JP4803740B2 - Lubricating composition containing sulfonate and phenate - Google Patents

Description

(Field of Invention)
The present invention relates to a novel detergent composition comprising: (a) at least 3% by weight of an overbased sulfonate detergent, wherein the overbased sulfonate detergent is from 12.5: 1 to 40: (B) at least 1.5% by weight of a sulfur-containing phenate detergent, the sulfur-containing phenate detergent having a metal ratio of 3 or less; and (c) a lubricating viscosity oil. Here, the sulfur-containing phenate contains an oligomer of hydrocarbylphenol, and at least 50% by weight of the oligomer is in the form of a tetramer or higher order oligomer. The invention further relates to the use of the novel detergent composition in marine diesel cylinder lubricants.

(Background of the Invention)
In order to reduce wear and improve cleanliness, it is known to add various additives to oils of lubricating viscosity for diesel or gasoline engines. In diesel engines, oils of lubricating viscosity are used especially to reduce wear on cylinder liners and piston rings. In many cases, the operating temperature and pressure of the engine is sufficient to break the oily film of lubricating viscosity on the inner wall of the cylinder. As a result of this, the cylinders were excessively worn and engine cleanliness was reduced due to deposits.

  U.S. Patent No. 6,099,056 (Dunn) discloses the use of a marine diesel engine lubricant composition, the marine diesel engine lubricant composition comprising: (a) an overbased having a TBN of at least 300. Metal detergents and / or metal detergents other than (b) component (a) (but do not contain small amounts of extreme pressure additives if detergent (b) is present in the composition) And (c) an ashless antiwear additive; and (d) an oil of lubricating viscosity.

  U.S. Patent No. 6,099,028 (Carey et al.) Describes a diesel cylinder with improved cleanliness and load carrying performance by using an additive package containing at least one detergent, antioxidant, antiwear agent and dispersant. Oil is disclosed. The detergent component contains at least one of overbased phenate, phenylate, salicylate or sulfonate.

  Patent Document 3 (Katafuchi) describes (a) at least one of overbased sulfonate, overbased phenate and overbased salicylate; and (b) a lubricating oil composition for diesel engines containing a bis-type succinimide compound. Is disclosed.

  U.S. Patent No. 5,677,086 (Nagamatsu) discloses a marine diesel lubricating oil composition containing an overbased alkyl sulfonate detergent and an overbased sulfur treated alkyl phenate detergent. The overbased sulfur treated alkyl phenate has a TBN of 110 or greater.

  Patent document 5 is disclosing the marine diesel lubricating oil composition containing the polyalkylene succinimide compound for improving abrasion resistance. The lubricating oil composition may further contain up to 6% of at least one highly overbased detergent, the detergent comprising an alkyl phenate or alkenyl phenate, an alkyl phenate-carboxylate or an alkenyl phenate- Selected from carboxylates, alkyl aromatic sulfonates or alkenyl aromatic sulfonates; and mixtures thereof.

  U.S. Patent No. 6,099,077 discloses a lubricating oil composition containing a novel succinimide compound and at least one detergent, the detergent being selected from alkaline earth metal overbased sulfonates, phenates and salicylates. The

U.S. Patent No. 6,057,031 discloses a marine diesel engine using a corrosion inhibitor detergent-dispersant additive combination, the combination comprising: (a) a weakly basic or neutral alkali metal sulfonate. And (b) a medium or high basic alkali metal sulfonate, phenolate or phenolate sulfide, wherein the ratio of sulfonate groups to phenol groups is 1: 3.6 to 4.4; c) Succinimide ashless detergent.
US Pat. No. 6,277,794 US Pat. No. 6,339,051 US Pat. No. 6,376,434 US Pat. No. 6,551,965 UK Patent Application Publication No. 2,328,217 European Patent Application Publication No. 1,086,960 East German Patent No. 298519

  It would be desirable to have a composition with clean properties. The present invention provides a composition having cleaning properties.

  It would be desirable to have a composition that can reduce cylinder wear and reduce deposits. The present invention provides a composition that can reduce cylinder wear and reduce deposits.

(Summary of the Invention)
The present invention provides a composition comprising:
(A) at least 3% by weight of an overbased sulfonate detergent, wherein the overbased sulfonate detergent has a metal ratio of about 12.5: 1 to about 40: 1;
(B) at least 1.5 wt% sulfur-containing phenate detergent, wherein the sulfur-containing phenate detergent has a metal ratio of 3 or less; and (c) an oil of lubricating viscosity;
Here, the sulfur-containing phenate contains an oligomer of hydrocarbylphenol, and at least 50% by weight of the oligomer is in the form of a tetramer or higher order oligomer.

The present invention further provides a process for preparing a lubricating oil composition, the method comprising the steps of mixing:
(A) at least 3% by weight of an overbased sulfonate detergent, wherein the overbased sulfonate detergent has a metal ratio of about 12.5: 1 to about 40: 1;
(B) at least 1.5 wt% sulfur-containing phenate detergent, wherein the sulfur-containing phenate detergent has a metal ratio of 3 or less; and (c) an oil of lubricating viscosity;
Here, the sulfur-containing phenate contains an oligomer of hydrocarbylphenol, and at least 50% by weight of the oligomer is in the form of a tetramer or higher order oligomer.

  The present invention further provides a method of lubricating an internal combustion engine, the method comprising supplying the internal combustion engine with a lubricant containing the composition described herein.

  The present invention further provides a lubricating oil composition having cleaning properties. The present invention further provides compositions that can reduce cylinder wear and reduce deposits.

(Detailed description of the invention)
As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it means a group having a carbon atom bonded directly to the rest of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include the following:
Hydrocarbon substituents, ie aliphatic substituents (eg alkyl or alkenyl), alicyclic substituents (eg cycloalkyl, cycloalkenyl), and aromatic substituted aromatic substituents, aliphatic substituted Aromatic and alicyclic substituted aromatic substituents and cyclic substituents. Here, the ring is completed via other parts of the molecule (eg, two substituents together form a ring);
Substituted hydrocarbon substituents are, ie, substituent-containing non-hydrocarbon groups that do not change the main hydrocarbon character of the substituent (eg, halo (particularly chloro and fluoro), in the context of the present invention. ), Hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);
Hetero substituents, ie, groups that have non-carbon atoms present in the ring or chain while having predominantly hydrocarbon character within the context of the present invention, but otherwise consist of carbon atoms. It is. Heteroatoms include sulfur, oxygen, nitrogen and include substituents such as pyridyl, furyl, thienyl and imidazolyl. Generally, in this hydrocarbyl group, there are no more than 2 non-hydrocarbon substituents, preferably no more than 1 non-hydrocarbon substituent, for each 10 carbon atoms. Typically, there are no such non-hydrocarbon substituents in the hydrocarbyl group.

