CN113493720A

CN113493720A - Low viscosity lubricating oil composition

Info

Publication number: CN113493720A
Application number: CN202110301515.5A
Authority: CN
Inventors: 田中勲; 服部大辉; 赤堀亘
Original assignee: Chevron Japan Ltd
Current assignee: Chevron Japan Ltd
Priority date: 2020-03-20
Filing date: 2021-03-22
Publication date: 2021-10-12
Also published as: CA3112718A1; US20210292677A1; JP2021147620A; SG10202102796XA; EP3882330A1

Abstract

The present invention relates generally to lubricating oil compositions for reducing NOACK volatility in finished lubricating oils for internal combustion engines. A method of reducing NOACK volatility in finished lubricating oils in such engines is also disclosed.

Description

Low viscosity lubricating oil composition

Background

The lubricating oil industry is actively conducting research related to improving fuel economy. One well-known method of improving fuel economy is to reduce the viscosity of the lubricating oil. Engine oils exhibiting excellent fuel economy performance are typically formulated as low viscosity oils. Viscosity Index Improvers (VII) are commonly used to reduce fluid friction due to viscosity drag at low temperatures. A disadvantage of low viscosity engine oils is that they may have high volatility, which results in high evaporation losses (meaning increased oil consumption).

Attempts to overcome the above problems include formulation with low volatility base oils such as esters and polyalphaolefins. However, these base oils may not be ideal for low viscosity engine oils such as 0W-12, 0W-8, and 0W-4.

Disclosure of Invention

According to one embodiment of the present invention, there is provided a lubricating oil composition comprising: a. a base oil comprising a diester having one of the following structures:

wherein each R is independently C₁-C₂₀A saturated or unsaturated alkyl group, and n is an integer of 1 to 8, wherein the diester has a kinematic viscosity at 100 ℃ of 2.5 to 3.5mm according to ASTM D445²(ii)/s, and a viscosity index according to ASTM D2270 of from 110 to 175; and 75 to 500ppm boron based on the total weight of the lubricating oil composition, wherein the boron is provided by one or more boron-containing dispersants.

According to another embodiment of the present invention, there is provided a method of reducing evaporative losses in an internal combustion engine, comprising lubricating the engine with a lubricating oil composition comprising: a base oil comprising a diester having one of the following structures:

wherein each R is independently selected from C₁-C₂₀A saturated or unsaturated alkyl group, and n is an integer of 1 to 8, wherein the diester has a kinematic viscosity at 100 ℃ of 2.5 to 3.5mm according to ASTM D445²(ii)/s, and a viscosity index according to ASTM D2270 of from 110 to 175; and 75 to 500ppm boron based on the total weight of the lubricating oil composition, wherein the boron is provided by one or more boron-containing dispersants.

According to yet another embodiment of the present invention, there is provided a method of improving the fuel efficiency of an engine, the method comprising lubricating the engine with a lubricating oil composition comprising: a base oil comprising a diester having one of the following structures:

wherein each R is independently selected from C₁-C₂₀A saturated or unsaturated alkyl group, and n is an integer of 1 to 8, wherein the diester has a kinematic viscosity at 100 ℃ of 2.5 to 3.5mm according to ASTM D445²(ii)/s, and a viscosity index according to ASTM D2270 of from 110 to 175; and based on the lubricating oil75 to 500ppm boron, based on the total weight of the composition, wherein the boron is provided by one or more boron-containing dispersants.

Detailed Description

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

To facilitate an understanding of the subject matter disclosed herein, some terms, abbreviations, or other abbreviations used herein are defined below. Any terms, abbreviations or acronyms that are not defined are understood to have the ordinary meaning as used by those skilled in the art contemporaneously with the filing of this application.

Definition of

The following terms used in the present specification have the following meanings unless explicitly stated to the contrary. In this specification, the following words and expressions, if and when used, have the meanings given below.

By "major amount" is meant more than 50% by weight of the composition.

By "minor amount" is meant less than 50% by weight of the composition, calculated as active ingredient of the additive or additives, with respect to the said additives and with respect to the total mass of all additives present in the composition.

"active ingredient" or "active" or "oil-free" refers to an additive material that is not a diluent or solvent.

All percentages reported are by weight on an active ingredient basis (i.e., without regard to carrier or diluent oils), unless otherwise indicated.

The abbreviation "ppm" refers to parts per million by weight based on the total weight of the lubricating oil composition.

High Temperature High Shear (HTHS) viscosity at 150 ℃ was determined according to ASTM D4683.

Kinematic Viscosity (KV) at 100 ℃₁₀₀) Measured according to ASTM D445.

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

The term "oil-soluble" or "dispersancy" is used to indicate that an amount which provides the desired level of activity or performance can be incorporated into an oil of lubricating viscosity by dissolving, dispersing or suspending. Typically, this means that at least about 0.001 wt.% of the material can be incorporated into the lubricating oil composition. For further discussion of the terms oil solubility and dispersability, and in particular "stably dispersible", see U.S. patent 4,320,019, which is expressly incorporated herein by reference for relevant teachings in this regard.

