KR102759014B1 - Lubricants for wet clutch systems - Google Patents

Abstract

The present invention relates generally to lubricating compositions useful for vehicles such as industrial machinery, and particularly for transport, construction and agricultural machinery. A method for maintaining friction in a vehicle comprising the step of lubricating the vehicle with the lubricating composition is also disclosed.

Description

Lubricants for wet clutch systems

The present invention relates generally to lubricating compositions useful for industrial machinery, and particularly for transport, construction and agricultural machinery.

Lubricants for automatic transmissions, referred to as automatic transmission fluids, have been used to assist in the smooth operation of automatic transmissions installed in automobiles, trucks, construction equipment, and other vehicles. These include torque converters, gear mechanisms, wet clutches, and hydraulic systems.

It is well known that lubricant additives affect the frictional properties of wet clutches and steel plates. The additive effects are caused by both their physical and chemical absorption onto the clutch material, e.g. cellulose, aramid (natural and synthetic) fibers, silica, and the steel plate surface.

Diesel engine oils are widely used in internal combustion engines such as automotive heavy equipment as well as construction machinery diesel engine systems in Asia, especially in Japan. Some construction machines are equipped with wet clutch systems in many systems that control not only the transmission but also the steering, parking brake, traction and power operating torque. The wet clutch (static) friction between the clutch material and steel in the lubricating fluid is very important for efficient transmission of engine power. In addition, the wet clutch static friction coefficient is dependent on the wet clutch torque capacity. Engine oils are widely used in transmissions and hydraulic systems of construction machines, and their wet clutch systems. It is important to maintain a higher (static) friction coefficient of wet clutches to operate safely and efficiently transmit power to construction machines. If the lubricant provides poor friction performance, it will result in power loss, slow response of machine operation which can have a negative impact on safety when operating the machine, or uncomfortable vibrations with high noise from lock-up of the wet clutch in the transmission.

The present invention seeks a solution for maintaining a high coefficient of friction of wet clutches, which is important not only in construction equipment but also in transmissions and motorcycle lubricants equipped with wet clutches.

According to one embodiment of the present invention, a lubricating oil composition is provided, the lubricating oil composition comprising:

(a) Oil with a high lubricating viscosity;

(b) calcium-containing detergents;

(c) At least 800 ppm Mg from magnesium-containing detergents;

(d) contains less than 600 ppm N from a nitrogen-containing dispersant;

wherein the lubricating oil composition has a phosphorus content of 0.06 to 0.15 wt%, a sulfur content of less than 0.5 wt%, and a sulfated ash content of more than 0.8 wt% to 2.0 wt%,

Here, the mass ratio of Ca to Mg is 1:2 to 4:1, and

In this case, the lubricating oil composition lubricates at least one of a crankcase of an internal combustion engine of a vehicle, a wet clutch, a brake, a torque converter, a gear system, a hydrostatic transmission and a hydraulic system.

According to another embodiment of the present invention, a method for maintaining friction in a vehicle is provided comprising the step of lubricating the vehicle with a lubricating composition, said lubricating composition comprising:

(a) Oil with a high lubricating viscosity;

(b) calcium-containing detergents;

(c) At least 800 ppm Mg from magnesium-containing detergents;

(d) contains less than 600 ppm N from a nitrogen-containing dispersant;

wherein the lubricating oil composition has a phosphorus content of 0.06 to 0.15 wt%, a sulfur content of less than 0.5 wt%, and a sulfated ash content of more than 0.8 wt% to 2.0 wt%,

Here, the mass ratio of Ca to Mg is 1:2 to 4:1, and

Here, the lubricating oil composition lubricates at least one of a crankcase of an internal combustion engine of the vehicle, a wet clutch, a brake, a torque converter, a gear system, a hydrostatic transmission and a hydraulic system.

In order to facilitate understanding of the subject matter disclosed herein, many of the terms, abbreviations, or other shorthand used herein are defined below. Any term, abbreviation, or shorthand not defined is to be understood to have its ordinary meaning used by one of ordinary skill in the art at the time of filing of this application.

Definitions

In this specification, the following words and expressions, when used, have the following meanings.

“A large amount” means more than 50% by weight of the composition.

“Minor amount” means less than 50% by weight of the composition, expressed in relation to the additive mentioned and to the total mass of all additives present in the composition, which is considered to be the active ingredient of the additive or additives.

“Active ingredients” or “active substances” refer to additive substances that are not diluents or solvents.

All percentages reported are weight percent of active ingredient units (i.e., independent of carrier or diluent oils) unless otherwise stated.

The abbreviation "ppm" means parts per million by weight based on the total weight of the lubricant composition.

High temperature high shear (HTHS) viscosity at 150°C was determined according to ASTM D4683.

Dynamic viscosity at 100℃ (KV ₁₀₀ ) was determined according to ASTM D445.

Metal - The term "metal" refers to the alkali metals, alkaline earth metals, or mixtures thereof.

