JP2011063818A - Lubricating oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil composition suitable for use in a crankcase of an internal combustion engine. <P>SOLUTION: The lubricating oil composition comprises, as a detergent, metal salt of a long chain hydrocarbyl-substituted organic acid, at a concentration of ≤15 mmol/kg oil. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition suitable for use in a crankcase of an internal combustion engine.

It is well known that the lubricating ability of a lubricating oil composition (lubricant or simply oil) deteriorates with use in an internal combustion engine. For example, in a diesel (compression ignition) engine, the viscosity of the oil can be undesirably increased by increasing the soot level. This increase can still occur despite the presence of an ashless dispersant in the oil. An approved measurement for increasing the viscosity of diesel engines is the so-called MackT8 test, which forms part of the American Petroleum Institute (API) performance category CG-4. In order to achieve acceptable levels of performance in tests such as MackT8, it is often necessary to increase the amount of ashless dispersant present in the oil. However, this is often undesirable due to the poor seal compatibility characteristics of the dispersant and the increased likelihood of corrosion to the bearing.
The lubricating oil composition may also include a neutral or overbased metal detergent as an additive or additive component. Chemically, they consist of metal salts of organic acids such as hydrocarbyl-substituted sulfonic acids or aromatic carboxylic acids, or may be metal salts of hydrocarbyl-substituted phenols. Such metal salts are often referred to as surfactants or soaps. The hydrocarbyl substituent is of sufficient length to render the salt oil soluble, which would generally be insoluble in oils having a lubricating viscosity. The metal is usually an alkaline earth metal, but other metals can also be used. Moreover, you may use the mixture of a metal.

The term “overbasing” is intended to define an additive that contains an excess of metal content required for the stoichiometry of the particular metal used and the particular organic acid. Excess metal is present in the form of particles of an inorganic base, such as hydroxide or carbonate, covered by a metal salt sheath. The sheath functions to maintain the particles dispersed in the liquid hydrophobic vehicle. The excess of metal is generally expressed as the ratio of the total equivalents of excess metal to the equivalents of organic acid, typically 0.1-30.
The main function of the metal detergent in the lubricating oil composition is to neutralize acidic products in the oil and / or prevent deposit formation on the engine surface. Depending on the nature of the acid used, the cleaning agent may have further functions, for example antioxidant properties. Typically, the lubricating oil composition comprises a metal detergent comprising either an overbased detergent or a mixture of neutral and overbased detergents.

The present invention is based on the knowledge that the adjustment of oil viscosity can be improved without increasing the level of ashless dispersant when a low concentration surfactant is used in a lubricating oil composition in a metal detergent. Is. The metal detergent used has a long chain hydrocarbyl substituted organic acid.
Accordingly, a first aspect of the present invention is a lubricating oil comprising one or more metal salts of long chain hydrocarbyl substituted organic acids, such as selected from aromatic carboxylic acids, sulfonic acids or phenol derivatives as detergents. A composition, wherein the total concentration of the metal salt is 15 mmol or less per kg of the composition, and the composition has a base stock of less than 5% by weight of a non-conventional lubricant, for example 6 The lubricating oil composition is not a SAE 5W composition containing less than 10% by mass or less than 10% by mass. Preferably, the acid is selected from aromatic carboxylic acids or phenol derivatives.
The concentration of the metal salt is that of such a salt and does not include any overbased material (or base) in the detergent. Specifically, it has been found that low metal salt concentrations on the order of 8 mmol / kg or less of oil are sufficient to achieve performance in diesel engine testing that exceeds current specification conditions.

Thus, in accordance with the present invention, the amount of ashless dispersant required to maintain the viscosity of the lubricating oil composition within an acceptable range is reduced to an economy of, for example, 3-10% by weight, based on the weight of the composition. It becomes possible to reduce to an attractive level. The present invention also allows the lubricating oil composition to maintain a high level of performance in parts such as seals and bearings.
Surprisingly, the metal salt in salicylate form when used at the above concentrations, as demonstrated by the performance within the scope of standard US and European diesel engine tests for lubricating oil compositions, including: We found that cleaning performance superior to current standard conditions is given:
Caterpillar IK test forming part of API performance category CF-4;
Mercedes-Benz OM364A test forming part of the ACEA performance category E1-E396.
A second aspect of the present invention is a method for producing a lubricating oil composition comprising mixing a large amount of oil having a lubricating viscosity and a small amount of a metal salt as defined in the first aspect.
A third aspect of the present invention is a method for lubricating an engine comprising supplying a diesel engine with a lubricating oil composition as defined in the first aspect or produced according to the second aspect. .
A fourth aspect of the present invention is a method for reducing the viscosity increase of the composition due to the presence of elevated levels of soot when lubricating a diesel engine with a lubricating oil composition, wherein the composition comprises The method comprising using a cleaning agent as defined in one embodiment.