The present invention provides a composition comprising:
(A) at least 3% by weight of an overbased sulfonate detergent, wherein the overbased sulfonate detergent has a metal ratio of about 12.5: 1 to about 40: 1;
(B) at least 1.5 wt% sulfur-containing phenate detergent, wherein the sulfur-containing phenate detergent has a metal ratio of 3 or less; and (c) an oil of lubricating viscosity;
Here, the sulfur-containing phenate contains an oligomer of hydrocarbylphenol, and at least 50% by weight of the oligomer is in the form of a tetramer or higher order oligomer.

  The total amount of (a) and (b) is 4.5% to 35%, preferably 6.5% to 32%, more preferably 9% to 30% by weight of the lubricating oil composition. %, Even more preferably in the range of 12% to 28% by weight. The amount of properties of component (a) and component (b) is preferably such that component (a) is at least 50% of the total amount of base number (TBN) supplied by detergents (a) and (b), preferably Is present such that it can deliver at least 55%, more preferably at least 60%, even more preferably at least 65%, even more preferably at least 70%. In one embodiment, the weight percent of component (a) is about 94.7 weight percent and component (b) is about 5.3 weight percent. In one embodiment, the amount of component (a) is about 75% by weight and component (b) is about 25% by weight.

  In one embodiment, the weight percent ratio of overbased sulfonate to sulfur-containing phenate detergent is 30: 1 to 0.85: 1, preferably 25: 1 to 0.9: 1, and even more preferably It can be 20: 1 to 0.95: 1.

(Overbased sulfonate detergent)
The sulfonate detergent of this composition can be represented by the following formula:

Wherein each R ¹ is independently alkyl, cycloalkyl, aryl, acyl, or 6 to 40, preferably 8 to 25, and even more preferably 9 to 20 carbon atoms. Other hydrocarbyl groups having; A can separately be a cyclic or acyclic hydrocarbon group; M is hydrogen, the valence of a metal ion, an ammonium ion, and mixtures thereof; and k Is an integer between 0 and 5, for example 0, 1, 2, 3, 4, 5 or a mixture thereof. Preferably k is between 1 and 3, more preferably 1 or 2, even more preferably 1. Preferably, the hydrogen is less than 30% of the available M entity, preferably less than 20%, even more preferably less than 10%, even more preferably less than 5%.

In one embodiment, k is 1 and R ¹ is a branched alkyl having 6 to 40 carbon atoms. In one embodiment, k is 1 and R ¹ is a straight chain alkyl group having 6 to 40 carbon atoms.

  The most preferred sulfonate components are calcium polypropene benzene sulfonate and calcium monoalkylbenzene sulfonate and calcium dialkylbenzene sulfonate, where these alkyl groups have at least 10 carbons, such as 11, 12, 13, Contains 14 or 15 carbon atoms.

  When M is the valence of a metal ion, the metal can be monovalent, divalent, trivalent or a mixture of such metals. When monovalent, the metal M can be an alkali metal, preferably lithium, sodium or potassium; more preferably potassium, which can be used alone or in combination with other metals. . When divalent, the metal M is an alkaline earth metal, preferably magnesium, calcium, barium or a mixture of such metals, more preferably calcium, which may be alone or other Can be used in combination with metal. When trivalent, the metal M can be aluminum, which can be used alone or in combination with other metals. In one embodiment, the metal is an alkaline earth metal. In one embodiment, the metal is calcium.

  When A is a cyclic hydrocarbon group, suitable groups include phenyl or fused bicyclic groups such as naphthalene, indenyl, indanyl, bicyclopentadienyl and mixtures thereof. A can be a fused bicyclic ring, but is preferably a benzene ring.

  When A is an acyclic hydrocarbon group, the carbon chain can be straight or branched, but a straight chain is preferred. Suitable groups include those of carboxylic acids containing 7 to 30, preferably 7 to 20, more preferably 8 to 20, and even more preferably 8 to 15 carbon atoms. Derivatives. Furthermore, the chain can be saturated or unsaturated, but saturation is preferred.

  Typically, the overbased sulfonate detergent has a TBN (total base number) of at least 400, preferably at least 425, more preferably at least 450, even more preferably at least 475. In one embodiment, the overbased sulfonate detergent has a TBN of 500.

(Overbased sulfonate detergent)
This sulfonate detergent is overbased. Overbased materials, separately referred to as overbased salts or superbased salts, are generally single phase, homogeneous Newtonian systems, which are specific acidic organic compounds that react with the metal and the metal. According to the stoichiometry of the above, characterized by an excess metal content than the metal content present to neutralize. These overbased materials are prepared by reacting an acidic material (typically an inorganic or lower carboxylic acid, preferably carbon dioxide) with a mixture containing: acidic organic compound A reaction medium comprising at least one organic solvent, and a promoter (eg a phenol or alcohol mixture). The mixture of alcohols typically contains methanol and at least one alcohol having 2 to 7 carbon atoms and can contain 50 to 60 mole percent methanol. This acidic material usually has a sufficient number of carbon atoms to provide a certain degree of solubility in oil. The excess metal amount is usually expressed as a substrate: metal ratio. The term “substrate: metal ratio” is the ratio of the total equivalent of metal to the equivalent of this substrate. The overbased sulfonate detergent is typically 12.5: 1 to about 40: 1, preferably 13.5: 1 to about 40: 1, more preferably 14.5: 1 to about 40. 1, even more preferably 15.5: 1 to about 40: 1, and even more preferably 16.5: 1 to about 40: 1. Furthermore, the overbased detergent preferably has a low process viscosity and a low final viscosity.

