. Examples of suitable ashless phosphorus-containing anti-wear additives include trilauryl phosphite and triphenylphosphorothionate and those disclosed in paragraph [0036] of US 2005/0198894. Examples of suitable ash-forming, phosphorus-containing anti-wear additives include dihydrocarbyl dithiophosphate metal salts. Examples of suitable metals of the dihydrocarbyl dithiophosphate metal salts include alkali and alkaline earth metals, aluminium, lead, tin, molybdenum, manganese, nickel, copper and zinc. Particularly suitable dihydrocarbyl dithiophosphate metal salts are zinc dihydrocarbyl dithiophosphates (ZDDP).

It has surprisingly been found that there are particular benefits to the anti-frictional performance associated with a lubricating composition in having both an additive of formula

(I) or (II) and an anti-wear additive, in particular dihydrocarbyl dithiophosphate metal salts, for example zinc dihydrocarbyl dithiophosphates (ZDDP). In particular, it has been found that the coefficient of friction observed for a lubricating composition is significantly improved by having both an additive of formula (I) or (II) in combination with a dihydrocarbyl dithiophosphate metal salt such as ZDDP. Both the additive of formula (I) or

(II) and the dihydrocarbyl dithiophosphate metal salt have been found to independently lower the coefficient of friction exhibited by lubricating compositions comprising them, when for instance tested in the High Frequency Reciprocating Rig (HFRR) Tests. However, unexpectedly, the respective effects in reducing the coefficient of friction have been found to be at least additive when the additive of formula (I) or (II) and the dihydrocarbyl dithiophosphate metal salt are present in the lubricating composition at the same time. This suggests that both additives achieve their effects by different mechanisms, each of which neither diminishing nor interfering with the beneficial effects of the other. This is particularly advantageous in a lubricating composition where re-formulating or introducing a new additive can have unforeseen detrimental effects on the action of other components within the composition.

Thus in preferred embodiments, the lubricating composition comprises one or more dihydrocarbyl dithiophosphate metal salts, for example ZDDP. Preferably, the one or more dihydrocarbyl dithiophosphate metal salts are present, on an elemental phosphorus basis, in amount of from 100 to 2,000 ppm, preferably in an amount of from 150 ppm to 1,000 ppm, more preferably in an amount of from 250 ppm to 500 ppm.

In some embodiments, the lubricating composition comprises a rust inhibitor. Examples of suitable rust inhibitors include non-ionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, polyoxyalkylene polyols, anionic alky sulphonic acids, zinc dithiophosphates, metal phenolates, basic metal sulphonates, fatty acids and amines.

In some embodiments, the lubricating composition comprises a corrosion inhibitor. Examples of suitable corrosion inhibitors include phosphosulphurised hydrocarbons and the products obtained by the reaction of phosphosulphurised hydrocarbon with an alkaline earth metal oxide or hydroxide, non-ionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, thiadiazoles, triazoles and anionic alkyl sulphonic acids. Examples of suitable epoxidised ester corrosion inhibitors are described in US 2006/0090393.

In some embodiments, the lubricating composition comprises an antioxidant. Examples of suitable antioxidants include alkylated diphenylamines, N-alkylated phenylenediamines, phenyl-a-naphthylamine, alkylated phenyl-a-naphthylamines, dimethylquinolines, trimethyldihydroquinolines and oligomeric compositions derived therefrom, hindered phenolics (including ashless (metal-free) phenolic compounds and neutral and basic metal salts of certain phenolic compounds), aromatic amines (including alkylated and non-alkylated aromatic amines), sulphurised alkyl phenols and alkali and alkaline earth metal salts thereof, alkylated hydroquinones, hydroxylated thiodiphenyl ethers, alkylidenebisphenols, thiopropionates, metallic dithiocarbamates, 1,3,4- dimercaptothiadiazole and derivatives, oil soluble copper compounds (for example, copper dihydrocarbyl thio- or thio-phosphate, copper salts of a synthetic or natural carboxylic acids, for example a Cx to C ix fatty acid, an unsaturated acid or a branched carboxylic acid, for example basic, neutral or acidic Cu(I) and/or Cu(II) salts derived from alkenyl succinic acids or anhydrides), alkaline earth metal salts of alkylphenolthioesters, suitably containing C5 to C12 alkyl side chains, calcium nonylphenol sulphide, barium t-octylphenyl sulphide, dioctylphenylamine, phosphosulphised or sulphurised hydrocarbons, oil soluble phenates, oil soluble sulphurised phenates, calcium dodecylphenol sulphide, phosphosulphurised hydrocarbons, sulphurised hydrocarbons, phosphorus esters, low sulphur peroxide decomposers and the like. In some embodiments, the lubricating composition comprises an antifoam agent. Examples of suitable anti-foam agents include silicones, organic polymers, siloxanes (including poly siloxanes and (poly) dimethyl siloxanes, phenyl methyl siloxanes), acrylates and the like.

