ES2658621T3 - Marine Engine Lubrication - Google Patents

Abstract

The use of a detergent system that includes (i) a calcium salt of hydroxybenzoate substituted with overbased alkyl of TBN less than 250, whose alkyl group has 20-28 carbon atoms, in a cylindrical piston marine lubricating oil composition for a medium speed compression marine ignition engine during engine operation, in which the detergent system further comprises (ii) a calcium salt of hydroxybenzoate substituted with overbased alkyl of TBN less than 250, whose alkyl group has 14-18 atoms of carbon, the ratio of% by weight of Ca being from (ii) to (i) greater than one, said use being to improve the asphaltene dispersibility performance of the composition.

Description

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DESCRIPTION

Marine Engine Lubrication Field of the Invention

This invention relates to a method for improving the dispersion of asphaltenes in a cylindrical marine piston engine.

This invention also relates to the use of a detergent system to improve the dispersion of asphaltenes in a cylindrical marine piston engine.

This invention also relates to the use of a detergent system comprising a combination of hydroxybenzoates in a cylindrical marine engine lubricating composition for a four-stroke marine medium-speed compression ignition (diesel) engine to improve dispersion performance. of asphaltenes of the composition.

Background of the invention

Marine cylindrical piston engines generally use heavy fuel oil ('HFO') to operate on the high seas. Heavy fuel oil is the heaviest fraction of petroleum distillate and comprises a complex mixture of molecules that include up to 15% of asphaltenes, which is defined as the fraction of petroleum distillate that is insoluble in an excess of aliphatic hydrocarbon (per heptane example) but which is soluble in aromatic solvents (for example, toluene). Asphaltenes can enter the engine lubricant as contaminants either via the cylinder or fuel pumps and injectors, and asphaltene precipitation can occur next, which manifests as 'black paint' or 'black mud' in the engine . The presence of such carbonaceous deposits on the surface of a piston can act as an insulating layer that can result in the formation of cracks that then propagate through the piston. If a crack passes through the piston, hot combustion gases may enter the crankcase, possibly resulting in a crankcase explosion.

Therefore, it is highly desirable that cylindrical piston engine oils ('TPEO's) prevent or inhibit asphaltene precipitation.

EP-B-1992 678 describes cylindrical piston engine oils containing combinations of overbased alkylsalicylic acid calcium salts to improve wear properties. No mention is made of asphaltene dispersion.

It has now been found that, using certain combinations of hydroxybenzoate in a TPEO, it is possible to achieve improved asphaltene dispersion properties.

Summary of the invention

A first aspect of the invention is the use of a detergent system that includes (i) an overbased alkyl substituted hydroxybenzoate calcium salt of TBN less than 250, whose alkyl group has 20-28 carbon atoms, in an oil composition marine cylindrical piston lubricant for medium speed compression marine ignition engine during engine operation, in which the detergent system further comprises (ii) a calcium salt of hydroxybenzoate substituted with overbased TBN alkyl of less than 250, whose group alkyl has 14-18 carbon atoms, the ratio of% by weight of Ca from (ii) to (i) being greater than one, said use being to improve the asphaltene dispersibility performance of the composition.

A second aspect of the invention is the use of a detergent system that includes (i) an overbased alkyl substituted hydroxybenzoate calcium salt of TBN less than 250, whose alkyl group has 20-28 carbon atoms in a lubricating oil composition cylindrical piston marine for a medium speed compression marine ignition engine during engine operation, driven by heavy fuel oil, and its lubrication by the composition, in which the detergent system further comprises (ii) a calcium salt of TBN-substituted overbased alkyl hydroxybenzoate of less than 250, whose alkyl group has 14-18 carbon atoms, the ratio of weight% of Ca being from (ii) to (i) greater than one, said use being to improve yield of asphaltene dispersion of the composition compared to that of the analogous operation using a detergent system whose ratio of% by weight of Ca is one or less and / or in which (ii) has e a TBN of 250 or greater.

In this specification, the following words or expressions, as long as they are used, have the meanings assigned below:

"active ingredients" or "(a.i.)" refers to additive material that is not diluent or solvent;

"comprising" or any related word specifies the presence of features, stages or integers or components, but does not exclude the presence or addition of one or more features, stages, integers, components or their different groups; the expressions "consists of" or "consists essentially of" or

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cognates, may be included within "comprises" or cognates, in which "it consists essentially of" allows the inclusion of substances that do not materially affect the characteristics of the composition to which it is applied;

"principal amount" means 50% by mass or more than one composition; preferably 40 by mass or more than one composition; more preferably 30% by mass or more than one composition;

"minor amount" means less than 50% by mass of a composition; preferably less than 40% by mass of a composition; more preferably less than 30% by mass of a composition;

"TBN" means total base number as measured by ASTM D2896.