A sulfonate detergent having a TBN of 500 and its preparation are disclosed in US Pat. No. 5,792,732. In Example 2, 500 TBN all linear alkylbenzene sulfonate was prepared in Witco Corp. in n-heptane and methanol. It is prepared by reacting an alkylbenzene sulfonate made with Ca (OH) ₂ and CaO and bubbling CO ₂ . In the aforementioned patent (column 5), a 500 TBN overbased sulfonate containing a highly branched alkylbenzene sulfonate is available as Petronate® C-500 as Witco Corp. Available from Another method of preparing high metal ratio overbased sulfonate detergents is disclosed in US Pat. No. 6,444,625 (see, eg, column 3, bottom). The latter process, providing a sulfonic acid to a reactor, adding a lime reactant for neutralization and overbasing, adding a lower aliphatic C ₁ -C ₄ alcohol and a hydrocarbon solvent, and the process mixture Carbonic acid with carbon dioxide, in the process, the exotherm of the reaction is maintained between 27 ° C and 57 ° C. Alternatively, high metal ratio detergents can be prepared by multiple additions of lime reactants and carbon dioxide, using short chain alcohols with or without hydrocarbon solvents, if desired. For example, the steps of adding lime and carbon dioxide and removing volatile materials can be repeated. The overbased sulfonate detergents of the present invention can be used alone or in combination with other overbased sulfonates.

(Sulfur-containing phenate detergent)
The sulfur-containing phenate detergent of this composition can be represented by the following formula:

Where the number y of sulfur atoms may range from 1 to 8, preferably from 1 to 6, even more preferably from 1 to 4; R ² may be hydrogen or a hydrocarbyl group; Hydrogen or hydrogen terminated (S) _y- linked, ionic or non-phenolic hydrocarbyl group; and M is as described above.

  The monomer units of structure (II) are themselves combined x times in such a way as to form oligomers of hydrocarbylphenol. When x is equal to 0, 1, 2, 3 and 4, oligomers are described as dimers, trimers, tetramers, pentamers and hexamers. Typically, the number of oligomers represented by x is 0-10, preferably 1-9, more preferably 1-8, even more preferably 2-6, even more preferably 2-5. Range. If the concentration is greater than about 0.1 wt%, preferably greater than about 1 wt%, even more preferably greater than about 2 wt%, typically the oligomer is present in a substantial amount. Yes. If the concentration is less than 0.1% by weight, the oligomer is typically present in trace amounts, for example, oligomers having 11 or more repeating units may be present. Generally, in at least 50% of these molecules, x is 2 or greater. This overall sulfur-containing phenate detergent preferably contains less than 20% by weight dimer structure.

  The sulfur-containing phenate detergent contains an oligomer of hydrocarbyl phenol, and at least 50% by weight of the oligomer is in the form of a tetramer or higher order oligomer. Preferably, the tetramer or higher order oligomer is in an amount of at least 52 wt%, more preferably at least 54 wt%, even more preferably at least 56 wt%, even more preferably at least 58 wt%. ,Existing.

  The sulfur-containing phenate detergent preferably contains less than 20 wt% hydrocarbyl phenol dimer, preferably less than 18 wt%, more preferably less than 16 wt%, even more preferably less than 14 wt%.

  The sulfur-containing phenate detergent, except for the metals M and any carbonates of M, is 45% to 95%, preferably 50% to 85%, even more preferably, of the sulfur-containing phenate detergent. , Containing substrate levels ranging from 55% to 75% by weight. “Substrate” means an anionic moiety of structure II or a similar structure. The substrate level is calculated excluding any contribution of diluent oil to this detergent.

In Structure II, each R ² is hydrogen or 4 to 80, preferably 6 to 45, more preferably 8 to 20, and even more preferably 9 to 14 carbon atoms. It may be a hydrocarbyl group containing The number (w) of R ² substituents other than hydrogen on each aromatic ring may range from 0 to 4, more preferably from 1 to 3, and even more preferably from 1 to 2. If two or more hydrocarbyl groups are present, they may be the same or different; and the minimum total number of carbon atoms present in the hydrocarbyl substituent on all rings is oil soluble. In order to guarantee, it can be 8, or preferably 9 ,. Preferred components contain 4 alkyl groups having between 9 and 14 carbon atoms (eg, 9, 10, 11, 12, 13, 14 and mixtures thereof) 4 -Alkylated phenols. These 4-alkylated phenols are typically in the 2-position and contain sulfur.

  Typically, the sulfur-containing phenate detergent has a TBN in the range of 30 to 220, preferably 40 to 205, more preferably 50 to 190, and even more preferably 70 to 175. In one embodiment, the sulfur-containing phenate detergent has a TBN of 150. This sulfur-containing phenate detergent can be used alone or in combination with other sulfur-containing phenate detergents.

  The sulfur-containing phenate detergent is typically 3 or less, preferably 2.7 or less, more preferably 2.5 or less, even more preferably 2.3 or less, even more preferably 2. It has a metal ratio of 1 or less.

  The sulfur-containing phenate further contains hydrocarbylphenol oligomers, at least 50% by weight of such oligomers being in the form of tetramers or higher oligomers. Suitable examples of calcium alkylphenol sulfide detergents are commercially available from The Lubrizol Corporation.

(Oil with lubricating viscosity)
The present invention further contains an oil having a lubricating viscosity. These oils include natural and synthetic oils, hydrocracking, hydrogenation, oils derived from hydrofinishing, unrefined oils, refined and rerefined oils, and mixtures thereof.

  Unrefined oil is oil obtained directly from natural or synthetic raw materials without further purification treatment (or almost no purification treatment).

  Refined oils are similar to unrefined oils, except that they have been further processed in one or more purification stages to improve one or more properties. Purification techniques are known in the art and include solvent extraction, secondary distillation, acid or base extraction, filtration, permeation and the like.

  Rerefined oils are also known as reclaimed oils or reprocessed oils, and are often further processed by methods related to removing spent additives and oil breakdown products.

  Natural oils useful in producing the lubricants of the present invention include animal and vegetable oils (eg, castor oil, lard oil), mineral lubricating oils (eg, liquid petroleum oils, and paraffinic, naphthenic or Mixed paraffin-naphthenic type and solvent-treated mineral or acid-treated mineral lubricants, oils derived from coal or shale or mixtures thereof).

