JP2008519127A - Multi-functional lubricant additive package - Google Patents

Abstract

The present invention provides a multifunctional lubricant additive package or composition that improves lubricant load capacity, scuffing (scoring) resistance, and other performance characteristics. The composition includes a molybdenum compound, a secondary zinc dithiophosphate compound, an aryl or alkyl phosphate ester compound, and a compound having an alkylthiocarbamoyl group. The present invention further provides a method for improving the performance characteristics of a lubricant. The method includes mixing a lubricant base oil or a fully formulated lubricant with the multifunctional lubricant additive composition.

Description

  The present invention relates to a multifunctional lubricant additive composition or package that improves the performance characteristics of a lubricant. More specifically, the present invention provides a lubricant with superior performance characteristics such as improved load capacity, improved scuffing resistance, reduced friction, and extended surface fatigue life. Functional lubricant additive composition or package.

  This application claims the benefit of US Provisional Application No. 60 / 625,416, filed on Nov. 4, 2004, and is owned by the owner of this application and is a co-pending subsequent application (which is filed with this application). And incorporated herein by reference in its entirety): "Lubricants Additive Packages for Improving Load-Carrying Capacity and Surface Fatigue Life (lubricants that improve load capacity and surface fatigue life)" (Attorney Docket No. 0002290 WOU, EH-11605), “Lubricants Containing Multi-Functional Additive Packages T erein for Improving Load-Carrying Capacity, Incrementing Surface Fatigue Life and Reducing Friction (Lubricant containing a multi-functional additive package that increases load capacity, extends surface fatigue life, and reduces friction et al. , EH-11697), and "Multifunctional Additive Package for a Rough Mechanical Component Surface" (Attorney Doe 16 No2 8). This invention was made under a contract with the National Institute of Standards and Technology of the US Government under Contract Number: 70NANB0H3048.

  Manual or automatic transmissions; mechanical systems such as single-stage and multi-stage aircraft transmissions (but not limited to those used to propel rotorcraft, used to change the rotational speed of sections in gas turbine engines) (Including push belt continuously variable transmissions; and traction drive continuously variable transmissions) have a wide contact surface. These contact portions or zones (e.g., drive rotating surfaces), gears, and ball-roller bearings are known to be susceptible to large surface pressures. In addition, internal combustion engines and other propulsion devices, especially those that have become popular for high performance and racing applications, are subject to heavy loads in the form of inertial loads, large slip and rotational speeds, and marginal lubrication. Imposes a demand to become. In addition, many recently developed transmission systems that are designed to be smaller or lighter to maximize transmission throughput will reduce frictional resistance and fatigue within the larger contact zone of the mechanical system. There is an increasing demand.

  To meet the demands of these harsh applications, lubricants (especially those with special additives) play an essential role in preventing and minimizing surface wear and scuffing (scoring). . Lubricants generally reduce the accumulation of significant damage in lubricated parts caused by surface fatigue and overload.

  Examples of known lubricants are described in the following publications (these publications are incorporated herein by reference in their entirety): Phillips, W .; D. Ashless phosphorous-containing lubrication oil additive; Lubricant Additives Chemistry and Application (chemistry and application of ash-free phosphorus-containing lubricant oil; Lubricant additive chemistry and application) 45-111 (L.R.c. ); And Kenbeck, D .; , And T. F. Buenemann, Organic Modifiers; Lubricant Additives Chemistry and Application (organic modifiers; lubricant additive chemistry and applications) 203-222 (LR Rudick, Marcel Dekker, Inc. 2003).

  In order to increase the overall power efficiency of mechanical systems, recently developed system optimization techniques strongly suggest the need for new lubricant additives with better performance. By reducing friction, wear, and pressure and improving scoring resistance, these additives extend the surface fatigue life of lubricated contact surfaces in transmission systems and propulsion devices.

  The present invention provides a lubricant additive that improves performance characteristics such as load capacity of a mechanical system. Mixing the additive composition provided by the present invention with a lubricant raw material and optionally other additives provides many performance benefits, such as reduced friction, wear and scuffing. Having a fully formulated lubricant.

