JP2003523454A - Lubricating oil composition containing trinuclear compound antioxidant - Google Patents

Abstract

(57) SUMMARY The present invention relates to a Group I base stock and a general formula (I): Mo ₃ S _x- (Q), wherein x is 4-10, Q is a core group, and A lubricating oil composition containing an oil-soluble trinuclear organomolybdenum compound having a kinematic viscosity (KV ₁₀₀ ) at 100 ° C. of about 2 × 10 ⁻⁶ m ² / sec. 50 × 10 ⁻⁶ m ² / sec (2 cSt to 50 cSt), saturate content <90% w / w, aromatic content> 10% w / w and sulfur content> 0.03% w / w And the composition. The compositions have improved stability when compared to Group II, III or IV basestocks containing the same antioxidants or Group I basestocks containing dinuclear dithiocarbamate molybdate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a lubricating oil composition having a relatively small amount of saturated hydrocarbons having a natural oxidation stability and a large amount of sulfur, and particularly to a lubricant used in an internal combustion engine.

BACKGROUND OF THE INVENTION

The lubricating oil composition is used for smooth operation of internal combustion engines, power transmission parts including automatic transmissions, shock absorbers, power steering devices and gears. The engine oil of an internal combustion engine, in particular, (i) lubricates the various sliding interfaces, such as between the piston ring and the cylinder liner, in the bearings of the crankshaft and connecting rod, and in the valve drive mechanism, including cams and valve lifters. ii) Cool the engine, (i
ii) functions to cleanly disperse combustion products and (iv) prevent corrosion and prevent rust.
The recent urgent demand for high performance engines means that the demands from the lubricants used in such engines have increased. Lubricating oils used in such engines are usually oxidized by oxygen and / or nitrogen oxides (NOx) contained in blow-by gas (ie, gas that leaks from the combustion chamber gas to the crankcase at the piston / cylinder interface). Deteriorates due to. The higher the engine performance requirements, the higher the NOx concentration in the blow-by gas. The detrimental effects of oxidation can be and have been mitigated by using various additives, including antioxidants, and by using base stocks that are relatively stable to oxidation.

The control of the oxidation process is relatively high in saturated hydrocarbons (hereinafter “saturates”) than Group I basestocks, which are relatively low in saturated hydrocarbons because Group I base oils have a relatively high tendency to oxidize II It has been improved to some extent by the use of lubricating oil compositions containing Group III, III or IV basestocks. Group II, Group III and I
Group V basestocks are typically more expensive than conventional Group I basestocks. In order to expand the use of Group I basestocks for future engine oil products, it is important to identify suitable additives to enhance their properties. A feature of the invention is to improve the oxidative stability of Group I base stocks.

[0003]

[Details of the invention]

Here, it is possible to obtain the desired degree of oxidative stability from Group I base oils by carefully selecting the antioxidants without resorting to the relatively expensive Group II, Group III and / or Group IV basestocks. I knew it was. Accordingly, the present invention is a lubricating oil composition comprising a large amount of Group I base stock and the following general formula: Mo ₃ S _x- (Q) (I), where x is from 4 to 10, preferably 7. And Q is a core group, which may be a ligand.), Wherein the composition comprises an antioxidant containing an oil-soluble trinuclear organomolybdenum compound.

The lubricating oil composition of the present invention contains a large amount of Group I base stock as defined in API 1509. Thus, e.g., I Group basestocks, KV ₁₀₀ is ^{2 × 10 - 6 ~50 × 10} -6 m 2 / sec (2~50 cSt), viscosity index of 80 to 120, a saturates content of <90% w /
It may be mineral oil or a blend thereof with w, aromatic content> 10% w / w and sulfur content> 0.03% w / w (300 ppm). Group I basestocks are obtained by solvent extraction followed by dewaxing. Specific examples of Group I base stocks include MCT 30
(VI 94, saturates 78% w / w, sulfur 0.28% w / w). Dewaxed, for example, hydrocracked distillate or raffinate by conventional or catalytic dewaxing processes, has a sulfur content of 0.03% w / w and an aromatic content of <10% w / w Group II or III. Base stock, eg RLOP 500R (VI 106, saturates> 97% w / w), or Mobil Jurong 500N
(VI 99, saturates> 97% w / w). Poly-α-olefins are Group IV basestocks. According to an embodiment, the invention further provides that the kinematic viscosity at 100 ° C. (KV ₁₀₀ ) is about 2 × 1.
0 ^-6 to 50 x 10 ^-6 m ² / sec (2 cSt to 50 cSt), saturate content of at least 90% w / w, aromatic content> 10% w / w and sulfur content> 0.03% w A method of improving the oxidative stability of a lubricating oil composition comprising a Group I basestock having a / w (300 ppm), said basestock having the following general formula: Mo ₃ S _x- (Q) (I (In the formula, x is 4 to 10, preferably 7, Q is a core group and may be a ligand.) Effectiveness of an antioxidant containing an oil-soluble trinuclear organomolybdenum compound having The method comprises the step of adding an amount.