  Synthetic lubricating oils are useful, including hydrocarbon oils such as polymerized olefins and interpolymerized olefins (eg, polybutylene, polypropylene, propylene-isobutylene copolymers); poly (1-hexene) , Poly (1-octene), poly (1-decene) and mixtures thereof; alkylbenzenes (eg, dodecylbenzene, tetradecylbenzene, dinonylbenzene, di- (2-ethylhexyl) -benzene, etc.); polyphenyls (eg, , Biphenyl, terphenyl, alkylated polyphenyl); alkylated diphenyl ethers and alkylated diphenyl sulfides, and their derivatives, analogs and homologues, or mixtures thereof.

  Other synthetic lubricating oils include, but are not limited to, liquid esters of phosphorus-containing acids (eg, tricresyl phosphate, trioctyl phosphate and diethyl ester of decanophosphonic acid), polymerized tetrahydrofuran, and the like. Synthetic oils can be produced by a Fischer-Tropsch reaction, and can typically be hydroisomerized Fischer-Tropsch hydrocarbons or waxes.

  Oils of lubricating viscosity can also be defined as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The five base oil groups are as follows: Group I (sulfur content> 0.03% by weight, and / or <90% by weight saturates, viscosity index 80-120); Group II (sulfur content) ≦ 0.03% by weight, and ≧ 90% by weight saturates, viscosity index 80-120); Group III (sulfur content ≦ 0.03% by weight, and ≧ 90% by weight saturates, viscosity index ≧ 120) Group IV (all polyalphaolefins (PAO)); and Group V (all others not included in Groups I, II, III or IV). This oil of lubricating viscosity contains API Group I, Group II, Group III, Group IV, Group V and mixtures thereof. Preferably, the oil of lubricating viscosity is an API Group I, Group II, Group III, Group IV oil and mixtures thereof. More preferably, the oil of lubricating viscosity is an API Group I, Group II, Group III oil or mixtures thereof.

  The oil having a lubricating viscosity is typically 55 to 99.9% by weight of the lubricating oil composition, preferably 61 to 98.9% by weight, more preferably 65 to 96.8% by weight, Even more preferably, it is present at 67-94% by weight.

(Other performance additives)
Optionally, the lubricating oil composition may contain at least one other performance additive (other than components (a) to (c)) selected from the group consisting of: metal inert Agent, detergent, dispersant, antioxidant, antiwear agent, corrosion inhibitor, anti-scuffing agent, extreme pressure agent, antifoaming agent, demulsifier, friction modifier, viscosity modifier, pour point depressant and the like Mixture of. Typically, a fully formulated lubricating oil will contain one or more of these performance additives.

  The total amount combined with other performance additives is 0-10% by weight of this lubricating oil composition, preferably 0.1-7% by weight, more preferably 0.2-5% by weight, even more preferably. 1 to 5% by weight.

(Metal deactivator)
Metal deactivators can be used to neutralize the catalytic effects of metals that promote oxidation in lubricating oils. Examples of metal deactivators include derivatives of benzotriazole, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole, 2-alkyldithiobenzothiazole, 2- (N, N-dialkyl-dithio Carbamoyl) benzothiazole, 2,5-bis (alkyl-dithio) -1,3,4-thiadiazole, 2,5-bis (N, N-dialkyldithiocarbamoyl) -1,3,4-thiadiazole, 2-alkyl Dithio-5-mercaptothiadiazole and mixtures thereof.

  Preferably, the metal deactivator is a hydrocarbyl substituted benzotriazole compound. These benzotriazole compounds can contain one or more hydrocarbyl substituents at one or more of the following ring positions: 1 position or 2 position or 4 position or 5 position or 6 position or 7 position . The hydrocarbyl group contains 1 to 30, preferably 1 to 15, preferably 1 to 7 carbon atoms. Preferably, the metal deactivator is 5-methylbenzotriazole (tolyltriazole). This metal deactivator can be used alone or in combination with other metal deactivators.

(Dispersant)
Because dispersants often do not contain ash-forming metals prior to mixing with the lubricating oil composition, and because they do not contribute to any ash-forming metal when added to lubricants and polymeric dispersants, Known as an ashless dispersant. Ashless type dispersants are characterized by polar groups attached to relatively high molecular weight hydrocarbon chains. Exemplary ashless dispersants include N-substituted long chain alkenyl succinimides. Examples of N-substituted long chain alkenyl succinimides include polyisobutylene succinimide having a number average molecular weight in the range of 350 to 5000, preferably in the range of 500 to 3000. Succinimide dispersants and their preparation are disclosed, for example, in US Pat. No. 4,234,435.

  In one embodiment, the present invention further comprises at least one dispersant derived from polyisobutylene succinimide, which has a number average molecular weight in the range of 350-5000, preferably 500-3000. . This polyisobutylene succinimide can be used alone or in combination with other dispersants.

  In one embodiment, the present invention further contains at least one dispersant derived from polyisobutylene, an amine and zinc oxide to form a polyisobutylene succinimide complex with zinc. The polyisobutylene succinimide complex with zinc can be used alone or in combination.

  Another type of ashless dispersant is Mannich base. Mannich dispersants are the reaction products of alkylphenols with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). The alkyl group contains at least 30 carbon atoms.

  The dispersant can also be a conventional method post-treated by reaction with various optional reagents. These include urea, thiourea, dimercaptothiadiazole, carbon disulfide, aldehyde, ketone, carboxylic acid, hydrocarbon-substituted succinic anhydride, maleic anhydride, nitrile, epoxide, boron compounds and phosphorus compounds.

(Cleaning agent)
Detergents are known in addition to those mentioned above as components (a) and (b), which include alkali metals, alkaline earth metals and transition metals and one or more hydrocarbyl sulfonic acids, Neutral or overbased Newtonian or non-Newtonian properties with carboxylic acids, phosphorus-containing acids, monothiophosphoric acids and / or dithiophosphoric acids, alkylphenols, sulfur-coupled alkylphenol compounds, salixarates, saligenins or mixtures thereof Can be mentioned. Commonly used metals include sodium, potassium, calcium, magnesium, lithium or mixtures thereof. The most commonly used metals include sodium, magnesium, calcium or mixtures thereof. Detergents, particularly overbased detergents and their preparation are disclosed in US Pat. No. 3,629,109.