  The present invention provides a lubricant additive comprising elements or components intended to improve the performance characteristics of a lubricant base oil, or wear resistance (AW), extreme pressure (EP), friction regulation (FM) and surface fatigue. A fully formulated lubricant is provided that includes a lifetime (SFL) modifying composition.

  In a preferred embodiment, the present invention provides a multifunctional lubricant additive composition that improves the performance characteristics of natural or synthetic lubricants for use in transmission fluid products that meet both civil and military standards. To do.

  In other embodiments, the present invention provides multifunctional compositions used to improve the performance of metals or alloys in power transmission components (including gears, bearings, splines, shafts and springs).

  In other embodiments, the present invention relates to automobiles (both general vehicles (products) and special vehicles (eg, for racing and other high performance)), and on-road and off-road heavy equipment (eg, farm equipment and construction). A multifunctional lubricant additive composition is provided that improves the performance characteristics of the engine and associated propulsion device used to power the machine.

  In other embodiments, the present invention beneficially reduces friction and scuffing (scoring) and surface degradation due to fatigue (but not limited to micropitting, macropitting, and wear). In order to produce a fully formulated lubricant that improves the resistance to the present invention, and a multifunctional lubricant additive composition that can be mixed with lubricant ingredients and other additives.

In yet another embodiment, the present invention provides a multifunctional lubricant additive composition that improves the performance characteristics of the lubricant, the composition comprising one or more of the following components:
(A) Molybdenum compounds represented by the following general formula:

[Wherein, X ¹ is an oxygen or sulfur atom, R ³ and R ⁴ are each independently a C _n H _{2n + 1} alkyl group, and n is an integer of about 2 ≦ n ≦ 10. , M is an integer of about 0 ≦ m ≦ 4];
(B) a secondary zinc dithiophosphate compound represented by the following general formula:

[Wherein R ³ , R ⁴ , R ⁵ and R ⁶ are each represented by the following formula:

A C _h H _{2h + 1} secondary alkyl group represented by:
h is an integer of about 3 ≦ h ≦ 11, R ⁷ and R ⁸ are each a C _i H _{2i + 1} alkyl group, and i is an integer of about 1 ≦ i ≦ 5];
(C) Aryl or alkyl phosphite compounds represented by the following general formula:

[Wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are each a C _j H _{2j + 1} alkyl group, and j is an integer of about 1 ≦ j ≦ 20. The alkyl group exhibits a tertiary structure]; and (d) a compound represented by the following general formula having at least one alkylthiocarbamoyl group:

[Wherein, R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each a C _k H _{2k + 1} alkyl group, k is an integer of about 1 ≦ k ≦ 30, and R ¹⁵ , R ¹⁶ , R ^17, and R ^18, optionally together with the nitrogen atom to which they are attached to form a ring structure; (a) is a chain of sulfur atoms, S _n, or S- (CH _{2) m} - S, n is an integer of about 1 ≦ n ≦ 10, m is an integer of about 1 ≦ m ≦ 6]; the total amount of compounds (a) to (d) is the total amount of lubricant About 15 mol% or less.

  The present invention provides a multifunctional lubricant additive composition that improves the performance characteristics of a lubricant base oil or a fully formulated lubricant. Preferably, the composition comprises the following components as described below: (I) a molybdenum compound (a) at a concentration of about 0.1 to 6 mol% relative to the total amount of lubricant; Dialkyl (secondary) zinc dithiophosphate compound (b) at a concentration of about 0.1-6 mol% relative to the total amount; (III) at a concentration of about 0.1-6 mol% relative to the total amount of lubricant 4 additions in the composition comprising: an aryl or alkyl phosphite compound (c); (IV) an alkylthiocarbamoyl compound (d) at a concentration of about 0.1-6 mol% relative to the total amount of lubricant The total concentration of agent will not exceed about 15 mole percent based on the total amount of lubricant.