In some embodiments, the lubricating composition comprises a seal swell agent.

Examples of suitable seal swell agents include long chain organic acids, organic phosphates, aromatic esters, aromatic hydrocarbons, esters (for example butylbenzyl phthalate) and polybutenyl succinic anhydride.

The lubricant composition may comprise lubricant additives in the amounts shown in Table 2.

Table 2

The lubricating compositions may have a kinematic viscosity at 40 °C of less than about 60 cSt, such as less than about 55 cSt, or less than about 50 cSt. The lubricant compositions may have a kinematic viscosity at 100 °C of less than about 12 cSt, such as less than about 10 cSt, or less than about 9.5 cSt. The lubricant compositions may have a viscosity index of greater than about 100, such as greater than about 110, or greater than about 120. The kinematic viscosity at 40 °C and the kinematic viscosity at 100 °C may be measured according to ASTM D445. The viscosity index may be calculated according to ASTM D2270.

The lubricating compositions may have a Noack volatility of less than about 25 %, such as less than about 15 %, or less than about 10 % by weight. Noack volatility may be measured according to CEC-L-40- A-93.

The lubricating compositions may have a viscosity at 150 °C and a shear rate of 10 6 s 1 of no greater than 3 cP, such as no greater than 2.8 cP. This high temperature high shear viscosity may be measured according to CEC-L-36-A-90.

The lubricating composition may have at least one of:

an oxidative stability performance on a CEC-L-088-02 and/or CEC L- 111-16 test indicated by an absolute viscosity increase at 40 °C of no more than 45 cSt, such as no more than 35 cSt or no more than 25 cSt; a fuel economy performance on a CEC-L-054-96 test of at least 2.5 %, such as at least 3 %; a piston cleanliness performance on a CEC-L-088-02 and/or CEC L-l 11-16 test indicated by an overall piston merit of at least 8.5, such as 9; and a high temperature stability performance on a KHT test at 280 °C in accordance with JPI-5S- 55-99 indicated by an overall deposit merit of at least 7.0.

The lubricating compositions may have a cold-crankcase simulator performance to satisfy a SAE J300 Standard specification.

The lubricant compositions may be used in a method of lubricating a surface, such as the surface of an engine.

Suitable surfaces include those in power transmission systems for example drive lines and gear boxes for example for vehicles including for example passenger vehicles and heavy duty vehicles; and those in internal combustion engines, for example the crankcases of internal combustion engines. Suitable surfaces also include those in turbine bearings for example in water turbine bearings.

Suitable internal combustion engines include, for example, engines used in automotive applications, engines used in marine applications and engines used in land-based power generation plants. The lubricant compositions are particularly suited to use in an automotive internal combustion engine.

The lubricating compositions may be used to improve the fuel economy and/or piston cleanliness performance of an internal combustion engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine. Accordingly, there are provided methods of improving the fuel economy and/or piston cleanliness performance of an internal combustion engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine, comprising the step of providing or supplying to the engine and/or vehicle at least one of the lubricant compositions.

The invention will now be described with reference to the accompanying figures and examples, which are not limiting in nature, in which:

Figure 1 is a graph of coefficient of friction against time for various fully formulated blends in the high frequency reciprocating rig (HFRR) test showing the performance of blends containing an additive of formula (1) in comparison to a high performance commercially available blend as well as Baseline blends;

Figure 2 is a graph showing the change in kinematic viscosity (KV) at 100 °C and change in high shear (HTHS) viscosity for various fully formulated blends comprising either a dispersant viscosity modifier or a viscosity modifier upon the addition of an additive of formula (I);

Figure 3 is a graph showing the change in kinematic viscosity at 100 °C and change in high shear (HTHS) viscosity for various fully formulated blends comprising a dispersant viscosity modifier upon the addition of alternative additives of formula (I);