The term "sulfated ash" as used herein refers to the non-combustible residue produced by detergents and metal additives in lubricating oils. Sulfated ash can be determined using ASTM test D874.

The term "total base number" or "TBN" as used herein refers to the amount of base equivalent to mg KOH in a gram of sample. Thus, a higher TBN number indicates more basic product and thus also more basicity. TBN is determined using ASTM D2896 test.

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

Nitrogen content was determined according to ASTM D4629.

NOACK volatility was determined according to either ASTM D5800A-D or ASTM D6417.

All percentages are by weight unless otherwise specified.

It is noted that not all of the activities described in the general description or the embodiments are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to the activities described. Further, the order of the activities listed are not necessarily their order of execution.

Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. The benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced, however, are not to be construed as a critical, required, or essential feature or feature of any or all the claims.

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

As used herein, the terms "comprises," "comprising," "includes," "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 only those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or, and not to an exclusive or. For example, any one of the following satisfies condition a or B: a is true (or present) and B is false (or not present), a is false (or not present) and B is true (or present), and 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 for convenience only and to give a general sense of the scope of the embodiments of the disclosure. The description is to be understood as including one or at least one and the singular also includes the plural and vice versa unless it is clearly stated otherwise. The term "average", when referring to a value, means an average, geometric mean or median. The group numbers corresponding to each column in the periodic table of elements are defined by "New notation" in CRC handbook of chemistry and Physics, 81 th edition (2001) 2000).

Unless defined otherwise, 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 document belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. For the purposes of the description not described herein, many details regarding specific materials and processing activities are conventional and may be found in textbooks and other sources within the lubricating oil and gas industries.

The specification and drawings are not intended to serve as an exhaustive or comprehensive description of all the elements and features of formulations, compositions, devices, and systems that utilize the structures or methods described herein. The various embodiments may also be provided in combination as a single embodiment, whereas, for the sake of brevity, various features which are described in the context of a single embodiment may also be provided separately or in any subcombination. Moreover, reference to values stated in ranges includes each and every value within that range. Many other embodiments will be apparent to those of skill in the art upon reading this specification. Other embodiments may be utilized and derived from the disclosure, such that structural substitutions, logical substitutions, or other changes may be made without departing from the scope of the disclosure. Accordingly, the present disclosure is to be considered as illustrative and not restrictive.

It has been found that lubricating oil compositions containing a diester base oil and a boronated dispersant provide lower NOACK volatility without increasing the viscosity of the oil. This in turn reduces evaporation losses compared to other lubricating oil compositions formulated to have low viscosities.

The present disclosure provides a lubricating oil composition comprising

a. A base oil comprising a diester having one of the following structures:

wherein each R is independently selected from C₁-C₂₀A saturated or unsaturated alkyl group, and n is an integer from 1 to 8, wherein the diester has a kinematic viscosity at 100 ℃ according to ASTM D445 of from 2.5 to3.5mm²(ii)/s, and a viscosity index according to ASTM D2270 of from 110 to 175;

b. 75 to 500ppm boron based on the total weight of the lubricating oil composition, wherein the boron is provided by one or more boron-containing dispersants.

Also disclosed is a method of reducing evaporation loss or improving fuel efficiency in an internal combustion engine comprising lubricating the engine with a lubricating oil composition comprising:

a. a base oil comprising a diester having one of the following structures:

wherein each R is independently selected from C₁-C₂₀A saturated or unsaturated alkyl group, and n is an integer of 1 to 8, wherein the diester has a kinematic viscosity at 100 ℃ of 2.5 to 3.5mm according to ASTM D445²(ii)/s, and a viscosity index according to ASTM D2270 of from 110 to 175; and

Also disclosed is the use of a lubricating oil composition in an internal combustion engine to reduce evaporative loss or improve fuel efficiency, wherein the lubricating oil composition comprises:

a. a base oil comprising a diester having one of the following structures:

The lubricating oil compositions of the present invention comprise components that act synergistically to reduce the NOACK volatility of the lubricating oil while maintaining low viscosity. These components may be particularly useful for formulating lubricating oils that exhibit desirable characteristics, such as improved engine fuel efficiency.

Base oil

In one aspect, the present disclosure provides one or more base oils. The one or more base oils include one or more diester base oils, and optionally additional base oils. The total amount of the one or more base oils is from about 50 to about 99 weight percent based on the finished lubricant.

In one embodiment, the diester has one of the following structures:

wherein each R is independently selected from C₁-C₂₀Saturated or unsaturated alkyl, and n is an integer from 1 to 8. In one embodiment, each R is independently selected from C₁-C₁₈Saturated or unsaturated alkyl groups. In one embodiment, each R is independently selected from C₁-C₁₆Saturated or unsaturated alkyl groups. In one embodiment, each R is independently selected from C₁-C₁₄Saturated or unsaturated alkyl groups. In one embodiment, each R is independently selected from C₁-C₁₂Saturated or unsaturated alkyl groups.