(Antiwear agent)
The lubricating oil composition may further contain an antiwear agent. Useful antiwear agents include zinc hydrocarbyl dithiophosphate, phosphate esters or salts thereof; phosphites; and phosphorus-containing carboxylic esters, ethers and amides, or mixtures thereof. Examples of suitable hydrocarbyl dithiophosphate zinc compounds include zinc isopropylmethylamyl dithiophosphate, zinc isopropyl isooctyl dithiophosphate, barium di (nonyl) -dithiophosphate, zinc di (cyclohexyl) dithiophosphate, calcium di (hexyl) dithiophosphate, Mention may be made of zinc isobutyl isoamyldithiophosphate, zinc isopropyl n-butyldithiophosphate, primary amyl isobutyldithiophosphate, methyl amyl dithiophosphate, isopropyl 2-ethylhexyl dithiophosphate, and mixtures thereof.

(Antioxidant)
Antioxidants are known antioxidants, including diphenylamine, hindered phenol, molybdenum dithiocarbamate, sulfurized olefins, and mixtures thereof.

  The diphenylamine antioxidant can be represented by the following formula:

Here, R ³ and R ⁴ are hydrocarbyl groups, preferably arylalkyl or alkyl groups. These arylalkyl groups can contain 6 to 20, preferably 6 to 10 carbon atoms. The alkyl group can be linear or branched, preferably linear; the alkyl group is 1-24, preferably 2-18, and even more preferably 4 Contains ˜12 carbon atoms; and z is independently 0, 1, 2, or 3, provided that at least one aromatic ring contains a hydrocarbyl group. Preferred alkylated diphenylamines include octyl diphenylamine, nonyl diphenylamine, bis-octyl diphenylamine and bis-nonyl diphenylamine.

  Sterically hindered phenols can be represented by the following formula:

Wherein R ⁵ and R ⁶ are independently branched or straight chain alkyl containing 1 to 24, preferably 4 to 18, and even more preferably 4 to 12 carbon atoms. And Q is a bridging group linked to hydrogen, hydrocarbyl, or a second aromatic group.

R ⁵ and R ⁶ can be either linear or branched; branched is preferred. Preferably, the phenol is substituted with butyl and contains two t-butyls. Examples of suitable hydrocarbyl groups include 2-ethylhexyl, n-butyl and dodecyl groups. Examples of suitable bridging groups, -CH ₂ - (methylene bridge) and _{-CH 2} OCH 2 - (ether bridge) and the like.

  These sterically hindered crosslinked phenols, when present, can be represented by the following formula:

Where R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² are either linear or branched and are 4 to 18, preferably 4 to 12 carbons. Contains atoms. Preferably, the phenol is substituted with butyl. R ¹³ and R ¹⁴ are independently hydrogen or hydrocarbyl; preferably R ¹³ and R ¹⁴ are arylalkyl or alkyl groups. The alkyl groups of R ¹³ and R ¹⁴ can be straight or branched, with straight chains being preferred. R ¹³ and R ¹⁴ are preferably in the para position. These arylalkyl or alkyl groups typically contain 1 to 15, preferably 1 to 10, more preferably 1 to 5 carbon atoms. Examples of the bridging group Y include —CH ₂ — (methylene bridge) or —CH ₂ OCH ₂ — (ether bridge).

  Examples of methylene bridged sterically hindered phenols include 4,4'-methylene-bis- (6-tert-butyl-o-cresol), 4,4'-methylene-bis- (2-tert- Amyl-o-cresol), 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol) and 4,4'-methylene-bis- (2,6-di-tert-butylphenol). It is done. In one embodiment, the sterically hindered phenol antioxidant is a hindered ester represented by the formula:

Here, R ¹⁵ and R ¹⁶ are linear or branched alkyl groups containing 3 to 22, preferably 3 to 18, more preferably 4 to 12 carbon atoms (these are Can be substituted or unsubstituted). Specific examples of alkyl groups include di-secondary butyl and tri-tertiary butyl. R ¹⁷ can be hydrocarbyl. Suitable examples of R ¹⁷ include 2-ethylhexyl or n-butyl, dodecyl, —CH ₂ CH ₂ COOH and mixtures thereof.

Suitable examples of molybdenum dithiocarbamates that can be used as antioxidants include commercially available materials sold under the following trade names: Vanrube 822 ^™ and Polyvan ^™ A (RT Vanderbilt Co., Ltd. ) And Adeka Sakura-Lube ^™ S-100 and S-165 and S-600 (Asahi Denka Kogyo Co., Ltd.), and mixtures thereof.

  Examples of suitable olefins that can be sulfurized to form an antioxidant include propylene, isobutylene, pentene, hexane, heptene, octane, nonene, decene, undecene, dodecene, undecyl, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, Examples include octadecene, octadecenene, nonodecene, eicosene or mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof, and their dimers, trimers and tetramers are particularly preferred olefins. Alternatively, the olefin can be a Diels-Alder adduct of a diene (eg, 1,3-butadiene) and an unsaturated ester (eg, butyl (meth) acrylate).

  Other types of sulfurized olefins include fatty acids and their esters. These fatty acids are often obtained from vegetable or animal oils; and typically contain from 4 to 22 carbon atoms. Examples of suitable fatty acids and their esters include triglycerides, oleic acid, linoleic acid, palmitoleic acid or mixtures thereof. In many cases, these fatty acids are obtained from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof. In one embodiment, the fatty acid is mixed with an olefin.

(Corrosion inhibitor)
Corrosion inhibitors include amine salts of carboxylic acids (eg octylamine octoate (octylamine salt of octoate)), dodecenyl succinic acid or anhydride and fatty acids (eg oleic acid) and polyamines (eg polyalkylene polyamine ( For example, triethylenetetramine)) and half-esters of alkenyl succinic acid (wherein the alkenyl group contains from 8 to 24 carbon atoms) and an alcohol (eg polyglycol) Can be mentioned.