Figure 4 is a graph of coefficient of friction against temperature for various fully formulated blends in the high frequency reciprocating rig (HFRR) test showing the performance of blends containing an additive of formula (I) and/or ZDDP at different concentrations; and

Figures 5a to 5c are graphs of coefficient of friction against temperature for various fully formulated blends in the high frequency reciprocating rig (HFRR) test showing the performance of blends containing different additives of formula (I) (Figure 5a - magnesium stearoyl-2-lactylate (MgSL); Figure 5b - lithium stearoyl-2-lactylate (LiSL); and Figure 5c - molybdenum stearoyl-2-lactylate (MoSL)) and/or ZDDP at different concentrations. Examples

Example 1 - TEOST MHT-4 (ASTM D-7097)

A fully formulated baseline blend comprising commercially available Group III base stocks and a commercially available additive pack, anti-wear additive, 1.0 wt% of a viscosity modifier, 5.5 wt% of a dispersant viscosity modifier, pour point depressant, 0.4 wt% phenolic antioxidant, 0.3 wt% aminic antioxidant. The additive pack composition contained dispersant, magnesium sulphonate and phenate detergents, antioxidants and an anti-foaming agent. The Baseline blend has a known response in the TEOST MHT-4 test of approximately 85 mg of total deposits formation and therefore serves as a useful comparison for other tested blends.

Another fully formulated blend (“AO Blend”) was prepared which was identical in composition to the Baseline blend apart from 0.6 wt.% phenolic antioxidant and 0.5 wt.% aminic antioxidant was used and correspondingly less of the Group III base stocks used to make up the balance. This blend corresponds to a blend with a full treatment of mixed antioxidant of 1.1 wt.% formulated intended to improve deposit performance.

A blend according to the present invention (Blend 1) was prepared which was identical in composition to the Baseline blend apart from 0.4 wt% of sodium stearoyl-2- lactylate (NaSL) was added, the amount of additive pack was reduced by a minor amount to maintain similar concentrations relative to the base oil and correspondingly less of the Group Illbase stocks used to make up the balance.

Details of the blends tested and the results of the TEOST MHT-4 test in terms of total weight of deposits formed is provided in Table 3 below (amounts of components in the blends listed being weight percentages to one decimal place).

Table 3

As can be seen from the results in Table 3 above, the level of deposits is significantly reduced (from 85 mg to 68 mg) by increasing the amount of aminic and phenolic antioxidants in the blend (AO Blend) in comparison to the Baseline blend. An even greater reduction in deposits (from 85 mg to 65 mg) was also obtained instead by retaining the same level of antioxidant as in the Baseline blend but instead including an amount of an additive according to formula (I), namely NaSL.

The additive of formula (I) therefore has a comparable effect on reducing the level of deposits as observed for a large increase in the level of antioxidants in the blend. The additive of formula (I) could therefore represent a more cost effective means for increasing oxidative stability of the formulated oil in order to lower deposits in the TEOST MHT-4 test without recourse to large amounts of expensive antioxidant.

Example 2 - High Frequency Reciprocating Rig (HFRR) Test

Basic operating conditions of the HFRR for this testing are as follows:

i) 900 g load with steel ball (6mm diameter) and disk (10 mm diameter, 3 mm

thickness) as upper and lower test specimens, respectively;

ii) Operated with a frequency of 50 Hz, 1 mm stroke length and 1 s output interval; iii) Tested at 35°C, 65°C, 115°C, and 160°C in order of increasing temperature and for 10 minutes at each temperature, followed by 220°C for 20 minutes.

Further fully formulated blends were prepared for testing in the HFRR test, based on a 5W-30 baseline formulation. The HFRR test profile correlates well with the industry standard Sequence VID Fuel Economy Test. The HFRR test also represents a means for identifying friction modifiers by assessing the coefficient of friction of lubricating compositions including additives that may have that function.

Blends 2 and 3 according to the invention were prepared by adding 0.5 wt.% and 1.0 wt.%, respectively, of sodium stearoyl-2-lactylate (NaSL) to the 5W-30 baseline formulation. For comparison purposes, a high performance commercialized blend was also sourced for testing. Table 4 below provides information on the composition of the tested blends (amounts of components in the blends listed being weight percentages). The additive pack composition contained dispersant, sulphonate and phenate detergents, antioxidants, antiwear agents and an anti-foaming agent. Table 4

The performance of the high performance commercialized blend was verified by first testing the blend in the Sequence VID test (ASTM D7589). Table 5 below indicates the current 5W-30 and GF-5 Sequence VID limits and the corresponding results achieved for the high performance commercialized blend. As can be seen from the results in Table 5, the commercialized blend gives exceptional performance in the Sequence VID test and the results indicate that this blend would in fact pass at the current Sequence VID limits for a 0W-20 grade oil (%FEI SUM - 2.6 min; %FEI2 - 1.2min).