In one embodiment, the present disclosure provides a diester base oil in an amount from 5 to 99 wt.%, from 25 to 99 wt.%, from 50 to 99 wt.%, from 55 to 99 wt.%, from 60 to 99 wt.%, from 65 to 99 wt.%, from 70 to 99 wt.%, from 75 to 99 wt.%, from 80 to 99 wt.%, based on finished lubricant.

Typically, the diester will have a kinematic viscosity at 100 ℃ of 2.5 to 3.5mm according to ASTM D445²/s。

Typically, the diester will have a viscosity index of 110 to 175 according to ASTM D2270. In one embodiment, the diester has a viscosity index of 125 to 175, 135 to 175 according to ASTM D2270.

Boron-containing dispersant

Examples of borated dispersants include borated ashless dispersants such as borated polyalkenyl succinic anhydrides; non-nitrogen containing derivatives of boronated polyalkenyl succinic anhydrides; boronated basic nitrogen compounds selected from succinimides, carboxylic acid amides, hydrocarbyl monoamines, hydrocarbyl polyamines, mannich bases, phosphonamides, thiophosphonamides and phosphoramides, thiazoles (e.g., 2, 5-dimercapto-1, 3, 4-thiadiazole, mercaptobenzothiazole and derivatives thereof), triazoles (e.g., alkyltriazoles and benzothiazoles), copolymers containing carboxylic esters having one or more additional polar functions including amine, amide, imine, imide, hydroxyl, carboxyl, and the like (e.g., products prepared by copolymerizing long chain alkyl acrylates or methacrylates with monomers of the above functions); and the like and combinations thereof. Preferred borated dispersants are boron succinimide derivatives, such as borated polyisobutenyl succinimides.

An example of a boronated ashless dispersant is a boronated ashless hydrocarbyl succinimide dispersant prepared by reacting a hydrocarbyl succinic acid or anhydride with an amine. Preferred hydrocarbyl succinic acids or anhydrides are those in which the hydrocarbyl group is derived from C₃Or C₄Polymers of monoolefins, especially those of polyisobutylene, where the number average molecular weight (Mn) of the polyisobutylene group is from 700 to 5,000, more preferably from 900 to 2,500. Such dispersants generally have at least 1, preferably 1 to 2, more preferably 1.1 to 1.8 succinic acid groups per polyisobutenyl group. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 550 to about 5000. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 550 to about 4000.In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 550 to about 3000. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from polyisobutylene groups having a number average molecular weight of greater than 550 to about 2300. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 950 to about 2300. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of from about 950 to about 1300. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 2300. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 1300. In one embodiment, the oil-soluble or oil-dispersible borated polyisobutylene succinimide dispersant is derived from a polyisobutylene group having a number average molecular weight of about 1000.

Preferred amines for reaction to form the succinimide are polyamines having 2 to 60 carbon atoms and 2 to 12 nitrogen atoms per molecule, with the polyalkyleneamines represented by structure (3) being particularly preferred.

NH₂(CH₂)_n—(NH(CH₂)_n)_m—NH₂

Structure (3)

Wherein n is 2 to 3, and m is 0 to 10. Exemplary are ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, and the like, as well as commercially available mixtures of these polyamines. Amines containing other groups such as hydroxyl, alkoxy, amide, azide and imidazoline groups may also be used, as may polyoxyalkylene polyamines. The amine and the alkenyl succinic acid or anhydride are reacted in a conventional ratio of about 1:1 to 10:1, preferably 1:1 to 3:1, preferably about 1:1, molar ratio of alkenyl succinic acid or anhydride to polyamine, typically by heating the reactants to 100 ℃ to 250 ℃, preferably 125 ℃ to 175 ℃, for 1 to 10 hours, preferably 2 to 6 hours.

The boronation of alkenyl succinimide dispersants is also well known in the art, as disclosed in U.S. Pat. nos. 3,087,936 and 3,254,025. For example, the succinimide may be treated with a boron compound selected from boron, boron oxides, boron halides, boric acid and esters thereof in an amount to provide from 0.1 atomic proportion of boron to 10 atomic proportions of boron per atomic proportion of nitrogen in the dispersant.

The borated product will generally contain from 0.1 to 2.0, preferably from 0.2 to 0.8 weight percent boron based on the total weight of the borated dispersant. Boron is believed to be present as a polymer of dehydrated boric acid attached to the metaborate salt of the imine. The boronation reaction is readily carried out by adding 1 to 3% by weight (based on the weight of the dispersant) of the boron compound, preferably boric acid, to the dispersant in the form of a slurry in mineral oil and heating at 135 ℃ to 165 ℃ for 1 to 5 hours with stirring, and then stripping the product with nitrogen and filtering. Alternatively, boric acid may be added to the hot reaction mixture of succinic acid or anhydride and amine while removing water.

The borated dispersant is present in an amount sufficient to provide 100 to 1000ppm, 100 to 900ppm, 100 to 800ppm, 100 to 700ppm of boron based on the total weight of the lubricating oil composition.