The expression oil solubility or dispersibility is used throughout this specification and claims. Oil solubility or dispersibility means that the material can be incorporated by being dissolved, dispersed, or suspended in an oil of lubricating viscosity in an amount necessary to provide the desired level of activity or performance. Typically, this means that at least about 0.001% by weight of the material can be incorporated into the lubricating oil composition. For further discussion of the terms oil solubility and dispersibility, and particularly "stable dispersibility," reference is made to U.S. Pat. No. 4,320,019, which is expressly incorporated herein by reference for the relevant teachings thereon.

The term "sulfated ash" as used herein refers to non-combusted residues resulting from detergents and metallic additives in lubricating oils. Sulfated ash can be determined using ASTM Test D874.

The term "Total Base Number" or "Total Base Number (TBN)" as used herein refers to the amount of base per milligram of KOH per gram of sample. Therefore, a higher TBN value reflects more alkaline products and therefore greater alkalinity. TBN was determined using the ASTM D 2896 test.

Boron, calcium, magnesium, molybdenum, phosphorus, sulfur and zinc contents were determined according to ASTM D5185.

Nitrogen content was determined according to ASTM D4629.

All ASTM standards referenced herein are the most current versions as of the filing date of this application.

Unless otherwise specified, all percentages are weight percentages.

While the present disclosure may take various modifications and alternative forms, specific embodiments of the present disclosure are described in detail herein. It should be understood, however, that the description of specific embodiments herein is not intended to limit the disclosure to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

It should be noted that not all of the activities described in the general description or examples are required, that some portions of a particular activity may not be required, and that one or more additional activities may be performed in addition to those described. Furthermore, the order in which the activities are listed is not necessarily the order in which they will be performed.

Advantages, other advantages, and solutions to problems have been described herein with respect to specific embodiments. However, the advantages, other advantages, solutions to problems, and other feature(s) which cause any advantage, advantage, or solution to appear or become more pronounced should not be regarded as a critical, required, or essential feature of any or all of the claims.

The examples and description of the embodiments described herein are intended to provide a general understanding of the structure of various embodiments.

As used herein, the terms "consisting of," "comprises," "comprising," "including," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited to those features, but may include other features inherent to such process, method, article, or apparatus or other features not expressly listed. Additionally, unless expressly stated to the contrary, "or" means inclusive-or and not exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), or both A and B are true (or present).

The use of "a" or "an" is used to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the embodiments of the present disclosure. This description should be read to include one or at least one and the singular should also include the plural or vice versa, unless the meaning clearly differs. When referring to a value, the term "averaged" is intended to mean the mean, geometric mean, or median. The group numbers corresponding to the columns in the Periodic Table of the Elements use the "New Notation" convention found in the CRC Handbook of Chemistry and Physics, 81st Edition (2000-2001).

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The materials, methods, and examples are illustrative only and are not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing operations are conventional and can be found in textbooks and other sources within the oil and gas industries as well as lubricants.

The specification and examples are not intended to serve as a complete and comprehensive description of all of the elements and features of the formulations, compositions, devices, and systems that utilize the structures or methods described herein. Separate embodiments may also be provided in combination in a single embodiment, and conversely, various features that are, for brevity, described in the context of a single embodiment may also be provided separately or in any sub-combination. Additionally, reference to values specified as a range includes each and every value within that range. Many other embodiments may become apparent to those skilled in the art only after reading this specification. Other embodiments may be utilized and derived from this disclosure such that structural substitutions, logical substitutions, or other changes may be made without departing from the scope of the present disclosure. Accordingly, the present disclosure is to be regarded in an illustrative rather than a restrictive sense.

According to one embodiment of the present invention, a lubricating oil composition is provided, the lubricating oil composition comprising:

(a) Oil with a high lubricating viscosity;

(b) calcium-containing detergents;

(c) At least 800 ppm Mg from magnesium-containing detergents;

(d) contains less than 600 ppm N from a nitrogen-containing dispersant;

wherein the lubricating oil composition has a phosphorus content of 0.06 to 0.15 wt%, a sulfur content of less than 0.5 wt%, and a sulfated ash content of more than 0.8 wt% to 2.0 wt%,

Here, the mass ratio of Ca to Mg is 1:2 to 4:1, and

In this case, the lubricating oil composition lubricates at least one of a crankcase of an internal combustion engine of a vehicle, a wet clutch, a brake, a torque converter, a gear system, a hydrostatic transmission and a hydraulic system.

In one embodiment of the present invention, the vehicle is an industrial machine, an automobile, a truck, or other vehicle. In another embodiment, the industrial machine is a transportation, construction, or agricultural machine.

In one embodiment, the transport machine is a bus or truck equipped with a diesel engine and a hydraulic system.

In one embodiment, the construction machine is equipped with a diesel engine, a Hydro Static Transmission (HST), a power shift transmission with wet clutches, and a hydraulic system.

In one embodiment, the agricultural machine has a diesel engine, a Hydro Static Transmission (HST), a power shift transmission with wet clutches, and a hydraulic system.

In another embodiment, the vehicle is equipped with an automatic transmission, or a continuously variable transmission.