The trinuclear molybdenum compound has the following formula (I) Mo ₃ S _x- (Q) (I) (wherein x is 4 to 10, preferably 7, and Q is a core group). . Trinuclear molybdenum compounds are relatively new and have been described in our previous US Patent Application No. 5,906,968. The disclosure of this prior U.S. patent regarding the structure, process and properties of the trinuclear molybdenum compounds is hereby incorporated by reference. In these compounds, the core group (Q) is a ligand that can make the organomolybdenum compound of formula (I) oil-soluble and ensure that the charge of said molybdenum compound is substantially neutral. May be. The core group (Q) is generally L _y
(Where L is a ligand and y has a sufficient number, type and charge to render the compound of formula (I) oil-soluble and to neutralize the charge of the compound of formula (I) as a whole. ) Associated with a suitable ligand. Therefore, more specifically, the trinuclear molybdenum compound used in the composition of the present invention may be represented by the formula (II): Mo ₃ S _x L _y (II).

The ligand “L” is suitably a dihydrocarbyl dithiocarbamate of the structure (—S ₂ CNR ₂ ), where the dihydrocarbyl group, R ₂ imparts oil solubility to the molybdenum compound. In this case, the term "hydrocarbyl" means a substituent having a carbon atom directly attached to the rest of the ligand and is primarily hydrocarbyl of a nature within the scope of this invention. Such substituents include the following substituents.
(1) Hydrocarbon substituents, ie aliphatic substituents (eg alkyl or alkenyl)
, Alicyclic substituents (eg, cycloalkyl or cycloalkenyl), aromatic substitutions, aliphatic substitutions, alicyclic substituted aromatic rings, etc., or cyclic substituents whose rings are completed through other moieties of other ligands (I.e., the two indicated substituents can together form an alicyclic group); (2) substituted hydrocarbon substituents, i.e., do not alter the properties of the predominant hydrocarbyl group with which the invention is concerned. A substituent containing a non-hydrocarbon group. Those skilled in the art will appreciate that suitable groups (e.g., halo (especially chloro), amino, alkoxyl, mercapto, alkylmercapto, nitro, nitroso, sulfoxy, etc.); and (3) heterosubstituents, i. Substituents which are hydrocarbons of the nature of, but which contain atoms other than carbon present in the chain or ring composed of carbon atoms.

The hydrocarbyl group is preferably an alkyl group (eg, the carbon atom attached to the rest of the ligand “L” is a primary, secondary or tertiary carbon atom), an aryl group, a substituted aryl group and / or It is an ether group. Importantly, the hydrocarbyl group of the ligand must have a sufficient number of carbon atoms to make compound (I) soluble or dispersible in the oil to which the trinuclear organomolybdenum compound containing the ligand is added. I won't. The total number of carbon atoms present in all of the hydrocarbyl groups of the ligand of the organomolybdenum compound is suitably at least 21, preferably at least 25, more preferably at least 30, even more preferably at least 35, typically, for example: 21-800. For example, the number of carbon atoms in each hydrocarbyl group is generally in the range 1-100, preferably 1-40, more preferably 3-20. Antioxidants containing trinuclear organomolybdenum compounds form a minor component of the total lubricating oil composition. For example, the trinuclear organo-molybdenum compound is about 0.05-5.00 w of the total composition.
Contains t%. That is, the molybdenum metal is suitably about 25-3000 p of the total composition.
pm, preferably about 50-1000 ppm, more preferably about 100-500 ppm.

The antioxidants of the present invention can be used with any of the conventional dispersants previously used in lubricating oil compositions. Examples of such dispersants include, among others, polyalkylene succinimides, Mannich condensation products of polyalkylphenol-formaldehyde polyamines or borated derivatives thereof. However, it is preferred to use ashless dispersants, such as ashless succinimides, in particular polyamines, for example polyisobutenyl succinimide of tetraethylenepentamine or its homologues, benzylamine ashless dispersants or ester ashless dispersants. The dispersant is used in the composition of the present invention in an amount generally in the range of about 2 to 10% by weight, preferably about 4 to 8% by weight, based on the total weight of the lubricating oil composition. Generally, these lubricating oil compositions contain additives commonly used in lubricating oils, especially crankcase lubricants, such as antiwear additives, detergents, dispersants, rust inhibitors, viscosity index improvers. Agents, extreme pressure agents, friction modifiers, corrosion inhibitors, emulsification aids, pour point depressants, defoamers and the like. A feature of the present invention is that a lubricating oil composition containing relatively little saturated base oil and a trinuclear organomolybdenum compound unexpectedly improves oxidation control and significantly reduces fuel consumption. The present invention will be described more specifically with reference to the following examples.