Other dispersants

The dispersant maintains oil insoluble materials produced by oxidation during engine operation in suspension, thereby preventing sludge flocculation and precipitation or deposition on metal parts. Dispersants useful herein include nitrogen-containing, ashless (metal-free) dispersants known to be effective in reducing deposit formation when used in gasoline and diesel engines.

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

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

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

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

The dispersant may be present at 0.1 to 10 wt.% (e.g., 0.5 to 8 wt.%, 0.7 to 7 wt.%, 0.7 to 6 wt.%, 0.7 to 5 wt.%, 0.7 to 4 wt.%), based on the active level of the lubricating oil composition.

The nitrogen in the dispersant is present at greater than 0.0050 to 0.30 wt% (e.g., greater than 0.0050 to 0.10 wt%, 0.0050 to 0.080 wt%, 0.0050 to 0.060 wt%, 0.0050 to 0.050 wt%, 0.0050 to 0.040 wt%, 0.0050 to 0.030 wt%) based on the weight of dispersant in the finished oil.

Cleaning agent

Detergents that may be used include oil-soluble overbased sulfonates, non-sulfur containing phenates, sulfurized phenates, salicylates, salicides, complex detergents and naphthenate detergents, as well as other oil-soluble metal alkylhydroxybenzoate salts, especially alkali or alkaline earth metals, such as barium, sodium, potassium, lithium, calcium and magnesium. The most commonly used metals are calcium and magnesium, which may be present in detergents for lubricating oils, as well as mixtures of calcium and/or magnesium with sodium.

Overbased metal detergents are generally made from hydrocarbons, detergent acids (e.g., sulfonic acids, alkyl groups)Hydroxybenzoates, etc.), a mixture of a metal oxide or hydroxide (e.g., calcium oxide or calcium hydroxide) and a promoter (e.g., xylene, methanol, and water). For example, when overbased calcium sulphonates are prepared, calcium oxide or hydroxide reacts with gaseous carbon dioxide to form calcium carbonate during carbonation. With excess CaO or Ca (OH)₂The sulfonic acid is neutralized to form a sulfonate.

The overbased detergent may be low overbased, e.g., an overbased salt having a TBN of less than 100 on an actives basis. In one aspect, the low overbased salt may have a TBN of from about 30 to about 100. In another aspect, the low overbased salt may have a TBN of from about 30 to about 80. The overbased detergent may be moderately overbased, e.g., an overbased salt having a TBN of about 100 to about 250 on an actives basis. In one aspect, the TBN of the medium overbased salt may be from about 100 to about 200. In another aspect, the medium overbased salt may have a TBN of about 125 to about 175. The overbased detergent may be highly overbased, e.g., an overbased salt having a TBN greater than 250 on an actives basis. In one aspect, the TBN of the high overbased salt may be from about 250 to about 800 on an actives basis.

In one aspect, the cleaning agent can be one or more alkali or alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid. Suitable hydroxyaromatic compounds include mononuclear monohydroxy and polyhydroxy aromatic hydrocarbons having from 1 to 4, preferably from 1 to 3, hydroxyl groups. Suitable hydroxyaromatic compounds include phenol, catechol, resorcinol, hydroquinone, pyrogallol, cresol, and the like.

Generally, the amount of detergent may be from about 0.001 wt.% to about 50 wt.%, or from about 0.05 wt.% to about 25 wt.%, or from about 0.1 wt.% to about 20 wt.%, or from about 0.01 to 15 wt.%, based on the total weight of the lubricating oil composition.

Antiwear agent

The lubricating oil compositions disclosed herein may comprise one or more antiwear agents. The antiwear agent reduces wear of the metal parts. Suitable antiwear agents include dihydrocarbyl dithiophosphate metal salts, such as Zinc Dihydrocarbyl Dithiophosphate (ZDDP) of structure 8 below.

Zn[S-P(＝S)(OR¹)(OR²)]₂ (8)，

Wherein R is¹And R²Can likewise be different hydrocarbyl radicals having from 1 to 18, for example from 2 to 12, carbon atoms, including radicals such as alkyl, alkenyl, aryl, aralkyl, alkaryl and cycloaliphatic radicals. As R¹And R²Particularly preferred is an alkyl group having 2 to 8 carbon atoms (for example, the alkyl group may be ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, 2-ethylhexyl). To obtain oil solubility, the total number of carbon atoms (i.e., R)¹+R²) Will be at least 5. Thus, the zinc dihydroxydithiophosphate may comprise zinc dialkyldithiophosphates. The zinc dialkyldithiophosphate is primary, secondary zinc dialkyldithiophosphates, or a combination thereof. The ZDDP can be present at 3 wt.% or less (e.g., 0.1 to 1.5 wt.%, or 0.5 to 1.0 wt.%) of the lubricating oil composition. In one embodiment, the lubricating oil composition containing the magnesium salicylate detergents described herein further comprises an antioxidant compound. In one embodiment, the antioxidant is a diphenylamine antioxidant. In another embodiment, the antioxidant is a hindered phenol antioxidant. In yet another embodiment, the antioxidant is a combination of a diphenylamine antioxidant and a hindered phenol antioxidant.