(Anti-scuffing agent)
The lubricant may also contain anti-scuffing agents. Anti-scuffing agents that reduce adhesive wear are often sulfur-containing compounds. Typically, these sulfur-containing compounds include polysulfides (eg, benzyl disulfide, bis- (chlorobenzyl) disulfide, dibutyl tetrasulfide, di-tertiary butyl polysulfide, sulfurized sperm whale oil, sulfurized methyl ester of oleic acid. , Sulfurized alkylphenol, sulfurized diterpene, sulfurized terpene, sulfurized Diels-Alder adduct, alkylsulfenyl N′N-dialkyldithiocarbamate), reaction product of polyamine and polybasic acid ester, 2,3-dibromopropoxyisobutyric acid Mention may be made of chlorobutyl esters, acetoxymethyl esters of dialkyldithiocarbamic acid and acyloxyalkyl ethers of xanthogenic acid and mixtures thereof.

(Extreme pressure agent)
Extreme pressure (EP) agents that are soluble in the oil include sulfur and chlorosulfur containing EP agents, chlorinated hydrocarbon EP agents and phosphorus EP agents. Examples of such EP agents include chlorinated waxes; organic sulfides and polysulfides (eg, benzyl disulfide, bis- (chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized sperm oil, sulfurized methyl ester of oleic acid, sulfurized alkylphenol, Sulfurized diterpenes, sulfurized terpenes, sulfurized Diels-Alder adducts); phosphosulfurized hydrocarbons (eg, reaction products of phosphorous sulfide with turpentine oil or methyl oleate; phosphorus esters (eg, dihydrophosphite and trihydrocarbons) Dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentyl phenyl phosphite; dipentyl phenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted pheno phosphite )), Metal thiocarbamate (eg, zinc dioctyldithiocarbamate) and barium heptylphenol diacid; amine salts of alkyl and dialkyl phosphates (eg, amine salts of reaction products of dialkyl dithiophosphates and furopylene oxides) And mixtures thereof; and mixtures thereof.

(Anti-foaming agent)
Anti-foaming agents are known and can include organic silicones such as polyacetates, dimethyl silicones, polysiloxanes, polyacrylates or mixtures thereof. Examples of antifoaming agents include polyethyl acrylate, poly 2-ethylhexyl acrylate, polyvinyl acetate, and mixtures thereof.

(Demulsifier)
Demulsifiers are known and include propylene oxide, ethylene oxide, polyoxyalkylene alcohols, alkylamines, amino alcohols, diamines and derivatives of polyamines, which in turn react with ethylene oxide or substituted ethylene oxide, or Of the mixture. Examples of demulsifiers include trialkyl phosphates, polyethylene glycol, polyethylene oxide, polypropylene oxide, (ethylene oxide-propylene oxide) polymers, and mixtures thereof.

(Pour point depressant)
Pour point depressants are known and include maleic anhydride-styrene copolymer esters, polymethacrylates; polyacrylates; polyacrylamides; condensation products of haloparaffin waxes with aromatic compounds; vinyl carboxylate polymers; And terpolymers of dialkyl fumarate, vinyl esters of fatty acids, ethylene-vinyl acetate copolymers, alkylphenol formaldehyde condensation resins, alkyl vinyl ethers and mixtures thereof.

(Friction modifier)
Friction modifiers are known and include fatty amines, esters (especially glycerol esters (eg glycerol monooleate, borated glycerol esters)), fatty phosphites, fatty acid amides, fatty epoxides, boric acid. Mention of chlorinated fatty epoxides, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, sulfurized olefins, fatty imidazolines, condensation products of carboxylic acids with polyalkylene-polyamines, amine salts of alkyl phosphoric acids Can do.

(Viscosity modifier)
Viscosity modifiers are known and are typically polymeric materials, including styrene-butadiene rubber, ethylene-propylene copolymer, polyisobutylene, hydrogenated styrene-isoprene polymer, polymethacrylate, polymethacrylate. Acrylic esters, polyalkyl styrenes, alkenyl aryl conjugated diene copolymers, polyolefins, polyalkyl methacrylates, esters of maleic anhydride-styrene copolymers and mixtures thereof.

(process)
The present invention also includes a process for preparing the composition of the present invention, the process comprising mixing the following:
(A) at least 3% by weight of an overbased sulfonate detergent, wherein the overbased sulfonate detergent has a metal ratio of about 12.5: 1 to about 40: 1;
(B) at least 1.5 wt% sulfur-containing phenate detergent, wherein the sulfur-containing phenate detergent has a metal ratio of 3 or less; and (c) an oil of lubricating viscosity;
Here, the sulfur-containing phenate contains an oligomer of hydrocarbylphenol, and at least 50% by weight of the oligomer is in the form of a tetramer or higher order oligomer.

  The mixing conditions are typically 15 ° C to 130 ° C, preferably 20 ° C to 120 ° C, even more preferably 25 ° C to 110 ° C; and 30 seconds to 48 hours, preferably 2 minutes to 24 ° C. Hours, even more preferably, times ranging from 5 minutes to 16 hours; and 86.4 kPa to 266 kPa (650 mmHg to 2000 mmHg), preferably 91.8 kPa to 200 kPa (690 mmHg to 1500 mmHg), even more preferably The pressure is 1 kPa to 133 kPa (715 mmHg to 1000 mmHg).

  This process includes the step of mixing other performance additives as described above, if desired. This optional performance additive can be added sequentially, separately or as a concentrate.

  If the present invention is in the form of a concentrate (which can be mixed with additional oils, in whole or in part, to form the final lubricant), not only the dispersant but also each of the other ingredients The ratio with the diluent oil is typically 80:20 to 10:90 on a weight basis.

(Industrial use)
The compositions of the present invention are useful as detergents in lubricants for internal combustion engines (eg, diesel fuel engines, gasoline fuel engines, natural gas fuel engines or mixed gasoline / alcohol fuel engines).

  In one embodiment, the present invention provides a method of lubricating an internal combustion engine, the method comprising supplying the internal combustion engine with a lubricant containing the composition described herein. The present invention is suitable for 2-stroke or 4-stroke marine diesel engines, particularly 2-stroke engines. The use of this lubricating oil composition can provide one or more of increased cleanliness, reduced cylinder wear, reduced deposits, and mixtures thereof.

  The following examples illustrate the invention. These examples are not exhaustive and are not to be construed as limiting the scope of the invention.