The multifunctional lubricant additive composition has the following components:
(A) Molybdenum compounds represented by the following general formula:

Wherein X ¹ is an oxygen or sulfur atom, R ³ and R ⁴ are each independently a C _n H _{2n + 1} alkyl group, and n is about 2 ≦ n ≦ 10, preferably An integer of about 4 ≦ n ≦ 6, and m is an integer of about 0 ≦ m ≦ 4];
(B) Secondary dithiophosphate zinc compound (or dialkyldithiophosphate zinc compound) represented by the following general formula:

[Wherein R ³ , R ⁴ , R ⁵ and R ⁶ are each represented by the following formula:

A C _h H _{2h + 1} secondary alkyl group represented by:
h is an integer of about 3 ≦ h ≦ 11, preferably about 4 ≦ h ≦ 6, R ⁷ and R ⁸ are each a C _i H _{2i + 1} alkyl group, and i is about 1 ≦ i ≦ 5, preferably an integer of about 1 ≦ i ≦ 3];
(C) Aryl or alkyl phosphite compounds represented by the following general formula:

[Wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are each a C _j H _{2j + 1} alkyl group, and j is about 1 ≦ j ≦ 20, An integer of about 4 ≦ j ≦ 8 and the alkyl group exhibits a tertiary structure];
(D) a compound represented by the following general formula having at least one alkylthiocarbamoyl group:

[Wherein R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ are each a C _k H _{2k + 1} alkyl group, and k is about 1 ≦ k ≦ 30, preferably about 4 ≦ k ≦ 8. an ^{integer, R 15, R 16, R} 17, and R ^18, optionally together with the nitrogen atom to which they are attached to form a ring structure; (a) is a chain of sulfur atoms, S _n Or S— (CH ₂ ) _m —S, n is an integer of about 1 ≦ n ≦ 10, preferably about 1 ≦ n ≦ 6, and m is about 1 ≦ m ≦ 6, preferably , An integer of about 1 ≦ m ≦ 3];
The total amount of the compounds (a) to (d) is about 15 mol% or less based on the total amount of the lubricant.

  Compound (a) of the multifunctional lubricant additive composition is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant. In a preferred embodiment, compound (a) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.

  Compound (b) of the multifunctional lubricant additive composition is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant. In a preferred embodiment, compound (b) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.

  Compound (c) of the multifunctional lubricant additive composition is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant. In a preferred embodiment, compound (c) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.

  Compound (d) of the multifunctional lubricant additive composition is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant. In a preferred embodiment, compound (d) is present in an amount of about 0.1-3 mol% relative to the total amount of lubricant.

  Lubricants that can be improved by the present invention include, but are not limited to, gear oil, bearing oil, sliding surface lubricating oil, chain lubricating oil, and engine oil. In a preferred embodiment, various types of lubricants, greases, especially synthetic polyol ester (POE) based lubricants can be used as the lubricating base oil.

  The present invention is useful as an additive composition for aircraft (aerospace) and automotive natural and synthetic lubricants. Furthermore, the combination of the multifunctional additive composition of the present invention and the lubricant improves transmission power efficiency and system power density.

  Specific applications also include turbine engine oil and transmission oil designed to meet government civil (FAA) and military (DoD) standards and requirements. Further uses of these multifunctional additive compositions include scuffing of metals and alloys commonly used in power transmission components, including but not limited to gears, bearings, splines, shafts, and springs. Has a proven ability to improve (scoring) properties. Thus, such improvements reduce component and system failures, as well as failures in the customer acceptance test protocol (ATP). The additive composition also improves pitting (surface) fatigue life and reduces the rate of component and system degradation due to wear and other phenomena.

In another embodiment, the present invention provides a method for improving the performance characteristics of a lubricant. This method
A lubricant fully mixed by mixing a lubricant and a multifunctional lubricant additive composition comprising at least one of components (a) to (d) of the multifunctional lubricant additive composition. Including the steps of: In this embodiment, when the total amount of the four additives is about 15 mol% or less based on the total amount of the lubricant, the molar concentrations of the compounds (a) to (d) are changed to achieve the desired effect. Can be done.

  The following formulations and experimental results illustrate some non-limiting embodiments of the multifunctional additive composition of the present invention.

Formulation # 4
In this embodiment, the multi-function additive package was added to Hatco HXL-7994 oil to make Formulation # 4. Hatco HXL-7994 oil is specially made by Hatco to replicate Exxon-Mobil Jet Oil II, but without the tricresyl phosphate (TCP), an anti-wear additive of Exxon-Mobil Jet Oil II. Prepared. Hatco HXL-7994 oil contains an antioxidant package and a yellow corrosion inhibitor, and uses a 5 cSt polyol ester base oil (HXL-1570 having the properties described in Table 1 below).