Antioxidant agent

The lubricating oil compositions disclosed herein may comprise one or more antioxidants. Antioxidants reduce the tendency of mineral oils to deteriorate during use. Oxidative degradation can be manifested as sludge in the lubricating oil, varnish-like deposits on the metal surfaces, and viscosity build-up. Suitable antioxidants include hindered phenols, aromatic amines, and sulfurized alkylphenols, as well as alkali metal and alkaline earth metal salts thereof.

Hindered phenol antioxidants typically contain sec-butyl and/or tert-butyl groups as steric hindering groups. The phenol group may be further substituted with a hydrocarbyl group (typically a straight or branched chain alkyl group) and/or a bridging group attached to a second aryl group. Examples of suitable hindered phenol antioxidants includeIncluding 2, 6-di-tert-butylphenol; 4-methyl-2, 6-di-tert-butylphenol; 4-ethyl-2, 6-di-tert-butylphenol; 4-propyl-2, 6-di-tert-butylphenol; 4-butyl-2, 6-di-tert-butylphenol; and 4-dodecyl-2, 6-di-tert-butylphenol. Other useful hindered phenolic antioxidants include 2, 6-dialkylphenolic propionate derivatives, such as those available from Ciba

L-135, and bisphenolic antioxidants, such as 4,4 '-bis (2, 6-di-tert-butylphenol) and 4, 4' -methylenebis (2, 6-di-tert-butylphenol).

Typical aromatic amine antioxidants have at least two aryl groups directly attached to one amine nitrogen. Typical aromatic amine antioxidants have an alkyl substituent of at least 6 carbon atoms. Specific examples of aromatic amine antioxidants useful herein include 4,4 '-dioctyldiphenylamine, 4' -dinonyldiphenylamine, N-phenyl-1-naphthylamine, N- (4-tert-octylphenyl) -1-naphthylamine, and N- (4-octylphenyl) -1-naphthylamine. The antioxidant may be present at 0.01 to 5 wt.% (e.g., 0.1 to 2 wt.%) of the lubricating oil composition.

Suds suppressor

The lubricating oil compositions disclosed herein may comprise one or more suds suppressors that can disrupt foam in the oil. Non-limiting examples of suitable suds suppressors or suds suppressors include silicone oils or polydimethyl siloxanes, fluorosilicones, alkoxylated aliphatic acids, polyethers (e.g., polyethylene glycol), branched polyvinyl ethers, alkyl acrylate polymers, alkyl methacrylate polymers, polyalkoxyamines, and combinations thereof.

Additional Co-additives

The lubricating oil compositions of the present disclosure may also contain other conventional additives capable of imparting or improving any desired property of the lubricating oil composition in which these additives are dispersed or dissolved. Any additive known to those skilled in the art may be used in the lubricating oil compositions disclosed herein. Mortier et al, "Chemistry and Technology of Lubricants", 2 nd edition, London, Springer, (1996); and Leslie R.Rudnick, "scientific Additives: Chemistry and Applications," New York, Marcel Dekker (2003), both of which are incorporated herein by reference. For example, the lubricating oil composition may incorporate antioxidants, antiwear agents, detergents such as metal detergents, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, suds suppressors, co-solvents, corrosion inhibitors, ashless dispersants, multi-functional agents, dyes, extreme pressure agents, and the like, and mixtures thereof. Various additives are known and commercially available. These additives or their analogous compounds can be used to prepare the lubricating oil compositions of the present disclosure by conventional mixing procedures.

In the preparation of lubricating oil formulations, it is common practice to incorporate additives in the form of 10 to 100 wt.% active ingredient concentrates into hydrocarbon oils such as mineral lubricating oils or other suitable solvents.

Typically, these concentrates may be diluted with from 3 to 100 parts by weight, for example from 5 to 40 parts by weight, of an additive package per part by weight of lubricating oil in forming finished lubricating oils, such as crankcase oils. The purpose of the concentrate is, of course, to make handling of the various materials less difficult and awkward, and to facilitate dissolution or dispersion in the final blend.

When used, each of the above additives is present in a functionally effective amount to impart the desired properties to the lubricating oil. Thus, for example, if the additive is a friction modifier, a functionally effective amount of the friction modifier will be an amount sufficient to impart the desired friction modifying properties to the lubricating oil.

In general, when used, the concentration of each additive in the lubricating oil composition can be from about 0.001 wt.% to about 20 wt.%, from about 0.01 wt.% to about 15 wt.%, or from about 0.1 wt.% to about 10 wt.%, from about 0.005 wt.% to about 5 wt.%, or from about 0.1 wt.% to about 2.5 wt.%, based on the total weight of the lubricating oil composition. In addition, the total amount of additives in the lubricating oil composition can be about 0.001 wt.% to about 20 wt.%, about 0.01 wt.% to about 10 wt.%, or about 0.1 wt.% to about 5 wt.%, based on the total weight of the lubricating oil composition.