In another embodiment, a method for maintaining friction in a vehicle is provided, comprising the step of lubricating the vehicle with a lubricating composition, the lubricating composition comprising:

(a) Oil with a high lubricating viscosity;

(b) calcium-containing detergents;

(c) At least 800 ppm Mg from magnesium-containing detergents;

(d) contains less than 600 ppm N from a nitrogen-containing dispersant;

wherein the lubricating oil composition has a phosphorus content of 0.06 to 0.15 wt%, a sulfur content of less than 0.5 wt%, and a sulfated ash content of more than 0.8 wt% to 2.0 wt%,

Here, the mass ratio of Ca to Mg is 1:2 to 4:1, and

In this case, the lubricating oil composition lubricates at least one of a crankcase of an internal combustion engine of a vehicle, a wet clutch, a brake, a torque converter, a gear system, a hydrostatic transmission and a hydraulic system.

Oil of lubricating viscosity/ Oil (Base Oil) Component

An oil of lubricating viscosity (sometimes referred to as a "base stock" or "base oil") is the primary liquid component of a lubricant into which additives and possibly other oils are mixed to produce the final lubricant (or lubricant composition). Base oils are useful for making concentrates as well as for making lubricant compositions therefrom, and may be selected from natural and synthetic lubricating oils and combinations thereof.

Natural oils include animal and vegetable oils, liquid petroleum oils, and hydrorefined, solvent-treated mineral lubricating oils of the paraffinic, naphthenic, and mixed paraffinic-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils.

Synthetic lubricants include hydrocarbon oils such as polymerized and copolymerized olefins (e.g., polybutylene, polypropylene, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexene), poly(1-octene), poly(1-decene); alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di(2-ethylhexyl)benzene); polyphenols (e.g., biphenyl, terphenyl, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and derivatives, analogs and homologs thereof.

Another suitable class of synthetic lubricants include esters of dicarboxylic acids (e.g., malonic acid, alkyl malonic acids, alkenyl malonic acids, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, fumaric acid, azelaic acid, suberic acid, sebacic acid, adipic acid, linoleic acid dimer, phthalic acid) with various alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol). Specific examples of such esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and complex esters formed by reacting 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid with 1 mole of sebacic acid.

Esters useful as synthetic oils also include those made from C ₅ to C ₁₂ monocarboxylic acids and polyols, and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.

The base oil may be derived from Fischer-Tropsch synthesis hydrocarbons. Fischer-Tropsch synthesis hydrocarbons are made from synthesis gas containing H ₂ and CO using a Fischer-Tropsch catalyst. These hydrocarbons typically require further processing to become useful as a base oil. For example, the hydrocarbons may be: hydroisomerized; hydrocracked and hydroisomerized; dewaxed; or hydroisomerized and dewaxed, using processes known to those skilled in the art.

Unrefined, refined and re-refined oils may be used in the present lubricating oil compositions. Unrefined oils are those obtained directly from natural or synthetic sources without further refining treatment. For example, shale oil obtained directly from retorting operations, petroleum oil obtained directly from distillation, or ester oil obtained directly from an esterification process would be an unrefined oil. Refined oils are similar to unrefined oils except that they have been further processed in one or more refining steps to improve one or more properties. Many of these refining techniques, such as distillation, solvent extraction, acid or base extraction, filtration and percolation, are known to those skilled in the art. Re-refined oils are obtained by processes similar to those used to obtain refined oils that are applied to refined oils already in service. Such re-refined oils are also known as regenerated or reprocessed oils, and are usually further processed by techniques for the removal of spent additives and oil degradation products.

Accordingly, the base oil that can be used to prepare the present lubricating oil composition can be selected from any of the base oils of Groups I-V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines (API Publication 1509). These base oil groups are summarized in Table 1 below:

Table 1

^(a) Groups I-III are mineral oil base stocks.

^(b) Determined according to ASTM D2007.

^(c) Determined in accordance with ASTM D2622, ASTM D3120, ASTM D4294, or ASTM D4927.

^(d) Determined in accordance with ASTM D2270.

Suitable base oils for use herein include any of the various ones corresponding to API Group I, II, Group III, Group IV, and Group V oils, and combinations thereof.

The base oil constitutes the main component of the present lubricating oil composition and is present in an amount ranging from 50 to 99 wt% (e.g., 70 to 95 wt%, or 85 to 95 wt%).

Typically, the level of sulfur in the lubricating oil compositions of the present invention is less than or equal to about 0.7 wt %, based on the total weight of the lubricating oil composition, for example, a level of sulfur of from about 0.01 wt % to about 0.70 wt %, from 0.01 to 0.6 wt %, from 0.01 to 0.5 wt %, from 0.01 to 0.4 wt %, from 0.01 to 0.3 wt %, from 0.01 to 0.2 wt %, or from 0.01 to 0.10 wt %. In one embodiment, the level of sulfur in the lubricating oil compositions of the present invention is about 0.60 wt % or less, about 0.50 wt % or less, about 0.40 wt % or less, about 0.35 wt % or less, about 0.34 wt % or less, about 0.33 wt % or less, about 0.32 wt % or less, about 0.31 wt % or less, or about 0.30 wt % or less, based on the total weight of the lubricating oil composition.