In the present specification, “major amount” means exceeding 50% by mass of the mass of the composition.
“Small amount” means less than 50% by weight of the composition, which is related to both the above mentioned additives and the total weight% of all additives present in the composition, and the activity of the additive. It is calculated as a component.
“Including” or similar terms specify the presence of the above features, integers, steps or components, but still have one or more of the other features, integers, steps, components and groups thereof. It does not exclude doing or adding.
“Non-conventional Lubricant (NCL)” conforms to the classification of base stock by the American Petroleum Institute (API), publication 1509, January 1993, entitled “Engine Oil Licensing and Certification System” (EOLCS) Base stocks not included in Group 1 and 2.
“SAE5W” is a viscosity standard described in the Association of Automotive Engineers (SAE) J300, that is, 3500 10 ⁻³ Pa. a maximum CCS viscosity of s, and a minimum kV of 3.8 mm ² S ⁻¹ at 100 ° C.
The various components of the composition of the present invention, essential, optimal or normal, can react under conditions of formulation, storage or use; and the present invention can be obtained or obtained as a result of such a reaction. Provide the product.

The features of the invention are described in more detail below.
Metal Salts Methods for producing metal detergents used in the present invention are known to those skilled in the art. The concentration of the metal salt is mmol per kg of oil, preferably 3 or 4 or 5 or more, more preferably 8 to 13. The metal detergent typically has a metal: metal salt molar ratio of 1-10. Examples of metal detergents that can be used in the present invention include calcium or magnesium alkyl salicylates, preferably C _14-24 alkyl salicylates. When the total base number (TBN) of the salicylate detergent measured by ASTM D2896 is used, it is preferably 50 to 450, for example 80 to 450.

Lubricating oil base stock This may be mineral oil or synthetic oil or both.
The improved viscosity control achieved by the present invention is that the oil (or basestock) having a lubricating viscosity used in the manufacture of the composition has a high level (> 85%) of saturates (ASTM Method D2007). Is further strengthened when it is a mineral oil base stock with

By reducing the metal salt content in the antioxidant composition, the antioxidant properties of the metal detergent can be limited. Accordingly, it is preferred to add an antioxidant to the lubricant formulation to counteract this effect. Antioxidants (oxidation inhibitors) increase the oxidation resistance of the composition, bind to or modify peroxides, detoxify them, or decompose peroxides, or It can function by deactivating the oxidation catalyst. Antioxidants that can be used in the present invention include amine antioxidants (such as those based on aryl or alkyl-substituted amines such as Irganox L57 (tertiary-C ₁₂ alkyldiphenylamine)), or phenol antioxidants (hinders). Dophenol and the like, for example, Irganox L135 (2,6-di-t-butyl-4- (2-carboxy (alkyl) ethyl) phenol)) (CIBA Specialty Chemicals).

Additional additives as co-additives can also be introduced into the composition to meet certain specifications. Examples include, in addition to those described above in connection with the present invention, corrosion inhibitors, antioxidants, friction coefficient improvers, dispersants, detergents / rust inhibitors, antiwear agents, pour point depressants, Antifoaming agents and viscosity improvers are mentioned.
Dispersants, described hereinafter, suspend and hold solid and liquid contaminants, thereby passivating them and reducing engine deposits while reducing sludge formation. Is an additive. Ashless dispersants include, for example, long chain hydrocarbons that provide polymerizable, oil solubility, with polar heads, eg, in the form of functional groups, for binding to the particles to be dispersed. A noteworthy class of ashless dispersants is constituted by hydrocarbon-substituted succinimides, which may be borated or non-borated.
The additives for the compositions of the present invention are typically blended into the base stock in an amount that allows them to provide their desired function. Concentrates, ie, concentrated dispersions or solutions of one or more additives, are known in the art and can be used by known means to produce the compositions of the present invention.
The composition lubricates them by supplying it to mechanical engine parts, in particular internal combustion engines. A preferred engine is a diesel (compression ignition) engine. A particularly preferred composition is a heavy duty diesel engine lubricating oil composition, i.e. for application to a large diesel engine.