Additional base oils of lubricating viscosity

Oils of lubricating viscosity (sometimes referred to as "basestocks" or "base oils") are the major liquid components of lubricants, with additives and possibly other oils mixed therein, for example, to produce the final lubricating oil (or lubricating oil composition). The base oil is useful in making concentrates and in making lubricating oil 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 lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly (1-hexenes), poly (1-octenes), poly (1-decenes)); alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di (2-ethylhexyl) benzene); polyphenols (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof.

The base oil may be derived from fischer-tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons from hydrocarbons containing H₂And CO using a fischer-tropsch catalyst. Such hydrocarbons typically require further processing to be used as base oils. For example, hydrocarbons may be hydroisomerized using processes known to those skilled in the art; hydrocracking and hydroisomerization; dewaxing; or hydroisomerization and dewaxing.

Unrefined, refined and rerefined oils are useful in the lubricating oil compositions of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art, such as distillation, solvent extraction, acid or base extraction, filtration and percolation.

Rerefined oils are obtained by processes similar to those used to obtain refined oils that are already in use. Such rerefined oils, also known as reclaimed or reprocessed oils, are typically additionally processed by techniques requiring approval of spent additives and oil breakdown products.

Thus, the base oils useful in making the lubricating oil compositions of the present invention may be selected from any of the base oils in groups I through V as specified in the American Petroleum Institute (API) base oil interchangeability guide (API Publication 1509). Such base oil groups are summarized in table 1 below.

TABLE 1

(a) Groups I through III are mineral oil basestocks.

(b) Measured according to ASTM D2007.

(c) Measured according to ASTM D2622, ASTM D3120, ASTM D4294 or ASTM D4927.

(d) Measured according to ASTM D2270.

(e) Suitable base oils for use herein are any of the group II, group III, group IV and group V oils and combinations thereof corresponding to the API, preferably group II to group V oils, because of their excellent volatility, stability, viscometric viscosity and cleanliness characteristics.

The oil of lubricating viscosity, also referred to as a base oil, used in the lubricating oil compositions of the present disclosure is typically present in a major amount, for example, in an amount greater than 50 wt.%, preferably greater than about 70 wt.%, more preferably from about 80 to about 99.5 wt.%, most preferably from about 85 to about 98 wt.%, based on the total weight of the composition. As used herein, the expression "base oil" is understood to mean a base stock or blend of base stocks, which is a lubricant component produced by a single manufacturer to the same specifications (independent of the source of the feedstock or the location of the manufacturer); the specifications of the same manufacturer are met; and identified by a unique recipe, product identification number, or both. The base oil used herein can be any presently known or later-discovered oil of lubricating viscosity used to formulate lubricating oil compositions for any and all such applications, for example, engine oils, marine cylinder oils, functional fluids such as hydraulic oils, gear oils, transmission fluids, and the like. In addition, the base oils used herein may optionally contain viscosity index improvers, such as polymerized alkyl methacrylates; olefin copolymers such as ethylene-propylene copolymers or styrene-butadiene copolymers; and the like and mixtures thereof.

Properties of finished lubricating oil

Typically, the lubricating composition has a kinematic viscosity (according to ASTM D445) at 100 ℃ of at most 9.3mm²S, preferably 3.8 to 9.3mm²S, 3.8 to 8.2mm²S, 3.8 to 7.1mm²S, 3.8 to 6.1mm²/s。

Typically, the lubricating composition has a high temperature high shear viscosity ("HTHS") (according to ASTM D4683) at 150 ℃ of 1.3 to 2.6 mPa-s, 1.3 to 2.4 mPa-s, 1.3 to 2.2 mPa-s, 1.3 to 2.0 mPa-s, 1.3 to 1.8 mPa-s.

Typically, the lubricating composition has a high temperature high shear viscosity ("HTHS") at 80 ℃ of less than 4.5 mPas.

Typically, the lubricating composition has a NOACK volatility (according to ASTM D5800B) of 22.0 wt.% or less, 21.0 wt.% or less, 20.0 wt.% or less, 19.0 wt.% or less, 18.0 wt.% or less, 17.0 wt.% or less, 16.0 wt.% or less, 15.0 wt.% or less, 14.5 wt.% or less, 14.0 wt.% or less, 13.5 wt.% or less, 13.0 wt.% or less, 12.5 wt.% or less, 12.0 wt.% or less, 11.5 wt.% or less, 11.0 wt.% or less, 10.5 wt.% or less, 10.0 wt.% or less. Typically, the NOACK volatility is at least 4.0 wt%. In other embodiments, the NOACK volatility is from 15.0 to 2.0 weight percent, from 15.0 to 3.0 weight percent, from 14.5 to 5.0 weight percent, from 14.5 to 7.0 weight percent, from 14.5 to 8.0 weight percent, from 14.5 to 9.0 weight percent.