Also in this specification, as long as it is used:

"calcium content" is as measured by ASTM 4951;

"phosphorus content" is as measured by ASTM D5185;

"sulfated ash content" is as measured by ASTM D874;

"sulfur content" is as measured by ASTM D2622;

"KV 100" means kinematic viscosity at 100 ° C as measured by ASTM D445.

In addition, it will be understood that various components used, essential as well as optimal and customary, may react under the conditions of formulation, storage or use and that the invention also provides the product obtainable or obtained as a result of any such reactions.

In addition, it is understood that any of the upper and lower limits of the amount, range and relationship established herein can be combined independently.

Detailed description of the invention

The features of the invention will now be discussed in more detail below.

Lubricating viscosity oil

The cylindrical marine piston lubricating oil composition of the invention comprises a main amount of an oil of lubricating viscosity. That may vary in viscosity from light distilled mineral oils to heavy lubricating oils. Such oil can be called base oil. Generally, the viscosity of the oil varies from 2 to 40 mm2 / s, as measured at 100 ° C. The oil can be a natural or synthetic oil.

Natural oils include animal oils and vegetable oils (for example, castor oil, lard oil); liquid petroleum oils and mineral oils treated with solvent or treated with hydrorefinic acids of the paraffinic, naphthenic and paraffinic-naphthenic types. You can also use lubricating viscosity oils derived from coal or shale

Synthetic lubricating oils include hydrocarbon oils and halosubstituted hydrocarbon oils such as polymerized and interpolymerized olefins (eg, polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly (l-hexenos), poly (l-octenes), poly ( l-deans)); alkylbenzenes (eg, dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di (2-ethylhexyl) benzenes); polyphenyls (for example, biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulphides and derivatives, analogs and their counterparts.

The alkylene oxide polymers and interpolymers and their derivatives in which the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These can be exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and alkyl and aryl ethers of polyoxyalkylene polymers (eg, methyl polyisopropylene glycol ether having a molecular weight of 1,000 or ether polyethylene glycol diphenyl having a molecular weight of 1,000 to 1,500); and its mono- and polycarboxylic esters, for example, acetic acid esters, mixed C3-C8 fatty acid esters and C13 oxo acid diester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises esters of dicarboxylic acids (for example, phthalic acid, succinic acid, alkylsuccinic acids and alkenyl succinic acids, maleic acid, azelaic acid, subic acid, sebacic acid, fumaric acid, adipic acid, dimeric linoleic acid , malonic acid, alkylmalonic acids, alkenylmalonic acids) with a variety of alcohols (for example, butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol). Specific examples of such esters include dibutyl adipate, di (2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, sebacate dieicosyl, the dimer linoleic acid 2-ethylhexyl diester, and the complex ester formed by reacting one mole

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of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C5 to C12 monocarboxylic acids and polyalcohols such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.

Silicon-based oils such as polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxy-silicone oils and silicate oils comprise another useful class of synthetic lubricants; such oils include tetraethyl silicate, tetraisopropyl silicate, tetra- (2-ethylhexyl) silicate, tetra- (4-methyl-2-ethylhexyl) silicate, tetra- (p-tert-butyl-phenyl) silicate, hexa - (4-methyl-2-ethylhexyl) disiloxane, poly (methyl) siloxanes and poly (methylphenyl) siloxanes. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (eg, tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

Unrefined, refined and re-refined oils can be used in lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without other purification treatment. For example, a shale oil obtained directly from retort operations; petroleum oil obtained directly from distillation; or ester oil obtained directly from an esterification and used without further treatment, are unrefined oils. Refined oils are similar to unrefined oils except that the oil is further treated in one or more purification steps to improve one or more properties. Many such purification techniques, such as distillation, solvent extraction, acid or base extraction, filtration and percolation are known to those skilled in the art. Re-refined oils are obtained by procedures similar to those used to provide refined oils but begin with oil that has already been used in service. Such re-refined oils are also known as recovered or reprocessed oils and are often subjected to further processing using techniques to remove spent additives and oil decomposition products.