In one embodiment, the level of phosphorus in the lubricating oil compositions of the invention is less than or equal to about 0.15 wt %, based on the total weight of the lubricating oil composition. In one embodiment, the level of phosphorus in the lubricating oil compositions of the invention is less than or equal to about 0.06 wt %, based on the total weight of the lubricating oil composition. In one embodiment, the level of phosphorus in the lubricating oil compositions of the invention is less than or equal to about 0.14 wt %, based on the total weight of the lubricating oil composition, for example, a level of phosphorus of from about 0.06 wt % to about 0.14 wt %, based on the total weight of the lubricating oil composition. In one embodiment, the level of phosphorus in the lubricating oil compositions of the invention is less than or equal to about 0.13 wt %, based on the total weight of the lubricating oil composition, for example, a level of phosphorus of from about 0.06 wt % to about 0.13 wt %. In one embodiment, the level of phosphorus in the lubricating oil compositions of the present invention is less than or equal to about 0.12 wt %, for example, a level of phosphorus of from about 0.06 wt % to about 0.12 wt %, based on the total weight of the lubricating oil composition.

In one embodiment, the level of sulfated ash produced by the lubricating oil compositions of the present invention is no greater than about 1.60 wt % as determined by ASTM D 874, for example, a level of sulfated ash of from about 0.80 to about 1.60 wt % as determined by ASTM D 874. In one embodiment, the level of sulfated ash produced by the lubricating oil compositions of the present invention is no greater than about 1.50 wt % as determined by ASTM D 874, for example, a level of sulfated ash of from about 0.80 to about 1.50 wt % as determined by ASTM D 874. In one embodiment, the level of sulfated ash produced by the lubricating oil compositions of the present invention is no greater than about 1.40 wt % as determined by ASTM D 874, for example, a level of sulfated ash of from about 0.80 to about 1.40 wt % as determined by ASTM D 874.

Suitably, the lubricating oil composition can have a total base number (TBN) of from 8 to 16 mg KOH/g. In some embodiments, the lubricating oil composition can have a total base number (TBN) of from 10 to 16 mg KOH/g, from 10 to 14 mg KOH/g, from 10 to 13 mg KOH/g, or from 10 to 12 mg KOH/g.

In some embodiments, for example, the desired grade of oil is SAE viscosity grade 0W-30, 0W-40, 5W-30, 10W-30, 10W-40, 10W-50, 15W-30, 15W-40, 20W-50, 30, 40 and similar.

Detergent mixture

The detergent mixture comprises at least one calcium-containing detergent and at least one magnesium-containing detergent.

A typical detergent is an anionic substance comprising a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as sulfuric acid, carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal.

Salts containing significant stoichiometric amounts of the metal are described as neutral salts, having a total base number (TBN) of from 0 to 80 mg KOH/g. Many compositions are overbased, which contain a large amount of metal base achieved by reacting an excess of metal compound (e.g., metal hydroxide or oxide) with an acid gas (e.g., carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly overbased.

It is preferred that at least some of the detergent used in the detergent mixture be overbased. The overbased detergents help to neutralize acidic impurities generated by the combustion process and become trapped in the oil. Typically, the overbased material has a ratio of metallic ion to anionic moieties of from 1.05:1 to 50:1 (e.g., from 4:1 to 25:1) on an equivalent basis. The resulting detergent is an overbased detergent having a TBN of typically 150 mg KOH/g or greater (e.g., 250 or 450 mg KOH/g or greater). Mixtures of detergents of different TBNs may be used.

In some embodiments, the overbased detergents can be low overbased, for example, the overbased salt has a TBN of less than 100 on an active basis. In one embodiment, the TBN of the low overbased salt can be from about 30 to about 100. In another embodiment, the TBN of the low overbased salt can be from about 30 to about 80. In some embodiments, the overbased detergents can be intermediate overbased, for example, the overbased salt has a TBN of from about 100 to about 250. In one embodiment, the TBN of the intermediate overbased salt can be from about 100 to about 200. In one embodiment, the TBN of the intermediate overbased salt can be from about 125 to about 175. In some embodiments, the overbased detergents can be highly overbased, for example, the overbased salt has a TBN of greater than 250. In one embodiment, the TBN of the highly overbased salt can be from about 250 to about 800, based on active material.

Suitable detergents include metal salts of sulfonates, phenates, carboxylates, phosphates, and salicylates.

Sulfonates can be prepared from sulfonic acids, which are typically obtained by sulfonation of alkyl-substituted aromatic hydrocarbons such as those obtained from the fractionation of petroleum or by the alkylation of aromatic hydrocarbons. Examples include those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl or halogen derivatives thereof. The alkylation can be carried out in the presence of a catalyst with an alkylating agent having from about 3 to about 70 or more carbon atoms. Alkaryl sulfonates generally contain from about 9 to about 80 or more carbon atoms (e.g., from about 16 to about 60 carbon atoms) per alkyl substituted aromatic moiety.