  Formulation # 4 contained the following additives.

  This multifunctional additive package of Formulation # 4 increased the load capacity of Hatco-HXL-7994 oil by about 3.94 times, compared to other brands and versions of MIL-PRF-23699 oil It is superior to conventional oils such as Exxon-Mobile Jet Oil II (MIL-PRF-23699 standard, 5 cSt gas turbine engine oil), which usually has excellent lubricating performance. As can be seen from the drawing, the Hatco-HXL-7994 oil (10) has a scuffing (scoring) mean failure load stage (arrow 11) of about 5.7 and the Exxon-Mobile Jet Oil II (20) of about 19.2 scuffing (scoring) average failure load stage (arrow 21) and formulation # 4 (30) has about 22.5 scuffing (scoring) average failure load stage (arrow 31). This indicated that the loading capacity of Formulation # 4 was about 3.94 times greater than Hatco-HXL-7994 oil.

Experimental Results Wedeven Associates, Inc. Using a modified version of the commonly accepted WAM load capacity test method ("WAM test"), Formulation # 4 of the present invention and two reference oils (Hatco-HXL-7994 oil and Exxon-Mobile Jet Oil II) ) Experimental results were obtained. The WAM test is designed to evaluate the load capacity of a lubricant and the load bearing surface by assessing the wear, tear and scuffing (scoring) of the bearing surface over a wide temperature range. .

  Table 3 below lists the WAM test conditions used to test various lubricants of the present invention.

  For a detailed description of the WAM test, see WAM High Speed Load Capacity Test Method (WAM Fast Load Capacity Test Method), SAE Aerospace AIR 4978, Revision B, 2002, and Wedeven US Pat. No. 5,679,883. Incorporated herein by reference in its entirety).

  For high load oil, the test is often stopped at the load stage 30 without the phenomenon of scuffing (scoring). Tests can be conducted with a modified test protocol to identify candidate formulations that will be suspended. The modified test protocol is performed at an entraining velocity that is smaller than the standard test protocol, thereby reducing EHD film thickness and producing greater asperity interaction. The test is essentially performed by reducing the ratio of membrane pressure to surface roughness (h / σ).

  This modified test protocol was developed for heavy duty oils used in aircraft (aerospace) gearboxes. These oils include DOD-PRF-85734 oil for the US Navy, and Def Stan 91-100 oil for the UK Department of Defense. According to a modified test protocol, the maximum load oil currently used in military aircraft causes scuffing (scoring) failure at load stages in the range of about 19 to 28.

AISI 9310 sample preparation:
Formulation # 4, Hatco HXL-7944 oil, and Exxon-Mobil Jet Oil II were comparatively evaluated for scuffing (scoring) resistance using a load capacity test method developed for the US Navy. In this test method, ball and disk samples were used. The diameter of the ball sample was 13/16 inch, the diameter of the disk sample was 4 inches, and the thickness was 1/2 inch. Material composition, hardness and surface finish were closely controlled. Samples were made from AISI 9310 steel, a surface carburized alloy that is very common for gear applications.

  AISI 9310 balls, or “Hard Ground” balls, were heat treated and polished in the ball manufacturing process. These balls were made through a hard polishing process. Surface finish after this work step resulted in between about 10-12 microinches Ra.

  Sample composition, hardness and surface finish are listed below.

Scuffing (scoring) results:
Scuffing (scoring) results for Formulation # 4, Hatco HXL-7944 oil and the reference oil Exxon-MobilJet Oil II are summarized in Table 5 and shown in the drawing.

  The load capacity is indicated by the scuffing (scoring) average defect stage (load stage). The improvement in performance is recognized by the higher load stage. As shown in Table 5, the experimental results show that the scuffing (scoring) average failure stage for formulation # 4 is about 22.5. The scuffing (scoring) load is 3.94 times greater than the Hatco HXL-7944 oil with a scuffing (scoring) average failure stage of 5.7. Furthermore, the load capacity of Formulation # 4 is superior to Exxon-Mobil Jet Oil II with a scuffing (scoring) average failure stage of 19.2.