Example General Procedure: A series of test oils was prepared. These oils were then tested in a bench test conducted with 40 ppm iron from ferric acetylacetone ferric iron catalyzed at 165 ° C. under a nitrogen / air mixed flow. The flow rates of air and nitrogen are 500 ml / min and
It was controlled at 350 ml / min. The following commercially available materials were used in these tests. Paranox ® 106 = polyisobutenyl succinimide dispersant (eg,
(Inphenium, Linden, NJ) Molyvan® 822 = molybdenum dithiocarbamate molybdenum dithiocarbamate (eg RT Vanderbilt) PDN5203 = experimental trinuclear molybdenum dithiocarbamate containing 5% w / w molybdenum

Example AC Comparison of Group I base oils with Group II base oils: Table 1 below shows the composition of the test oils used in these examples and their respective viscosity changes after a 48 hour oxidation test.

[0011]

[Table 1] Table 1 ^* Contains 11.5% wt of molybdenum

From the above, it can be seen that the molybdenum trinuclear dithiocarbamate exhibits better performance in Group I low saturates base oils than Group II high saturates base oils.

Example DI Comparison of Trinuclear Molybdenum Compound and Dinuclear Molybdenum Compound Table 2 below shows the composition of the test oils in Example DI and the respective changes in the viscosity data after the 32-hour oxidation test.

[0014]

[Table 2] Table 2

From Example DI it can be seen that the molybdenum trinuclear dithiocarbamate exhibits significantly better performance in controlling oxidation than the conventional molybdenum dinuclear dithiocarbamate. The performance of trinuclear molybdenum compounds is further enhanced in Group I base oils when compared to Group II base oils.

[0016] shows the viscosity change after 48 hours oxidation test in Example JM Example JM in Table 3 below.

[0017]

[Table 3] Table 3

[0018]   From Examples J-M, conventional dinuclear dithiocarba in controlling oxidation of Group I base oils. It proves to perform better over a longer period of time than molybdenum mimate.

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Claims (10)

[Claims] 1. A lubricating oil composition comprising a large amount of Group I base stock and the following general formula: Mo ₃ S _x- (Q) (I) (where x is 4 to 10 and Q is the core). Group, which may be a ligand.), The composition comprising an oil-soluble trinuclear organomolybdenum compound having an antioxidant. 2. The KV _{100 of the} base stock is 2 × 10 ^{−6 to} 20 × 10 ⁻⁶ m ² / sec (2
~ 20 cSt), sulfur content> 0.03% w / w (300 ppm) and saturates content <9
The composition of claim 1, wherein the composition is 0% w / w. 3. A ligand wherein the core group Q is capable of rendering the organomolybdenum compound of formula (I) oil soluble and ensuring that the charge of said molybdenum compound is substantially neutral. The composition according to claim 1 or 2, wherein: 4. The trinuclear organomolybdenum compound has the formula (II): Mo ₃ S _{x Ly} (II), wherein L is a ligand and y renders the compound of formula (I) oil soluble. 4. The composition according to any one of claims 1 to 3, having a sufficient number, kind and charge to make the charge of the compound of the formula (I) neutral as a whole. 5. The ligand “L” is a dihydrocarbyl dithiocarbamate of the structure (—S ₂ CNR ₂ ), where the dihydrocarbyl group, R ₂ imparts oil solubility to the molybdenum compound. The composition as described. 6. A composition according to claim 5, wherein the group R is a substituent having a carbon atom directly attached to the rest of the ligand and is predominantly hydrocarbyl in nature. 7. The total number of carbon atoms present in all of the hydrocarbyl groups of the organomolybdenum compound ligand is at least 21.
The composition according to paragraph 1. 8. The trinuclear organomolybdenum compound is present in the composition in an amount of about 1% of the total composition.
The composition according to any one of claims 1 to 7, which is present in an amount of 0.05 to 5.0% w / w. 9. The molybdenum metal in the composition is about 25-3000 p of the total composition.
The composition according to any one of claims 1-8, which is present in an amount of pm. 10. The kinematic viscosity (KV ₁₀₀ ) at 100 ° C. is about 2 × 10 ⁻⁶ m ² / sec to 50 ×.
10 ^-6 m ² / sec (2 cSt to 50 cSt) and saturates content <90% w / w, aromatics content> 10%
A method of improving the oxidative stability of a lubricating oil composition comprising a Group I basestock having a w / w and sulfur content of> 0.03% w / w (300 ppm), said basestock having the following general formula: Mo ₃ S _x- (Q) (I) (in the formula, x is 4 to 10, preferably 7, Q is a core group and may be a ligand). The method, comprising the step of adding an effective amount of an antioxidant comprising