Phenates can be prepared by reacting an alkaline earth metal hydroxide or oxide (e.g., CaO, Ca(OH) ₂ , MgO, or Mg(OH) ₂ ) with an alkyl phenol or a sulfurized alkylphenol. Useful alkyl groups include straight or branched chain _C1 to _C30 (e.g., _C4 to _C20 ) alkyl groups, or mixtures thereof. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that the starting alkylphenol may include more than one alkyl substituent, each of which is independently straight or branched. When non-sulfurized alkylphenols are used, the sulfurized products can be obtained by methods well known in the art. These methods involve heating a mixture of an alkylphenol and a sulfurizing agent (e.g., elemental sulfur, a sulfur halide such as sulfur dichloride, and the like), and then reacting the sulfurized phenol with an alkaline earth metal base.

Salicylates can be prepared by reacting a basic metal compound with at least one carboxylic acid and removing water from the reaction product. Detergents prepared from salicylic acid are one class of detergents prepared from carboxylic acids. Useful salicylates include long-chain alkyl salicylates.

Hydrocarbyl-substituted salicyl acids can be prepared from phenol by the Kolbe reaction (see U.S. Pat. No. 3,595,791). Metal salts of hydrocarbyl-substituted salicyl acids can be prepared by double decomposition of the metal salt in a polar solvent such as water or alcohol.

Alkaline earth metal phosphates are also used as detergents and are known in the art.

Preferred calcium-containing detergents include calcium sulfonates, calcium phenates, and calcium salicylates, particularly calcium sulfonates, calcium salicylates, and mixtures thereof.

Calcium Detergent

In one embodiment, the calcium-containing detergent comprises calcium sulfonate, calcium phenate, and calcium salicylate.

The calcium-containing detergent can be used in an amount that provides at least 1000 ppm, at least 1050 ppm, at least 1100 ppm, at least 1150 ppm, at least 1200 ppm, at least 1250 ppm, at least 1300 ppm, at least 1350 ppm, at least 1400 ppm, at least 1450 ppm, at least 1500 ppm, at least 1550 ppm, at least 1600 ppm, at least 1650 ppm, at least 1700 ppm, at least 1750 ppm, at least 1800 ppm, at least 1850 ppm, at least 1900 ppm, at least 1950 ppm, at least 2000 ppm of calcium by weight of the lubricating oil composition. In one embodiment, the calcium content is less than or equal to 4000 ppm, less than or equal to 3500 ppm, or less than or equal to 3000 ppm by weight of the calcium to lubricant composition.

In some embodiments, the calcium-containing detergent can be a highly overbased detergent, a medium overbased detergent, or a low overbased detergent.

Magnesium Detergent

Preferred magnesium-containing detergents include magnesium sulfonate, magnesium phenate, and magnesium salicylate, particularly magnesium sulfonate.

The magnesium-containing detergent can be used in an amount that provides at least 800 ppm, at least 850 ppm, at least 900 ppm, at least 950 ppm, at least 1000 ppm, at least 1050 ppm, at least 1100 ppm, at least 1150 ppm, at least 1200 ppm, at least 1250 ppm, at least 1300 ppm, at least 1350 ppm, at least 1400 ppm, at least 1450 ppm, at least 1500 ppm, at least 1550 ppm, at least 1600 ppm, at least 1650 ppm, at least 1700 ppm, at least 1750 ppm, at least 1800 ppm, at least 1850 ppm, at least 1900 ppm, at least 1950 ppm, at least 2000 ppm of magnesium by weight in the lubricating oil composition. In one embodiment, the magnesium content is 4000 ppm or less, 3500 ppm or less, 3000 ppm or less, or 2500 ppm or less, by weight of magnesium in the lubricating oil composition. In one embodiment, the magnesium content is 800 to 2500 ppm, 900 to 2300 ppm, 1100 to 2300 ppm, 1300 to 2300 ppm, or 1500 to 2300 ppm, by weight of magnesium in the lubricating oil composition.

In some embodiments, the magnesium-containing detergent can be a high overbased detergent, a medium overbased detergent, or a low overbased detergent. In one embodiment, the mass ratio of calcium to magnesium in the lubricating oil composition is from 0.5:1 to 4:1. In other embodiments, the mass ratio of calcium to magnesium in the lubricating oil composition is from 0.6:1 to 3.5:1, from 0.6:1 to 3.0:1, from 0.6:1 to 2.5:1, from 0.6:1 to 2.0:1, from 0.6:1 to 1.7:1, from 0.6:1 to 1.5:1, from 0.6:1 to 1.3:1.

Nitrogen containing dispersant

Dispersants maintain suspended solids resulting from oxidation during engine operation that are insoluble in the oil, thereby preventing sludge coagulation and precipitation or deposition on metal parts. Dispersants useful herein include nitrogen-containing, ashless (metal-free) dispersants known to be effective in reducing the formation of deposits in gasoline and diesel engines.

Suitable dispersants include hydrocarbyl succinimides, hydrocarbyl succinamides, mixed esters/amides of hydrocarbyl-substituted succinic acids, hydroxyesters of hydrocarbyl-substituted succinic acids, and Mannich condensation products of hydrocarbyl-substituted phenols, formaldehyde, and polyamines. Also suitable are condensation products of polyamines and hydrocarbyl-substituted phenyl acids. Mixtures of such dispersants may also be used.