The following examples illustrate the invention.
The lubricating oil compositions used in the examples contained the following components: overbased C _14-18 alkylsalicylic acid calcium salt detergent, calcium sulfonate detergent, calcium lime salt, dispersant, Abrasives (eg, diaryl or dialkyldithiophosphate zinc salts) and antioxidants. The selected ingredients were blended to obtain five different fully formulated oils with viscosity standards corresponding to the Automobile Engineers Association (SAE) standard for 15W40 multigrade oil. The oils were identical except for their detergent type and / or concentration.
Each oil was tested in a Mack T8 engine test. Table 1 shows the rate of viscosity increase at different concentrations of metal salt (or surfactant), where specific oils were identified by letter numbers A-F.

Comparison of the results of Examples A and D showed that the level of inorganic base did not affect the overall viscosity level. It is also clear that a reduction in surfactant concentration results in an improvement in viscosity level in the lubricating oil composition. The most prominent effect was achieved when using a 10 mmol salicylate surfactant concentration per kg of the lubricating oil composition.
Table 2 shows the effect of the antioxidant added in combination with the metal detergent on the viscosity increase in the Mack T8 engine test.

As indicated, the addition of phenolic or amine antioxidants causes a decrease in viscosity increase rate when compared to metal detergents lacking antioxidants.
Table 3 shows the performance of lubricating oil compositions containing a metal detergent consisting of 10 mmol salicylate surfactant and 61 mmol inorganic base per kg oil within the standard US and European engine cleanup tests.

Table 3
A. Maintained European diesel engine cleaning function (CE-L-42-A-92)

B. US diesel cleaning function, Caterpillar 1N

C. Caterpillar 1K

The results show that the lubricating oil composition comprising the metal detergent of the present invention can achieve an acceptable level of performance in each cleaning test.

Claims (16)

  A lubricating oil composition comprising one or more metal salts of long chain hydrocarbyl-substituted organic acids, such as selected from aromatic carboxylic acids, sulfonic acids or phenol derivatives, as a cleaning agent, The concentration is 15 mmol or less per kg of the composition, and the composition is not a SAE 5W composition whose base stock comprises less than 5% by weight of a non-conventional lubricant, such as less than 6% or less than 10% by weight. The lubricating oil composition characterized.   A lubricating oil composition comprising one or more overbased metal salts of long chain hydrocarbyl-substituted acids selected from aromatic carboxylic acids or phenol derivatives as a detergent, wherein the total concentration of the metal salts is 15 mmol or less per kg of the composition, wherein the composition is not a SAE 5W composition whose base stock contains less than 5% by weight of a non-conventional lubricant, such as less than 6% by weight or less than 10% by weight. The lubricating oil composition.   The composition according to claim 1 or 2, wherein the concentration is 5 to 15 mmol, for example, 8 to 13 mmol, per kg of the composition.   The composition according to any one of claims 1 to 3, wherein the metal salt is a calcium alkylsalicylate. The composition according to any one of claims 1 to 4, wherein the carboxylic acid is a _C14-24 alkyl salicylic acid.   Furthermore, the composition of any one of Claims 1-5 containing antioxidant containing amine type antioxidants, such as aryl or an alkyl substituted amine, or phenolic antioxidants, such as a hindered phenol. The composition of claim 6 wherein the antioxidant is an alkyl-substituted amine and is a t-C _4-12 alkyldiphenylamine.   The composition according to claim 6, wherein the antioxidant is phenol and 2,6-di-t-butyl-4- (2-carboxy (alkyl) ethyl) phenol.   The composition according to claim 1, wherein the detergent has a metal: metal salt ratio of 1-10.   10. A composition according to any one of claims 1 to 9, comprising a base stock in the form of a mineral oil base stock comprising a saturate higher than 85% as measured by ASTM method D2007.   Furthermore, the composition of any one of Claims 1-10 containing a dispersing agent by the density | concentration of 3-10 mass%, for example based on the mass of the said composition.   The composition according to any one of claims 1 to 11, which does not contain a magnesium salt detergent.   The composition according to any one of claims 1 to 12, which is in the form of a heavy duty diesel lubricating oil composition.   A method for producing a lubricating oil composition comprising mixing an oil having a large amount of lubricating viscosity and a small amount of a metal salt, and optionally a small amount of an antioxidant according to any one of claims 6-8.   A method for lubricating an engine comprising supplying a diesel engine with a lubricating oil composition according to any one of claims 1 to 13 or a lubricating oil composition produced by the method according to claim 14.   A method for reducing an increase in viscosity of a composition due to the presence of elevated levels of soot when lubricating a diesel engine with a lubricating oil composition comprising the metal salt 1 of claim 1 or 2 in the composition. The method comprising using one or more.