500 TBN using flanges and clips, overhead stirrer (with paddle) and polytetrafluoroethylene (PTFE) stirrer gland, Dean Stark trap and double surface cooler, flange vessel with mantle / thermocouple temperature control system A sample of sulfonate is prepared, which is covered with glass wool from just above the mantle to just below the cooler. The vessel is charged with 35.1 parts by weight C ₁₆ -C ₂₄ alkyl benzene sulfonic acid and 31.8 parts by weight mineral oil (SN 150) and heated to 30 ° C. The reactor is charged through a port with alcohol (which contains a methanol and isobutanol / amyl alcohol mixture and is present at 11.6 parts by weight). The weight ratio of methanol to isobutanol / amyl alcohol mixture is 1.31. The reactor is charged with 14.9 parts by weight of calcium hydroxide and the mixture is heated to 54 ° C. where carbon dioxide is added to form a carbonated product. The carbonated product is further treated three more times with similar (ie, equal) portions of calcium hydroxide and carbon dioxide. After removing the water by stripping, the addition of alcohol, calcium hydroxide and carbon dioxide is repeated twice. The product is stripped and filtered.

(Reference examples R1 to R7)
(Reference Example 1 (R1))
Exxon ^™ 600N oil (which has 11.9 mm ² s ⁻¹ (cSt) at 100 ° C.) 80 wt% Exxon ^™ 150BS oil (which is 31.7 mm ² s ⁻¹ (cSt at 100 ° C.) The oil having a lubricating viscosity is prepared by blending with 20% by weight. To this oil of lubricating viscosity, 4.6% and 12.9% by weight, respectively, commercially available conventional sulfur-containing phenate detergent ("Type 1") and sulfonate detergent (which contains 500 total bases). Add). This “sulfur-containing phenate detergent (“ Type 1 ”)” has a metal ratio of 8.6: 1. The sulfur-containing phenate oligomer alkylphenol has a dimer form of about 22% by weight, a trimer form of about 23% by weight and a tetramer or higher oligomer form of about 46% by weight.

(Reference Example 2 (R2))
This experimental procedure is the same as the method of Reference Example 1 except that the phenate detergent is a commercially available normal sulfur-containing phenate detergent ("Type 2"). This “sulfur-containing phenate detergent (“ Type 2 ”)” has a metal ratio of 7.7: 1. The sulfur-containing phenate oligomer alkylphenol has a dimer form of about 22% by weight, a trimer form of about 23% by weight and a tetramer or higher oligomer form of about 46% by weight.

(Reference Example 3 (R3))
The experimental procedure is the same as the method of Reference Example 1 except that the phenate detergent is added at 3.08% by weight and the sulfonate is added at 13.33% by weight.

(Reference Example 4 (R4))
The experimental procedure is the same as that of Reference Example 2 except that the phenate detergent is added at 3.08 wt% and the sulfonate is added at 13.33 wt%.

(Reference Example 5 (R5))
This experimental procedure consists in adding a sulfonate detergent package having a total base number of 400 at 7.5% by weight; and adding a commercial phenate detergent having a total base number of 250 at 16% by weight. This is the same as the method of Reference Example 1. In addition, the oil of lubricating viscosity is 1.2% by weight and contains a polyisobutylene succinimide dispersant.

(Reference Example 6 (R6))
This experimental procedure is a reference example, except that sulfonate with a total base number of 400 is added at 8.56 % by weight; and a commercial phenate detergent with a total base number of 250 is added at 7.45 % by weight. This is the same as method 1.

(Reference Example 7 (R7))
This experimental procedure consists of adding a sulfonate having a total base number of 400 at 16 % by weight; and adding a commercial phenate detergent having a total base number of 250 at 1.79 % by weight of Reference Example 1. The method is the same.

( Reference Example 8 (Ex1))
This experimental procedure is the same as the process of Reference Example 1 except that the phenate detergent is a commercial product from The Lubrizol Corporation having a total base number of 150. This phenate detergent has a 1: 1 metal ratio. The alkylphenol of the sulfur-containing phenate oligomer is oligomerized at about 13% by weight in dimer form, about 21% by weight in trimer form and about 60% by weight in tetramer or higher oligomer form.

( Reference Example 9 (Ex2))
This experimental procedure is the same as the process of Reference Example 3, except that the phenate detergent is a commercial product from The Lubrizol Corporation having a total base number of 150.

( Reference Example 10 (Ex3))
This experimental procedure involves adding a sulfonate detergent package having a total base number of 500 at 10.67% by weight; and 5.56% by weight of a phenate detergent commercially available from The Lubrizol Corporation having a total base number of 150. And with the R5 commercial phenate detergent having a total base number of 250 added at 3.33% by weight . In addition, the oil of lubricating viscosity contains a polyisobutylene succinimide dispersant in an amount of 1.2% by weight.

( Reference Example 11 (Ex4))
This experimental procedure is except that sulfonate having a total base number of 500 is added at 9.52% by weight and a commercial phenate detergent from The Lubrizol Corporation having a total base number of 150 is added at 14.93% by weight. Is the same as the process of Reference Example 3. In addition, the oil of lubricating viscosity is 0.6% by weight and contains a polyisobutylene succinimide dispersant.

( Reference Example 12 (Ex5))
This experimental procedure is except that sulfonate having a total base number of 500 is added at 12.66% by weight and commercially available phenate detergent from The Lubrizol Corporation having a total base number of 150 is added at 4.62% by weight. Is the same as the process of Reference Example 3. In addition, the oil of lubricating viscosity contains zinc oxide-polyisobutylene succinimide dispersant in an amount of 0.81% by weight.

( Reference Example 13 (Ex6))
This experimental procedure consists in adding a sulfonate having a total base number of 500 at 12.88% by weight and adding a commercial phenate detergent from The Lubrizol Corporation having a total base number of 150 at 3.85% by weight. Is the same as the process of Reference Example 5.

( Reference Example 14 (Ex7))
This experimental procedure consists of a sulfonate having a total base number of 500 1 3 . Same as the process of Reference Example 5 except that it is added at 33% by weight and a phenate detergent commercially available from The Lubrizol Corporation having a total base number of 150 is added at 2.31% by weight.

( Reference Example 15 (Ex8))
This experimental procedure is except that sulfonate having a total base number of 500 is added at 13.77% by weight and phenate detergent commercially available from The Lubrizol Corporation having a total base number of 150 is added at 0.77% by weight. Is the same as the process of Reference Example 5.