Basic nitrogen-containing ashless dispersants are well-known lubricant additives and methods for their preparation are extensively described in the patent literature. Preferred dispersants are alkenyl succinimides and succinamides, wherein the alkenyl substituent is preferably a long chain of more than 40 carbon atoms. These materials are readily prepared by reacting a hydrocarbyl-substituted dicarboxylic acid material with a molecule containing an amine functionality. Examples of suitable amines are polyamines such as polyalkylene polyamines, hydroxy-substituted polyamines and polyoxyalkylene polyamines.

Particularly preferred ashless dispersants are polyisobutenyl succinimide formed from polyisobutenyl succinic anhydride and polyalkylene polyamines such as polyethylene polyamines of the formula:

NH ₂ (CH ₂ CH ₂ NH) _z H

Here, z is 1 to 11. The polyisobutenyl group is derived from polyisobutene and preferably has a number average molecular weight (Mn) in the range of 700 to 3000 daltons (e.g., 900 to 2500 daltons). For example, the polyisobutenyl succinimide can be a bis-succinimide derived from a polyisobutenyl group having a Mn of 900 to 2500 daltons.

As is known in the art, the dispersant may be post-treated (e.g., with a boronating agent or a cyclic carbonate).

Nitrogen-containing ashless (metal-free) dispersants are basic and contribute to the TBN of lubricating oil compositions to which they are added without introducing additional sulfated ash.

The dispersant can be present in an amount to provide less than 600 ppm of nitrogen to the lubricating oil composition, less than 550 ppm, less than 500 ppm, less than 450 ppm, or less than 400 ppm of nitrogen by weight of the lubricating oil composition.

Other lubricant additives

In addition to the additive compounds described herein, the lubricating oil composition may include additional lubricating oil additives.

The lubricating compositions of the present disclosure may also include other conventional additives which impart or improve any desirable properties of the lubricating composition in which such additives are dispersed or dissolved. Any additive known to those skilled in the art may be used in the lubricating compositions disclosed herein. Some suitable additives are described in "Chemistry and Technology of Lubricants" by Mortier et al., 2nd Edition, London, Springer, (1996); and "Lubricant Additives: Chemistry and Applications" by Leslie R. Rudnick, 2nd Edition, London, Springer, (1996); and "Lubricant Additives: Chemistry and Applications" by Leslie R. Rudnick, 2003, both of which are incorporated herein by reference. For example, the lubricating compositions may be mixed with antioxidants, antiwear agents, metal detergents, rust inhibitors, de-foaming agents, emulsifying agents, metal deactivators, friction modifiers, pour point depressants, anti-foaming agents, co-solvents, corrosion-inhibitors, ashless dispersants, multi-functional agents, dyes, extreme pressure agents and the like, and mixtures thereof. A variety of additives are known and commercially available. These additives, or their similar compounds, can be used to prepare the lubricating oil compositions of the present disclosure by conventional mixing procedures.

The lubricating oil composition of the present invention may include one or more antiwear agents capable of reducing friction and excessive wear. Any antiwear agent known to those skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable antiwear agents include zinc dithiophosphate, metal salts of dithiophosphate (e.g., Pb, Sb, Mo and the like), metal salts of dithiocarbamates (e.g., Zn, Pb, Sb, Mo and the like), metal salts of fatty acids (e.g., Zn, Pb, Sb and the like), boron compounds, phosphate esters, phosphite esters, amine salts of phosphoric acid esters or thiophosphoric acid esters, reaction products of dicyclopentadiene and thiophosphoric acid, and combinations thereof. The amount of antiwear agent can vary from about 0.01 wt % to about 5 wt %, from about 0.05 wt % to about 3 wt %, or from about 0.1 wt % to about 1 wt %, based on the total weight of the lubricating oil composition.

In certain embodiments, the antiwear agent is or includes a dihydrocarbyl dithiophosphate metal salt, such as a zinc dialkyl dithiophosphate compound. The metal of the dihydrocarbyl dithiophosphate metal salt can be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel or copper. In some embodiments, the metal is zinc. In other embodiments, the alkyl group of the dihydrocarbyl dithiophosphate metal salt has from about 3 to about 22 carbon atoms, from about 3 to about 18 carbon atoms, from about 3 to about 12 carbon atoms, or from about 3 to about 8 carbon atoms. In additional embodiments, the alkyl group is linear or branched.

The amount of dihydrocarbyl dithiophosphate metal salt, including zinc dialkyl dithiophosphate salt, in the lubricating composition disclosed herein is measured by its phosphorus content. In some embodiments, the phosphorus content of the lubricating composition is as disclosed herein.

The lubricating oil composition of the present invention preferably comprises an organic oxidation inhibitor in an amount of 0.01 to 5 wt%, preferably 0.1 to 3 wt%. The oxidation inhibitor may be a hindered phenol oxidation inhibitor or a diarylamine oxidation inhibitor. The diarylamine oxidation inhibitor is advantageous in providing a base derived from a nitrogen atom. The hindered phenol oxidation inhibitor is advantageous in not generating NOx gas.