The following examples are set forth to illustrate embodiments of the disclosure, but are not intended to limit the disclosure to the specific embodiments listed. Unless indicated to the contrary, all parts and percentages are by weight. All numerical values are approximate. When numerical ranges are given, it should be understood that embodiments outside the stated ranges may still fall within the scope of the disclosure. The specific details described in each example should not be construed as essential features of the disclosure.

It will be understood that various modifications may be made to the embodiments disclosed herein. Accordingly, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. For example, the functions described above and those implemented as the best mode for operating the present disclosure are for illustration purposes only. Other arrangements and methods may be implemented by those skilled in the art without departing from the scope and spirit of the present disclosure. In addition, other modifications will occur to those skilled in the art which are within the scope and spirit of the appended claims.

Examples

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

Comparative example 1

A lubricating oil composition was prepared by adding 100 wt.% of bis-2-ethylhexyl azelate base oil. The NOACK of this formulation was 21.7%, and HTHS 80 was 3.61 mPas.

Comparative example 2

By adding 97% by weight of

M-480R (NOF Corp., 2cSt) and 3% by weight, based on the concentrateA borated polyisobutenyl bis-succinimide dispersant, wherein the polyisobutylene has an average molecular weight of about 1300, to provide about 0.019 wt.% boron to the finished oil, to prepare a lubricating oil composition. The NOACK of this formulation was 34.3%, and HTHS 80 was 2.60 mPas.

Comparative example 3

The lubricating oil composition was prepared by adding 99 wt.% bis-2-ethylhexyl azelate and 0.79 wt.% boronated polyisobutenyl bis-succinimide dispersant, based on concentrate, wherein the polyisobutylene had a number average molecular weight of about 1300, providing about 0.005 wt.% boron to the finished oil. The NOACK of this formulation was 21.4%, and HTHS 80 was 3.87 mPas.

Comparative example 4

Lubricating oil compositions were prepared by adding 97 wt.% of group II base oil (KV 100 ═ 3.05, VI ═ 106) and 3 wt.% borated polyisobutenyl bis-succinimide dispersant based on concentrate, with the number average molecular weight of the polyisobutylene being about 1300, providing about 0.019 wt.% boron to the finished oil. The NOACK of this formulation was 36.0%, and HTHS 80 was 3.94 mPas.

Comparative example 5

Lubricating oil compositions were prepared by adding 97 wt.% of a group III base oil (KV 100 ═ 4.19, VI ═ 125) and 3 wt.% of a borated polyisobutenyl bis-succinimide dispersant based on concentrate, wherein the polyisobutylene had a number average molecular weight of about 1300, providing about 0.019 wt.% boron to the finished oil. The NOACK of this formulation was 13.0%, and HTHS 80 was 5.62 mPas.

Comparative example 6

The lubricating oil composition was prepared by adding 97 wt.% diisotridecyl adipate (5cSt) and 3 wt.% boronated polyisobutenyl bis-succinimide dispersant based on concentrate, wherein the average molecular weight of the polyisobutylene was about 1300, providing about 0.019 wt.% boron to the finished oil. The NOACK of this formulation was 3.10%, and HTHS 80 was 7.26 mPas.

Comparative example 7

Lubricating oil compositions were prepared by adding 99 wt.% bis-2-ethylhexyl azelate and 0.37 wt.% HOB boronate detergent, based on the concentrate, to provide about 0.015 wt.% boron to the finished oil. The NOACK of this formulation was 21.0%, and HTHS 80 was 3.71 mPas.

Comparative example 8

Lubricating oil compositions were prepared by adding 99 wt.% bis-2-ethylhexyl azelate and 0.22 wt.% potassium borate dispersion based on the concentrate to provide about 0.015 wt.% boron to the finished oil. The NOACK of this formulation was 20.8%, and HTHS 80 was 3.58 mPas.

Comparative example 9

Lubricating oil compositions were prepared by adding 99 wt.% bis-2-ethylhexyl azelate and 0.62 wt.% boronated glycerol monooleate friction modifier, based on the concentrate, to provide about 0.015 wt.% boron to the finished oil. The NOACK of this formulation was 20.6% and the HTHS 80 was 3.59 mPas.

Example 1

The lubricating oil composition was prepared by adding 98 wt.% bis-2-ethylhexyl azelate base oil and 1.59 wt.% boronated polyisobutenyl bis-succinimide dispersant based on concentrate, wherein the polyisobutylene had a number average molecular weight of about 1300, providing about 0.008 wt.% boron to the finished oil. The NOACK of this formulation was 17.7%, and HTHS 80 was 3.73 mPas.

Example 2

The lubricating oil composition was prepared by adding 97 wt.% bis-2-ethylhexyl azelate base oil and 3 wt.% boronated polyisobutenyl bis-succinimide dispersant, based on concentrate, wherein the polyisobutylene had a number average molecular weight of about 1300, providing about 0.019 wt.% boron to the finished oil. The NOACK of this formulation was 16.4%, and HTHS 80 was 4.01 mPas.