The publication of the American Petroleum Institute (API) "Engine Oil Licensing and Certification System", Industry Services Department, Fourteenth Edition, December 1996, Addendum 1, December 1998. Classifies base oils as follows:

a) Group I base oils contain less than 90 percent saturated and / or more than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in Table E-1.

b) Group II base oils contain more or equal to 90 percent saturated and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in Table E-1.

c) Group III base oils contain more or equal to 90 percent saturated and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120 using the test methods specified in the Table E-1

d) Group IV base oils are polyalphaolefins (PAO).

e) Group V base oils include all other base oils not included in group I, II, III or IV.

The analytical methods for base oils are tabulated below (table E-1):

 Property

 Testing method

 Saturated

 ASTM D 2007

 Viscosity index

 ASTM D 2270

 Sulfur

 ASTM D 2622

 ASTM D 4294

 ASTM D 4927

 ASTM D 3120

By way of example, the present invention encompasses the base oils of group I, group II, group III and group IV and also the base oils derived from hydrocarbons synthesized by the Fischer-Tropsch process. In the Fischer-Tropsch process, the synthesis gas containing carbon monoxide and hydrogen (or 'syngas') is first generated and then converted into hydrocarbons using a Fischer-Tropsch catalyst. These hydrocarbons typically require additional processing to be useful as a base oil. For example, they can, by methods known in the art, be hydroisomerized; hydrocracking and hydroisomerizing; dewax or

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hydroisomerize and deparaffinate. The synthesis gas can be made, for example, of gas such as natural gas or other gaseous hydrocarbons by steam reforming, when the base material can be referred to as gas-to-liquid base oil ("GTL"); or of biomass gasification, when the base material can be called biomass base oil to liquid ("BTL" or "BMTL"); or of the gasification of coal, when the base material can be called carbon base oil to liquid ("CTL").

Preferably, the lubricating viscosity oil in this invention contains 50% by mass or more of a base material containing 50% by mass or more of a base material containing more or equal to 90% saturated and less than or equal to 0, 03% sulfur or one of its mixtures. Preferably, it contains 60, such as 70, 80 or 90% by mass or more of the defined base material or a mixture thereof. The lubricating viscosity oil may be substantially all of the defined base material or one of its mixtures.

Most preferably, the lubricating viscosity oil in this invention contains 50% by mass or more of a base material that contains 50% by mass or more than a base material that contains less than 90% saturated and more than 0.03% of sulfur or one of its mixtures. Preferably, it contains 60, such as 70, 80 or 90% by mass or more of the defined base material or a mixture thereof. The lubricating viscosity oil may be substantially all of the defined base material or one of its mixtures.

The composition may have a TBN in the range of 20-60, preferably 25-55.

Detergent system

A metallic detergent is an additive based on so-called metal "soaps", that is, metal salts of acidic organic compounds, sometimes referred to as surfactants. They generally comprise a polar head with a long hydrophobic tail. Overbased metal detergents, which comprise neutralized metal detergents as the outer layer of a metal base micelle (eg, carbonate), can be provided including large amounts of metal base by reacting an excess metal base, such as an oxide or hydroxide, with an acid gas such as carbon dioxide.

In the present invention, detergents (i) and (ii) are calcium salts of overbased alkyl substituted hydroxybenzoate, preferably calcium salts of alkyl substituted salicylate.

A salicylate detergent of such a system typically has the structure shown:

image 1

wherein R is a linear alkyl group. There may be more than one R group attached to the benzene ring. The COO- group may be in the other, meta or para position with respect to the hydroxyl group; ortho position is preferred. The R group may be in the ortho, meta or para position with respect to the hydroxyl group.

In (i), R has 20-28, preferably 20-24, carbon atoms. In (ii), R has 14-18 carbon atoms. Each (i) and (ii) may be mixtures.

Salicylic acids are typically prepared by carboxylation, by the Kolbe-Schmitt process, of phenoxides, and in that case, they will generally be obtained (usually in a diluent) mixed with uncarboxylated phenol. Salicylic acids may be sulfurized or unsaturated, and may be chemically modified and / or contain additional substituents. Methods for sulfurizing an alkylsalicylic acid are well known to those skilled in the art and are described, for example, in US 2007/0027057.

The term "overbased" is generally used to describe metal detergents in which the ratio of the number of equivalents of the metal moiety to the number of equivalents of the acid moiety is greater than one. The term "low base content" is used to describe metal detergents in which the ratio of equivalents of metal moiety to acid moiety is greater than 1, and up to about 2.