( Comparative Example 1: Pressurized differential scanning calorimetry (PDSC))
Approximately 2.50 mg ± 0.25 mg of sample is placed in a “TA DSC 2920 ^™ Colorimeter”, heated to 215 ° C. at 40 ° C./min and held at 690 kPa. By calculating the length of time that the heated sample oxidizes, the oxidation induction time for the oil of lubricating viscosity is calculated. The results obtained by testing the lubricants of the indicated examples are as follows:

( Comparative Example 2: Panel coker)
Approximately 233 g of sample is placed in a 250 ml Panel Cocker apparatus and heated to 325 ° C. The sample is splashed onto a metal plate for 15 seconds and then baked for 45 seconds. This splashing and baking cycle is continued for about 3 hours. The sample is cooled to room temperature and the amount of deposit remaining on the metal plate is weighed. The results obtained by testing the lubricants of the indicated examples are as follows:

When analyzing the experimental data obtained for the following combinations of reference examples and examples of the present invention, the overbased sulfonate detergent used in combination with the sulfur-containing phenate detergent of the present invention improves the oxidation characteristics of the oil, It is apparent that there is less deposit formation than the combination of overbased sulfonate detergents and other commercially available sulfur-containing phenate detergents: R1, R2 and Ex3; R1, R4 and Ex2; R5 and Ex3 and Ex4. R6 and Ex5 and Ex6; and R7 and Ex7 and Ex8.

  The contents of each reference cited above are incorporated herein by reference. All numerical quantities, reaction conditions, molecular weights, number of carbon atoms, etc. in this description that specify the quantity of a substance are modified by the term “about” unless otherwise stated or otherwise clearly indicated. You can see that Unless otherwise indicated, each chemical or composition referred to herein is considered to be present in its isomers, by-products, derivatives, and other such as would normally be found in commercial grade materials. It should be construed as a commercial grade material that can contain such materials. However, the amount of each chemical component is provided except for solvents or diluent oils that may typically be present in commercial grade materials unless otherwise indicated. It will be appreciated that the upper and lower amounts, ranges and ratios set forth herein may be combined separately. Similarly, the range and amount of each element of the invention can be used in combination with the range or amount of any other element. As used herein, the expression “consisting essentially of” may include substances that do not significantly affect the basic and novel properties of the composition in question.

Claims (16)

Less than:
(A) at least 3 wt% overbased sulfonate detergent having a metal ratio of 12.5: 1 to 40: 1;
(B) at least 1.5 wt% sulfur-containing phenate detergent having a metal ratio of 3 or less; and (c) an oil of lubricating viscosity;
A composition comprising:
Here, the sulfur containing phenate contains oligomers of hydrocarbyl phenol, 50% by weight of the oligomer even without least is in the form of tetramer or higher oligomers,
Composition. The composition of claim 1, wherein the sulfonate detergent has a total base number of at least 400. The composition of claim 1, wherein the sulfonate detergent has a total base number of at least 450. The substrate for the sulfonate detergent is represented by the following formula:
Wherein each R ¹ is independently a hydrocarbyl group having 6 to 40 carbon atoms; A is a cyclic or acyclic hydrocarbon group; M is a metal ion valence Hydrogen, ammonium ions or mixtures thereof; and k is 1-5 .
The composition of claim 1. The composition of claim 1, wherein the sulfonate detergent incorporates a metal ion selected from the group consisting of alkali metals, alkaline earth metals and mixtures thereof. The sulfur-containing phenate detergent is represented by the following formula:
Where the number y of sulfur atoms is 1 to 8; T is hydrogen or hydrogen terminated (S) _y- linked, ionic or non-phenolic hydrocarbyl group sulfur; M is hydrogen, metal ion Valences, ammonium ions and mixtures thereof, provided that hydrogen is present in less than 30% of the M entity; and R ² contains hydrogen or 4 to 80 carbon atoms X is 0-10, with the proviso that at least 50% of x is 2 or greater; w is in the range of 0-3, provided that at least one aromatic ring Contains an R ² substituent and the total number of carbon atoms in the R ² group is at least 8;
The composition of claim 1. The composition of claim 1, wherein the sulfur-containing phenate detergent contains less than 20% by weight of a dimeric structure. Said sulfur-containing phenate detergent contains a group quality levels in the range of 45-95% by weight of the sulfur containing phenate detergent, in which said substrate level excluding any carbonate of the metal M and M, wherein Item 2. The composition according to Item 1. It said sulfur-containing phenate detergent has a total base number of between 30 and 220, the composition of claim 1. 2. The composition of claim 1, wherein the oil of lubricating viscosity comprises an API Group I, Group II, Group III, Group IV oil or mixtures thereof. Furthermore, it contains at least one optional performance additive, and the performance additive is a metal deactivator, detergent, dispersant, antioxidant, antiwear agent, corrosion inhibitor, anti-scuffing agent, pole The composition of claim 1 selected from the group consisting of pressure agents, antifoaming agents, demulsifiers, friction modifiers, viscosity modifiers, pour point depressants and mixtures thereof. A process for preparing a composition comprising the following:
(A ) at least 3% by weight of an overbased sulfonate detergent having a metal ratio of 12.5: 1 to 40: 1;
(B) 3 having the following metal ratios of at least 1.5 wt% sulfur containing phenate detergent; and (c) an oil of lubricating viscosity,
A step of mixing
Here, the sulfur containing phenate contains oligomers of hydrocarbyl phenol, 50% by weight of the oligomer even without least is in the form of tetramer or higher oligomers,
process. In addition, the method further includes the step of adding at least one optional performance additive, the performance additive being a metal deactivator, detergent, dispersant, antioxidant, antiwear agent, corrosion inhibitor, anti-scuffing agent. The process of claim 12 selected from the group consisting of agents, extreme pressure agents, antifoaming agents, demulsifiers, friction modifiers, viscosity modifiers, pour point depressants and mixtures thereof. A method of lubricating an internal combustion engine comprising supplying the internal combustion engine with a lubricant containing the composition of claim 1. The method of claim 14, wherein the internal combustion engine is a marine diesel engine. The method according to claim 15, wherein the internal combustion engine is a two-stroke engine.