Example 3

A lubricating oil composition was prepared by adding 48 wt.% bis-2-ethylhexyl azelate base oil, 48 wt.% group III base oil (KV 100 ═ 4.19, VI ═ 125), and 3 wt.% boronated polyisobutenyl bis-succinimide dispersant based on concentrate, wherein the polyisobutylene had an average molecular weight of about 1300, providing about 0.019 wt.% boron to the finished oil. The NOACK of this formulation was 15.9%, and HTHS 80 was 4.50 mPas.

Example 4

The lubricating oil composition was prepared by adding 98 wt.% bis-2-ethylhexyl azelate and 2.38 wt.% boronated polyisobutenyl bis-succinimide dispersant, based on concentrate, wherein the polyisobutylene had a number average molecular weight of about 1300, providing about 0.015 wt.% boron to the finished oil. The NOACK of this formulation was 16.7%, and HTHS 80 was 4.05 mPas.

Example 5

The lubricating oil composition was prepared by adding 96 wt.% bis-2-ethylhexyl azelate and 3.97 wt.% boronated polyisobutenyl bis-succinimide dispersant, based on concentrate, wherein the polyisobutylene had a number average molecular weight of about 1300, providing about 0.025 wt.% boron to the finished oil. The NOACK of this formulation was 15.9%, and HTHS 80 was 4.30 mPas.

Example 6

The lubricating oil composition was prepared by adding 96 wt.% bis-2-ethylhexyl azelate and 3 wt.% boronated polyisobutenyl bis-succinimide dispersant, based on concentrate, wherein the polyisobutylene had an average molecular weight of about 1000, providing about 0.018 wt.% boron to the finished oil.

The NOACK of this formulation was 15.0%, and HTHS 80 was 3.85 mPas.

The measured viscosity properties and NOACK volatility properties of the lubricating oils are shown in table 1. The present examples demonstrate the synergistic effect from the combination of a borated dispersant and a low viscosity diester base oil (bis-2-ethylhexyl azelate) that achieves low NOACK volatility while maintaining a low HTHS 80. Example 3 demonstrates that mixtures of diester base oils and conventional base oils also perform well.

In contrast, comparative examples 2 and 4 show that the monoester base oils or conventional base oils alone perform less well in the NOACK test. Although higher viscosity base oils such as those used in comparative examples 5 and 6 achieved low NOACK volatility, the HTHS 80 produced was undesirably high for fuel economy. Comparative examples 7-9 also show that boron sources other than the boronated dispersant are less effective at reducing NOACK volatility.

Claims

1. A lubricating oil composition comprising:

a. a base oil comprising a diester having one of the following structures:

wherein each R is independently C₁-C₂₀A saturated or unsaturated alkyl group, and n is an integer of 1 to 8, wherein the diester has a kinematic viscosity at 100 ℃ of 2.5 to 3.5mm according to ASTM D445²(ii)/s, and a viscosity index according to ASTM D2270 of from 110 to 175; and

2. The lubricating oil composition according to claim 1, wherein the lubricating oil composition has a high shear viscosity of less than 4.5 mPa-s at 80 ℃.

3. The lubricating oil composition of claim 1, further comprising: detergents, anti-wear agents, antioxidants, foam inhibitors, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, co-solvents, corrosion inhibitors, ashless dispersants, multifunctional agents, dyes or extreme pressure agents.

4. The lubricating oil composition according to claim 1, wherein the borated dispersant is a borated polyisobutenyl succinimide or a borated polyalkenyl succinic anhydride.

5. The lubricating oil composition of claim 1, further comprising an additional base oil.

6. A method of reducing evaporation loss in an internal combustion engine, comprising lubricating the engine with a lubricating oil composition comprising:

a. a base oil comprising a diester having one of the following structures:

7. The method of claim 6, wherein the lubricating oil composition has a high shear viscosity of less than 4.5 mPa-s at 80 ℃.

8. The method of claim 6, wherein the lubricating oil composition further comprises: detergents, anti-wear agents, antioxidants, foam inhibitors, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, co-solvents, corrosion inhibitors, ashless dispersants, multifunctional agents, dyes or extreme pressure agents.

9. The method of claim 6, wherein the borated dispersant is a borated polyisobutenyl succinimide or a borated polyalkenyl succinic anhydride.

10. The method of claim 6, wherein the lubricating oil composition further comprises an additional base oil.

11. A method of improving the fuel efficiency of an engine, wherein the method comprises lubricating said engine with a lubricating oil composition comprising:

a. a base oil comprising a diester having one of the following structures:

12. The method of claim 11, wherein the lubricating oil composition has a high shear viscosity of less than 4.5 mPa-s at 80 ℃.

13. The method of claim 11, wherein the lubricating oil composition further comprises: detergents, anti-wear agents, antioxidants, foam inhibitors, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, co-solvents, corrosion inhibitors, ashless dispersants, multifunctional agents, dyes or extreme pressure agents.

14. The method of claim 11, wherein the borated dispersant is a borated polyisobutenyl succinimide or a borated polyalkenyl succinic anhydride.

15. The method of claim 11, wherein the lubricating oil composition further comprises an additional base oil.