Table 5

The above Sequence VID test results for the high performance commercialized blend demonstrate that this blend represents a“high standard” for comparison purposes in the HFRR test. The prepared blends were evaluated in the HFRR test and the results are provided in the form of Figure 1, which is a graph of coefficient of friction versus time observed in the HFRR test. The stepwise nature of the results for each of the blends is characteristic of the stepwise temperature transitions of the HFRR test. The results shown in Figure 1 demonstrate that Blend 2 of the invention, containing 0.5 wt.% of NaSL, exhibits a good early response in the HFRR test (see, for instance, the response from approximately 1250 seconds to 1750 seconds) outperforming the 5W-30 Baseline blends, and exhibits comparable results to the 5W-30 Baseline blends during later stages of the test for remaining temperature transitions.

The results also demonstrate that Blend 3 of the invention, containing 1.0 wt.% of NaSL, has a noticeably lower coefficient of friction over the test period in comparison to the 5W-30 Baseline Blend. Blend 3 also outperforms the high performance commercialized blend over the majority of the temperature transitions of the test. These results indicate that an additive of formula (I) as described herein is able to effectively function as a friction modifier in a fully formulated oil.

Example 3 - PolyBLOCK Oxidation Test

Further fully formulated blends were prepared for testing in the PolyBLOCK Oxidation Test, a bulk oil oxidation test based on a 5W-30 baseline formulation. Table 6 below provides information on the composition of the tested blends (amounts of components in the blends listed being weight percentages) as well as the results of the bulk oil oxidation tests run to assess the potential to control sludge/deposits via a bulk oil oxidation test. Samples with good oxidative stability have smaller decreases in KV40. The bulk oil oxidation test was performed in a PolyBLOCK reactor system under the following conditions:

1. 80 g oil sample was placed in a 100 mL PolyBLOCK reactor before being heated to 170°C and held at this temperature with stirring at 500 rpm with a magnetic stirrer;

2. Once the reactor reached 170°C, 90 mL of 1% di-tert-butyl peroxide were added at 0.33 mL/min;

3. 19 hours after the reactor reached 170°C, oxygen began being added to the sample at 7.5 mL/min;

4. 48 hours after the reactor reached 170°C, the supply of oxygen was ceased and the reactor cooled to room temperature;

5. The kinematic viscosity at 40°C (KV 40) of the sample was measured before and after oxidation. Table 6

Results of the PolyBLOCK Oxidation Test shown above indicate that the additive of formula (I), sodium stearoyl-2-lactylate (NaSL), offers no improvement as well as no harms when compared to a comparative baseline blend.

Example 4 - Viscometric Profile Study

A viscometric study was performed to identify how the additive of formula (I), specifically sodium stearoyl-2-lactylate (NaSL), contributes to fuel economy, protects engine parts and meets OEM specifications. Further fully formulated blends were prepared for the viscometric study having the compositions set out in Table 7 below (amounts of components in the blends being weight percentages to one decimal place). Several different baseline blends were used containing different additive packages, including: i) a GF-4 conventional baseline blend containing a Group II base oil; ii) a GF-5 conventional baseline blend containing a combination of Group II and Group III base oils; iii) two synthetic GF-5 baseline blends containing Group III base oils; and iv) two conventional blends containing Group III base oils with different amounts of dispersants (3 wt.% or 6 wt.%). To each baseline blend was added varying amounts of a dispersant viscosity modifier (DVM), a viscosity modifier (VM) and pour point depressant (PPD). Varying amounts of additive of formula (I), sodium stearoyl-2-lactylate (NaSL), were also added to determine its impact on the performance of the blends. The DVM used in this instance was a multifunctional grafted polymer containing two groups of monomers grafted to a polyolefin backbone; one group of monomers imparting sludge dispersancy and the other group of monomers imparting soot handling properties. Specifically, the DVM used is the product of the reaction of maleic anhydride, acting as an acylating agent, with a polyolefmic backbone and subsequent reaction with: i) an ethylenically unsaturated hydrocarbyl monomer containing nitrogen in the presence of an initiator and ii) with a primary amine capable of reacting with free acyl groups.