  Although the above-described embodiments are directed to polyol ester (POE) type lubricants, those skilled in the art will recognize that the compositions of the present invention may be used in other lubricant raw material compositions (grease, mineral oil (hydrocarbon), polyalkylene). Including, but not limited to, lubricants including glycol (PAG), aromatic naphthalene (AN), alkylbenzene (AB), and polyalphaolefin (PAO) types. I will admit.

  Accordingly, it should be understood that the foregoing description is only illustrative of the invention. Those skilled in the art can implement various alternatives and modifications without departing from the invention. The present invention includes such alternatives, modifications and variations, which are within the scope of the appended claims.

FIG. 6 is a diagram illustrating the relationship between average traction coefficient and average load stage for various lubricants. The vertical arrows 11, 21, 31 are average load stages (load capacities) that result in scuffing (scoring) defects in Hatco HXL-7944 oil (10), Exxon-Mobile Jet Oil II (20) and Formulation # 4 (30). ) Respectively. A larger scuffing (scoring) load stage indicates a greater lubricant load capacity.

Claims (24)

(A) Molybdenum compounds of the following general formula:

[Wherein, X ¹ is an oxygen or sulfur atom, R ³ and R ⁴ are each independently a C _n H _{2n + 1} alkyl group, and n is an integer of about 2 ≦ n ≦ 10. , M is an integer of about 0 ≦ m ≦ 4];
(B) a secondary zinc dithiophosphate compound of the general formula:

[Wherein R ³ , R ⁴ , R ⁵ and R ⁶ are each represented by the following formula:

A C _h H _{2h + 1} secondary alkyl group of
h is an integer of about 3 ≦ h ≦ 11, R ⁷ and R ⁸ are each a C _i H _{2i + 1} alkyl group, and i is an integer of about 1 ≦ i ≦ 5];
(C) aryl or alkyl phosphite compounds of the general formula:

[Wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are each a C _j H _{2j + 1} alkyl group, and j is an integer of about 1 ≦ j ≦ 20. The alkyl group exhibits a tertiary structure]; and (d) a compound of the following general formula having at least one alkylthiocarbamoyl group:

[Wherein, R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each a C _k H _{2k + 1} alkyl group, k is an integer of about 1 ≦ k ≦ 30, and R ¹⁵ , R ¹⁶ , R ^17, and R ^18, optionally together with the nitrogen atom to which they are attached to form a ring structure; (a) is a chain of sulfur atoms, S _n, or S- (CH _{2) m} - S, n is an integer of about 1 ≦ n ≦ 10, and m is an integer of about 1 ≦ m ≦ 6];
And the total amount of the compounds (a) to (d) is about 15 mol% or less based on the total amount of the lubricant.   The composition of claim 1 wherein compound (a) is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant.   The composition of claim 1, wherein compound (a) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   The composition of claim 1 wherein compound (b) is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant.   The composition of claim 1, wherein compound (b) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   The composition of claim 1, wherein compound (c) is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant.   The composition of claim 1 wherein compound (c) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   The composition of claim 1, wherein compound (d) is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant.   The composition of claim 1, wherein compound (d) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   The composition according to claim 1, wherein the lubricant is selected from the group consisting of gear oil, bearing oil, sliding surface lubricating oil, chain lubricating oil, and engine oil. A lubricant,
(A) Compounds represented by the following general formula:

Wherein X ¹ is an oxygen or sulfur atom, R ³ and R ⁴ are each a C _n H _{2n + 1} alkyl group, n is an integer of about 2 ≦ n ≦ 10, m Is an integer of about 0 ≦ m ≦ 4];
(B) Compounds represented by the following general formula:

[Wherein R ³ , R ⁴ , R ⁵ and R ⁶ are each represented by the following formula:

A C _h H _{2h + 1} secondary alkyl group represented by:
h is an integer of about 3 ≦ h ≦ 11, R ⁷ and R ⁸ are each a C _i H _{2i + 1} alkyl group, and i is an integer of about 1 ≦ i ≦ 5];
(C) Compounds represented by the following general formula:

[Wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are each a C _j H _{2j + 1} alkyl group, and j is an integer of about 1 ≦ j ≦ 20. The alkyl group exhibits a tertiary structure]; and (d) a compound represented by the general formula:

[Wherein, R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each a C _k H _{2k + 1} alkyl group, k is an integer of about 1 ≦ k ≦ 30, and R ¹⁵ , R ¹⁶ , R ^17, and R ^18, optionally together with the nitrogen atom to which they are attached to form a ring structure; (a) is a chain of sulfur atoms, S _n, or S- (CH _{2) m} - S, n is an integer of about 1 ≦ n ≦ 10, and m is an integer of about 1 ≦ m ≦ 6];
A multifunctional lubricant additive composition, wherein the total amount of the compounds of (a) to (d) is about 15 mol% or less based on the total amount of the lubricant;
A method for improving the performance characteristics of a lubricant, comprising the step of:   12. A method according to claim 11, wherein compound (a) is present in an amount of about 0.1 to 6 mol%, based on the total amount of lubricant.   12. The method of claim 11, wherein compound (a) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   12. A method according to claim 11, wherein compound (b) is present in an amount of about 0.1 to 6 mol%, based on the total amount of lubricant.   12. The method of claim 11, wherein compound (b) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   12. The method of claim 11, wherein compound (c) is present in an amount of about 0.1 to 6 mole percent, based on the total amount of lubricant.   12. The method of claim 11, wherein compound (c) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   12. A method according to claim 11, wherein compound (d) is present in an amount of about 0.1 to 6 mol%, based on the total amount of lubricant.   12. The method of claim 11, wherein compound (d) is present in an amount of about 0.1 to 3 mole percent, based on the total amount of lubricant.   12. The method of claim 11, wherein the lubricant is selected from the group consisting of gear oil, bearing oil, sliding surface lubricating oil, chain lubricating oil, and engine oil. A base lubricant,
At least one additive selected from the group consisting of molybdenum compounds, secondary zinc dithiophosphate compounds, aryl or alkyl phosphite compounds, and compounds having at least one alkylthiocarbamoyl group;
Including
(A) The molybdenum compound has the following general formula:

[Wherein, X ¹ is an oxygen or sulfur atom, R ³ and R ⁴ are each independently a C _n H _{2n + 1} alkyl group, and n is an integer of about 2 ≦ n ≦ 10. , M is an integer of about 0 ≦ m ≦ 4];
(B) the secondary zinc dithiophosphate compound has the following general formula:

[Wherein R ³ , R ⁴ , R ⁵ and R ⁶ are each represented by the following formula:

A C _h H _{2h + 1} secondary alkyl group of
h is an integer of about 3 ≦ h ≦ 11, R ⁷ and R ⁸ are each a C _i H _{2i + 1} alkyl group, and i is an integer of about 1 ≦ i ≦ 5] And
(C) the aryl or alkyl phosphite compound has the general formula:

[Wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are each a C _j H _{2j + 1} alkyl group, and j is an integer of about 1 ≦ j ≦ 20. The alkyl group exhibits a tertiary structure];
(D) The compound having at least one alkylthiocarbamoyl group has the following general formula:

[Wherein, R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each a C _k H _{2k + 1} alkyl group, k is an integer of about 1 ≦ k ≦ 30, and R ¹⁵ , R ¹⁶ , R ^17, and R ^18, optionally together with the nitrogen atom to which they are attached to form a ring structure; (a) is a chain of sulfur atoms, S _n, or S- (CH _{2) m} - S, n is an integer of about 1 ≦ n ≦ 10, and m is an integer of about 1 ≦ m ≦ 6];
A multifunctional lubricant, wherein the total amount of the compounds (a) to (d) is about 15 mol% or less based on the total amount of the lubricant.   The multifunctional lubricant additive composition according to claim 1, wherein the molar ratio of the component compounds (a), (b), (c) and (d) is about 1: 1: 1: 1. object.   The multifunctional lubricant additive composition according to claim 1, wherein the molar ratio of the component compounds (a) and (b) is about 1: 1.   The multifunctional lubricant additive composition according to claim 1, wherein the molar ratio of the component compounds (a), (b), (c) and (d) is about 10: 10: 5: 1. object.

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