Examples of hindered phenol oxidation inhibitors include 2,6-di-t-butyl-p-cresol, 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-methylenebis(6-t-butyl-o-cresol), 4,4'-isopropylidenebis(2,6-di-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-thiobis(2-methyl-6-t-butylphenol), 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and octyl 3-(3,54-butyl-4-hydroxy-3-methylphenyl)propionate, and commercial products such as, but not limited to, Irganox L135® (BASF), Naugalube 531® (Chemtura), and Ethanox 376® (SI Group).

Examples of diarylamine oxidation inhibitors include alkyldiphenylamines having mixtures of alkyl groups having from 4 to 9 carbon atoms, p,p'-dioctyldiphenylamine, phenyl-naphthylamine, phenyl-naphthylamine, alkylated-naphthylamine, and alkylated phenyl-naphthylamine.

Each of the hindered phenol oxidation inhibitor and the diarylamine oxidation inhibitor may be used alone or in combination. If desired, other oil-soluble oxidation inhibitors may be added.

In the manufacture of lubricating oil formulations, it is common practice to introduce additives in the form of active ingredient concentrates of 10 to 80 wt. % in hydrocarbon oils, for example mineral lubricating oils, or other suitable solvents.

Typically, these concentrates may be diluted to from 3 to 100, for example, from 5 to 40, parts by weight of lubricant per part by weight of the additive package to form a finished lubricant, for example, a tankcase motor oil. Of course, the purpose of the concentrate is to make handling of the various substances less difficult and cumbersome, as well as to facilitate their solution or dispersion in the final blend.

Processes for manufacturing lubricating oil compositions

The lubricating oil compositions disclosed herein can be prepared by any method known to those skilled in the art for making lubricating oils. In some embodiments, the base oil can be blended or mixed with the zirconium-containing compounds described herein. Optionally, one or more others can be added. The additives can be added to the base oil separately or simultaneously. In some embodiments, the additives are added to the base oil separately in one or more additions, and the additions can be in any order. In other embodiments, the additives are added to the base oil simultaneously, optionally in the form of an additive concentrate. In some embodiments, solubilization of the additives in the base oil can be assisted by heating the mixture to a temperature of from about 25° C. to about 200° C., from about 50° C. to about 150° C., or from about 75° C. to about 125° C.

Any mixing or dispersing equipment known to those skilled in the art can be used to blend, mix or solubilize the components. The blending, mixing or solubilizing can be accomplished with a blender, a shaker, a disperser, a mixer (e.g., planetary mixers and double planetary mixers), a homogenizer (e.g., Gaulin homogenizers and Raney homogenizers), a mill (e.g., colloid mills, ball mills and sand mills) or any other mixing or dispersing equipment known in the art.

Application of lubricating oil composition

The lubricating oil composition disclosed herein may be suitable for use as a motor oil (i.e., engine oil or cranking oil) in spark-ignition internal combustion engines, particularly direct injection and boosting engines.

The following examples are presented to illustrate embodiments of the present invention, but are not intended to limit the invention to the specific embodiments described. Unless otherwise indicated, all parts and percentages are by weight. All numbers are approximate. When a numerical range is given, it should be understood that embodiments outside the stated range may still fall within the scope of the invention. The specific details described in each example should not be construed as essential features of the invention.

Example

The following examples are intended for illustrative purposes only and do not limit the scope of the invention in any way.

Example 1

The lubricating oil composition was prepared by blending together the following components:

(a) a mixture of primary and secondary zinc dialkyldithiophosphates;

(b) a mixture of overbased phenate, overbased borated sulfonate, and low overbased calcium sulfonate detergents;

(c) highly overbased magnesium sulfonate detergent (Mg sulfonate having a TBN of 402 and a Mg content of 9.4% wt.);

(d) ethylene carbonate treated and borated succinimide dispersant;

(e) alkylated diphenylamine antioxidant

(f) conventional positive pour point depressants,

(g) Ethylene propylene based viscosity index improver,

(h) molybdenum succinimide antioxidant,

(i) foam inhibitor; and

(j) The remainder are Group I oils.

Example 2

Example 1 was repeated except that the highly overbased magnesium sulfonate had a TBN of 397 and a Mg content of 9.6% wt.

Example 3

Example 1 was repeated except that highly overbased calcium sulfonate and additional highly overbased magnesium sulfonate were added to the formulation to provide the values shown in Table 2 below.

Comparative example 1

To provide the values shown in Table 2 below, overbased magnesium sulfonate was omitted from Example 1 and replaced with a predetermined amount of highly overbased calcium sulfonate.

Comparative example 2

To provide the values shown in Table 2 below, the overbased magnesium sulfonate level was adjusted and highly overbased calcium sulfonate was added to Example 1.

Comparative example 3

To provide the values shown in Table 2 below, the overbased magnesium sulfonate level was adjusted and highly overbased calcium sulfonate was added to Example 1.

Comparative example 4

To provide the values shown in Table 2 below, the overbased magnesium sulfonate level was adjusted and highly overbased calcium sulfonate was added to Example 1.