Figure 2 shows the change in kinematic viscosity (KV) at 100 °C, as measured by ASTM D445, and change in viscosity under high temperature, high shear (HTHS) conditions, as measured by ASTM D4683, for a selection of the blends upon addition of NaSL. The dotted and dashed lines in Figure 2 give an indication of the error margins for the ASTM methods utilized in determining the above parameters.

The results of the viscometric study demonstrate that for the GF-4 conventional blends, the addition of NaSL (0.8 wt%) to a GF-4 blend in which the DVM is present leads to a substantial decrease in the KV at 100 °C, with little impact on HTHS viscosity. Reductions in KV correlate with improved fuel economy. However, reductions in KV are typically accompanied by corresponding reductions in HTHS viscosity. Higher HTHS viscosity indicates a better ability of the oil to protect and lubricate engine parts operating in this regime, such as the cam shaft. Therefore, reductions in HTHS are undesirable. The substantial lowering of KV value of the GF-4 conventional blend containing NaSL and DVM in combination with a retention of a similar HTHS viscosity value is particularly desirable, since this indicates that improvements in fuel economy may be achieved without loss in lubrication performance. This same change was also observed in the GF-5 conventional blends.

Table 7

In contrast, where no DVM is present, the addition of NaSL to the GF-4 and GF-5 conventional blends leads to no reduction of KV (see results for“GF-4 + NaSL” and“GF-5 + NaSL” blends). Where no DVM is included in the blends, the DVM is replaced with a VM bearing the same polymer backbone. The results in Figure 2 indicate that the addition of an additive of formula (I), NaSL (0.8 wt%), to a lubricating composition containing a VM, in place of a DVM, leads to no appreciable benefit in terms of modifying KV at 100 °C or HTHS viscosity. Moreover, no reduction in KV is observed as a result of the presence of the DVM in the absence of the additive of formula (I). This suggests that the reduction in KV, for little or no change in HTHS, is the result of a surprising synergy between the additive of formula (I) and the DVM in the lubricating composition. This synergy is also illustrated by the reduction of KV in the synthetic blends (“GF-5 syn (1)” and“GF-5 syn (2)” as well as the other conventional blends comprising different amounts of dispersant (“Con (3%)” and“Con (6%)”).

Example 5 - Viscometric Profile Study of Alternative Compounds of Formula 111

A further viscometric study was undertaken to investigate the benefit of the combination of alternative compounds of formula (I), in particular different metal stearoyl-2- lactylates (MSL), in the GF-4 conventional blends tested in Example 4. The GF-4 conventional blends tested had the same compositions as described in for Example 4, except that NaSL was replaced with the same amount (wt.%) of an alternative compound of formula (I), specifically molybdenum stearoyl-2-lactylate (MoSL) or titanium stearoyl-2-lactylate (TiSL). Figure 3 shows the results of the change in kinematic viscosity (KV) at 100 °C, as measured by ASTM D445, and change in viscosity under high temperature, high shear (HTHS) conditions, as measured by ASTM D4683, upon addition of for MoSL and TiSL. For comparison purposes, results for NaSL are also included in Figure 3, which demonstrates that alternative compounds of formula (I), in combination with DVM, achieve similar results in terms of KV reduction, for little or no change in HTHS as discussed above in connection with Example 4 and Figure 2.

Example 6 - High Frequency Reciprocating Rig (HFRRl Tests with blends also containing ZDDP

The HFRR test was again used as a means for determining the extent that an additive of formula (I) may perform as a friction modifier and also for assessing the impact of the presence of an anti-wear agent, namely ZDDP. Various fully formulated blends were prepared comprising 9.4 wt.% of a Zn-free additive pack; 7 wt.% of a viscosity modifier; varying amounts of sodium stearoyl-2-lactylate (NaSL) (0 (=“Baseline”), 0.25, 0.5 or 0.75 wt.%), varying amounts of ZDDP (0 ppm or 400 ppm, on an elemental phosphorus basis); and a balance of group III base stock.

The various blends were evaluated in the HFRR test using the following conditions. i) 400 g load with steel ball (6mm diameter) and disk (10 mm diameter, 3 mm thickness) as upper and lower test specimens, respectively;

ii) Operated with a frequency of 40 Hz, 1 mm stroke length and 5 s output interval;

iii) Tested at 40°C for 10 minutes and 60°C, 80°C, 100°C, 120°C, and 140°C in order of increasing temperature for 5 minutes each.