The basicity of detergents can be expressed as a total base number (TBN). A total base number is the amount of acid needed to neutralize all the basicity of the overbased material. TBN can be measured using standard ASTM D2896 or an equivalent procedure. Detergents, as stated, each have a TBN below 250; for example, the TBN is in the range of 60 to 250, preferably 150 to 250.

The ratio of% by weight of Ca from (ii) to (i) is as claimed greater than one, for example, in the range of 1 to 50,

preferably 1 to 3.

The treatment rate of the detergent system contained in the lubricating oil composition, for example, may be in the range of 1 to 25, preferably 2 to 20, more preferably 5 to 18% by mass.

Co-additives

The lubricating oil composition of the invention may further comprise additives, different and additional to the detergent system. Such additional additives, for example, may include ash-free dispersants, other metal detergents, antiwear agents such as zinc dihydrocarbyldithiophosphates, antioxidants and demulsifiers. In some cases, it is not necessary to provide a dispersant without ashes.

It may be desirable, although not essential, to prepare one or more additive packages or concentrates comprising the additives, whereby the detergent system can be added simultaneously to the base oil to form the lubricating oil composition. The dissolution of the additive package (s) in the lubricating oil can be facilitated by solvents and by mixing accompanied by gentle heating, but this is not essential. The additive package (s) will typically be formulated to contain the additive (s) in appropriate amounts to provide the desired concentration, and / or to perform the desired function in the final formulation when the additive package (s) are combined with a predetermined amount of base oil. Thus, the detergent system, according to the present invention, can be mixed with small amounts of base oil or other compatible solvents together with other desirable additives to form additive packages containing active ingredients in an amount, based on the additive package , for example, from 2.5 to 90, preferably from 5 to 75, most preferably from 8 to 60% by mass of additives in the appropriate proportions, the rest being base oil.

Final formulations such as cylindrical piston engine oil may typically contain 30, preferably 10 to 28, more preferably 12 to 24% by mass of the additive package (s), the remainder being base oil.

The present invention is illustrated, but in no way limited, by the following examples.

Components

The following components were used:

Detergent (ii):

A: a TBN 225 calcium alkylsalicylate detergent and whose alkyl group has 14-18 carbon atoms.

30 B: a TBN 350 calcium alkylsalicylate detergent and whose alkyl group has 14-18 carbon atoms.

C: a TBN 64 calcium alkylsalicylate detergent and whose alkyl group has 14-18 carbon atoms.

Detergent (i): a TBN 223 calcium alkylsalicylate detergent whose alkyl group has 20-24 carbon atoms.

Base oil I: API group I base oil extracted with solvent.

35 HFO: a heavy fuel oil (ISO-F-RMK 380)

Lubricants

The selections of the above components were mixed to give a range of cylindrical piston marine engine lubricants. Some of the lubricants are examples of the invention; others are reference examples for comparison purposes. The compositions of the analyzed lubricants are shown in the tables below under the heading "results". Each lubricant had a TBN of about 40. Each lubricant also contained the same amount of HFO.

essays

Light scattering

The test lubricants were evaluated to determine asphaltene dispersion using light scattering according to the focused beam reflectance method ("FBRM") that predicts asphaltene agglomeration and therefore the formation of 'black mud'.

The FBRM test method was disclosed in the 7th International Symposium on Marine Engineering, Tokyo, October 24-28, 2005, and was published in 'The Benefits of Salicylate Detergents in TPEO Applications with a Variety of

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Base Stocks' in the Conference Proceedings. More details were announced at the CIMAC Congress, Vienna, May 21-24, 2007 and published in "Meeting the Challenge of New Base Fluids for the Lubrication of Medium Speed Marine Engines - An Additive Approach" in the Congress Proceedings In this last document it is described that using the FBRM method it is possible to obtain quantitative results for asphaltene dispersion that predicts the performance of lubricating systems based on base oils that contain more than or less than 90% saturated and more or less than 0.03% sulfur The relative performance predictions obtained from FBRM were confirmed by engine tests on marine diesel engines.

The FBRM probe contains fiber optic cables through which the laser light travels to reach the tip of the probe. At the tip, an optics focuses the laser light to a small point. The optics are rotated so that the focused beam scans a circular path between the probe window and the sample. As the particles flow in front of the window, they intersect the scanning path, giving backscattered light by the individual particles.

The scanning laser beam travels much faster than particles; This means that the particles are effectively stationary. When the focused beam reaches an edge of the particle the amount of backscattered light increases; the amount will decrease when the focused beam reaches the other edge of the particle.