Comparative example 5

To provide the values shown in Table 2 below, the overbased magnesium sulfonate level was adjusted and highly overbased calcium sulfonate was added to Example 1.

Microclutch Test

As a means of evaluating wet friction properties, measurements were performed based on the Test method for friction properties of hydraulic fluids for construction machinery (JCMAS P 047:2004) of the Japan Construction Machinery Association (JCMAS P 047 4). Details of the method for the micro-clutch tests are given below.

a) Operate the test device at room temperature for 5 minutes under the conditions given in the following test conditions while measuring the coefficient of friction and temperature.

b) Operate the test device at surface pressure and ambient speed until the next test temperature controlled by the electric heater of the micro clutch test equipment is reached.

c) Measure the temperature and friction coefficient while maintaining the test temperature for 5 minutes.

Test conditions

Test specimen material: Clutch disc facing material: SD1795-S

Plate Material: SS400 Steel

(Details of test piece dimensions are given in JACMAS P 047)

Test conditions: Temperature: 40, 60, 80, 100, 120, 140 ℃

Surface pressure: 392 kPa, peripheral speed: 3.0 Х 10 ^-2 m/s (rotation speed: 20 min ^-1 )

Volume of test fluid: 20 ml

For a new test clutch, a test run is required to obtain stable friction data prior to measurement. The conditions of the test run are as follows.

Temperature: Room temperature

Surface pressure: 392 kPa, peripheral speed: 3.0 Х 10 ^-2 m/s (rotation speed: 20 min ^-1 )

Friction time: 60 minutes or more

Although the present invention is described below by way of examples and comparative examples under the aforementioned microclutch test conditions, these are merely representative examples and the present invention is not limited by them in any way.

Table 2

Diesel engine oils with JASO DH-1, API CG-4, CH-4 or CI-4 are widely used for internal combustion engines as well as for hydraulic and transmission systems in industrial machinery, especially in transport, construction and agricultural machinery. It is important to obtain a higher static friction coefficient of the wet clutches in their machines in order to enable safe operation of the machines and also to provide excellent power transmission efficiency for the machines due to good response and fuel efficiency. The friction coefficient should be greater than 0.13 (0.125) for the oils at all test temperatures. It is clear that examples 1, 2 and 3 show excellent wet clutch friction in the micro clutch test.

Claims (12)

As a lubricating oil composition,
(a) Oil with a high lubricating viscosity;
(b) calcium-containing detergents;
(c) At least 800 ppm Mg from magnesium-containing detergents;
(d) contains less than 600 ppm N from a nitrogen-containing dispersant;
The lubricating oil composition has a phosphorus content of 0.06 to 0.15 wt%, a sulfur content of less than 0.5 wt%, and a sulfated ash content of more than 0.8 wt% to 2.0 wt%,
The mass ratio of Ca to Mg is 1:2 to 4:1, and
The above lubricating oil composition is a lubricating oil composition that lubricates at least one of a crankcase of an internal combustion engine of a vehicle, a wet clutch, a brake, a torque converter, a gear system, a hydrostatic transmission, and a hydraulic system. A lubricating oil composition in claim 1, wherein calcium from the calcium-containing detergent is present in the lubricating oil composition in an amount of at least 1000 ppm. A lubricating oil composition in claim 1, wherein the total base number (TBN) of the lubricating oil composition is 8 to 16 mg KOH/g as measured by ASTM D 2896. A lubricating oil composition in claim 1, wherein the sulfated ash content is 0.80 to 1.60 wt% as determined by ASTM D 874. A lubricating oil composition according to claim 1, wherein the vehicle is an industrial machine, an automobile, a truck, or other vehicle. A lubricating oil composition according to claim 5, wherein the industrial machine is a transportation, construction, or agricultural machine. A lubricating oil composition according to claim 1, wherein the vehicle is equipped with an automatic transmission or a continuously variable transmission. A method for maintaining friction in a vehicle comprising the step of lubricating the vehicle with a lubricating composition, said lubricating composition comprising:
(a) Oil with a high lubricating viscosity;
(b) calcium-containing detergents;
(c) At least 800 ppm Mg from magnesium-containing detergents;
(d) contains less than 600 ppm N from a nitrogen-containing dispersant;
The lubricating oil composition has a phosphorus content of 0.06 to 0.15 wt%, a sulfur content of less than 0.5 wt%, and a sulfated ash content of more than 0.8 wt% to 2.0 wt%,
The mass ratio of Ca to Mg is 1:2 to 4:1, and
A method for lubricating at least one of the crankcase of an internal combustion engine of a vehicle, a wet clutch, a brake, a torque converter, a gear system, a hydrostatic transmission and a hydraulic system, wherein the lubricating oil composition is used. A method in claim 8, wherein calcium from the calcium-containing detergent is present in the lubricating oil composition in an amount of at least 1000 ppm. A method according to claim 8, wherein the vehicle is an industrial machine, an automobile, a truck, or other vehicle. A method according to claim 10, wherein the industrial machine is a transport, construction, or agricultural machine. A method according to claim 8, wherein the vehicle is equipped with an automatic transmission or a continuously variable transmission.