The test results are provided in Figure 4, which shows the change in coefficient of friction in response to change of temperature during the test. The results in Figure 4 show a general trend of lowering of the coefficient of friction as the content of NaSL in the tested blend increases from 0 wt.% to 0.75 wt.%. A comparison of the Baseline blends comprising no NaSL and either 0 or 400 ppm ZDDP (on an elemental phosphorus basis) indicates that the presence of ZDDP also lowers the coefficient of friction. Surprisingly, however, the results in Figure 4 also demonstrate that the reduction in the coefficient of friction resulting from the presence of ZDDP is also at least additive with the reduction in the coefficient of friction resulting from the presence of NaSL. This suggests that the additive of formula (I) provides friction modifying effects through a different mechanism than ZDDP. The combination of ZDDP and NaSL in the fully formulated oil is therefore capable of providing a substantial improvement in performance in the HFRR Tests.

Example 7 - High Frequency Reciprocating Rig (HFRR) Tests with blends containing other additives of formula (II in combination with ZDDP

The HFRR test was used as a means for verifying that different additives of formula (I) may also act as friction modifiers and assessing the effect of the presence of an anti-wear additive, namely ZDDP.

Example 6 was repeated with blends containing varying amounts of different additives of formula (I), namely magnesium stearoyl-2-lactylate (MgSL), lithium stearoyl-2- lactylate (LiSL) or molybdenum stearoyl-2-lactylate (MoSL) (0 (=“Baseline”), 0.25, 0.5 or 0.75 wt.%) instead of sodium stearoyl-2-lactylate (NaSL), together with ZDDP (400 ppm, on an elemental phosphorus basis). The various blends were evaluated in the HFRR test substantially as described in Example 6 and the results are provided in Figure 5a (MgSL), Figure 5b (LiSL) and Figure 5c (MoSL), which show the change in coefficient of friction in response to change of temperature during the tests. The results in Figures 5a to 5c further demonstrate the benefits of the combination of ZDDP and other additives of formula (I) in reducing the coefficient of friction in the HFRR test.

The results in Figure 5a to 5c generally illustrate the same trend observed for NaSL- and ZDDP-containing blends in Example 6. In each case, the extent the coefficient of friction is lowered from that achieved with the Baseline blend is enhanced by increasing the concentration of the additive of formula (I) in the blend, thereby providing further

verification of the benefits of an additive of formula (I) as a friction modifier. Furthermore, the combination of ZDDP and the additive of formula (I) gives better performance in the HFRR test than ZDDP alone.

Example 8 - Sequence IVA Engine Wear Tests

Sequence IVA engine tests according to ASTM test method ASTM D6891 were undertaken for fully formulated blends based on a 5W-30 baseline formulation. The Sequence IVA test is an industry standard test used to evaluate the camshaft wear protection of internal combustion engine lubricating compositions. The 5W-30 baseline blend was tested alongside a blend also containing an additive of formula (I), molybdenum stearoyl-2- lactylate (MoSL) (“Blend 4”). Table 8 below provides information on the composition of the tested blends (amounts of components in the blends listed being weight percentages to one decimal place).

Table 8

The results in Table 8 indicate a significant reduction in average camshaft wear in the Sequence IVA test for Blend 4 comprising MoSL in comparison to the 5W-30 baseline blend. These results demonstrate the anti-wear benefits of the compositions of the invention.

Example 9 - Sequence IIIH Engine Wear Tests

Sequence IIIH engine tests according to ASTM test method ASTM D8111 were undertaken for fully formulated blends based on a 5W-30 baseline formulation. The Sequence IIIH test is an industry standard test used to evaluate protection against oil thickening and piston deposits by internal combustion engine lubricating compositions.

The 5W-30 baseline blend was tested alongside a blend also containing sodium stearoyl-2-lactylate (NaSL) (“Blend 5”). Table 9 below provides information on the composition of the tested blends (amounts of components in the blends listed being weight percentages to one decimal place).

Table 9

The results in Table 9 indicate a significant improvement in weighted piston deposit (WPD) merits in the Sequence IIIH test for Blend 5 in comparison to the 5W-30 baseline blend. These results demonstrate the piston cleanliness performance benefits of lubricant compositions of the invention. The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm.”

Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope and spirit of this invention.