The instrument measures the time of increased backscatter. The backscattering period of a particle is multiplied by the scanning speed and the result is a distance or length of string. A string length is a straight line between any two points on the edge of a particle. This is represented as a distribution of chord lengths, a graph of numbers of chord lengths (particles) measured as a function of the chord length dimensions in micrometers. Since measurements are made in real time, the statistics of a distribution can be calculated and tracked. The FBRM typically measures tens of thousands of strings per second, which results in a robust distribution of string length by number. The method gives an absolute measure of the particle size distribution of asphaltene particles.

The focused beam reflectance probe (FBRM), model Lasentec D600L, was supplied by Mettler Toledo, Leicester, United Kingdom. The instrument was used in a configuration to give a particle size resolution of 1 | jm to 1 mm. FBRM data can be presented in several ways. Studies have suggested that average counts per second can be used as a quantitative determination of asphaltene dispersion. This value is a function of both the average size and the agglomerate level. In this application, the average count rate (over the entire size range) was monitored using a measurement time of 1 second per sample.

The test lubricant formulations were heated to 60 ° C and stirred at 400 rpm; When the temperature reached 60 ° C, the FBRM probe was inserted into the sample. A heavy fuel oil aliquot (10% weight / weight) was introduced into the lubricant formulation with stirring using a four-blade stirrer (at 400 rpm). A value for the average counts per second was taken when the counting rate had reached an equilibrium value (typically after 30 minutes).

Results

Light scattering

The results of the FBRM assays are summarized in Table 1 below, in which the lower particle count indicates better performance.

Example 1 is an example of the invention and Examples A-F are comparison examples.

Results

 Example

 C14-18 alkyl salicylate (225) (ii) A C14-18 alkyl salicylate (350) (ii) B C14-18 alkyl salicylate (64) (ii) C C20-24 alkyl salicylate ( 223) (i) Ca ratio of (ii) to (i) Lasentec count

 one

 10.00 - - 7.90 1.28 40.1

 TO

 - 8.40 - 5.00 2.65 377.7

 B

 - 6.00 - 8.50 1.11 333.8

 C

 - 3.00 - 13.00 0.36 700.2

 D

 - - - 17.94 - 243.4

 AND

 5.00 8.30 - - - 1,037.6

 F

 - 9.80 10.00 - - 187.8

The numbers in brackets after salicylate are TBN's.

As shown above, the minimum Lasentec count is achieved with the use of example 1 which is of the invention. (The lower particle count indicates better performance).

Claims (8)

5 10 fifteen twenty 25 1. The use of a detergent system that includes (i) a calcium salt of hydroxybenzoate substituted with overbased alkyl of TBN less than 250, whose alkyl group has 20-28 carbon atoms, in a cylindrical piston marine lubricating oil composition for a medium speed compression marine ignition engine during engine operation, in which the detergent system further comprises (ii) a calcium salt of hydroxybenzoate substituted with overbased alkyl of TBN less than 250, whose alkyl group has 14- 18 carbon atoms, the ratio of% by weight of Ca from (ii) to (i) being greater than one, said use being to improve the asphaltene dispersibility performance of the composition. 2. The use of claim 1, wherein the hydroxybenzoates, (i) and (ii), are each salicylates. 3. The use of claims 1 or 2, wherein the alkyl group (s) of (i) has (20) 20-24 carbon atoms. 4. The use of any of claims 1-3, wherein the composition has a TBN in the range 2060, preferably 25-55. 5. The use of any one of claims 1-4, wherein the weight ratio of Ca is in the range of 1 to 50, preferably 1 to 3. 6. The use of any one of claims 1-5, wherein the composition comprises an oil of a lubricating viscosity, in a main amount, containing 50% by mass or more than a base oil containing less than 90% of saturated and / or more than 0.03 percent sulfur. 7. The use of any one of claims 1-5, wherein the composition comprises an oil of a lubricating viscosity, in a principal amount, containing 50% by mass or more than a base oil containing more than or equal to at 90% saturated and less than or equal to 0.03% sulfur. 8. The use of a detergent system that includes (i) a calcium salt of hydroxybenzoate substituted with overbased alkyl of TBN less than 250, whose alkyl group has 20-28 carbon atoms, in a cylindrical piston marine lubricating oil composition for a medium speed compression marine ignition engine during engine operation, in which the detergent system further comprises (ii) a calcium salt of hydroxybenzoate substituted with overbased alkyl of TBN less than 250, whose alkyl group has 14- 18 carbon atoms, the ratio of% by weight of Ca from (ii) to (i) being greater than one, said use being to improve the asphaltene dispersibility performance of the composition.