JP2022501492A - Fuel composition - Google Patents

Abstract

A fuel composition comprising a base fuel and at least one viscosity index (VI) improving additive, wherein the viscosity index (VI) improving additive provides a fuel composition which is a star-shaped polyisoprene-based polymer. Viscosity index-enhancing additives can be used in fuel compositions to not only improve lubricity, but also to improve power and / or acceleration properties.

Description

The present invention relates to an automobile fuel composition, particularly an automobile fuel composition containing a viscosity index improver (VII) component.

Viscosity index (VI) is a commonly used method for measuring changes in fluid viscosity with temperature. The higher the VI, the smaller the relative change in viscosity with temperature. A VI improver (also called a viscosity modifier) is an additive that increases the viscosity of a fluid over its useful temperature range.

It is known to use a thickening component in fuel compositions to improve acceleration performance. WO2009 / 118302 is an automobile fuel composition for the purpose of improving the acceleration performance of an internal combustion engine into which or is intended to be introduced, or a vehicle powered by such an engine. Describes the use of viscosity index (VI) improving additives.

It is desirable that the performance of the vehicle engine can be further improved by changing the composition and / or characteristics of the fuel introduced into the vehicle engine, rather than making structural or operational changes to the engine itself. It can be expected to provide a simpler, more flexible and more cost effective route to performance optimization.

In particular, one or more other aspects of the fuel composition, such as friction conditioning properties, lubricity, as well as identifying novel viscosity index (VI) improving additives that result in improved power and / or acceleration properties. It would be desirable to improve engine cleanliness, low temperature performance and pumping performance.

US2013 / 0165362 discloses certain linear and star-shaped polymers suitable for use as viscosity index improvers for lubricating oil compositions. However, the use of such polymers in fuel compositions is not disclosed in US2013 / 0165362.

According to the present invention, a fuel composition containing a base fuel and a viscosity index improver is provided, and the viscosity index improver contains a star-shaped polyisoprene-based polymer.

According to a second aspect of the present invention, the use of a viscosity index improver in a fuel composition to provide improved lubricity is provided, the viscosity index improver comprising a star-shaped polyisoprene-based polymer.

A further aspect of the invention provides the use of a viscosity index improver in a fuel composition to provide improved power and / or acceleration properties, the viscosity index improver being a star polyisoprene-based polymer. be.

Surprisingly, the viscosity index improvers described herein can be used in fuel compositions to provide improved lubricity and to provide improved power and / or acceleration properties. Was found.

Therefore, according to yet another aspect of the present invention, a viscosity index (VI) improving additive or a fuel composition containing a viscosity index (VI) improving additive is introduced or is intended to be introduced. A viscosity index (VI) improving additive in a fuel composition for the purpose of improving the output and / or acceleration performance of an internal combustion engine or a vehicle powered by such an engine while at the same time improving the lubricity of the fuel composition. This viscosity index (VI) enhancing additive is a polyisoprene-based star polymer.

Also, the viscosity index improvers used in the fuel compositions herein have improved friction conditioning properties, improved filtration properties, improved viscosity properties, improved low temperature performance, improved pumping performance, especially at low temperatures. It has been found that it can provide one or more of improved pumping performance and no increase in engine fouling.

As used herein, the term "viscosity index (VI) improver" means an additive that increases the viscosity of a fuel over its useful temperature range. The viscosity index improver is also known as a viscosity modifier.

The fuel composition described herein is preferably a diesel fuel composition, and the internal combustion engine described herein is preferably a diesel engine.

"Diesel engine" means a compression ignition internal combustion engine adapted to operate on diesel fuel.

In addition to using the invention to improve engine power and / or acceleration characteristics, the invention can be used to improve the lubricity of fuel compositions. As used herein, the term "lubricity" with respect to fuel means the ability of fuel to reduce friction and / or wear of an internal combustion engine.

Lubrication performance can be assessed by measuring engine wear. Engine wear can be measured by any suitable method. A suitable method for measuring engine wear is the HFRR (High Friction Reciprocating Rig) test ISO12156. In the context of the present invention, "improvement" in lubrication performance includes any degree of improvement. Similarly, the decrease or increase in the measured parameters (eg, the decrease or increase in engine wear provided by the fuel composition) may in some cases include any degree of decrease or increase. In some cases, the increase, decrease, or increase may be compared to the relevant parameters when using the fuel composition prior to incorporating the viscosity index (VI) improving additive. It is intended for use in internal combustion (typically diesel) engines (eg, commercially available) before adding a viscosity index (VI) enhancing additive to the fuel composition. It may be compared to the relevant parameters measured when the same engine is run on the composition.

The present invention adjusts the properties and / or performance and / or effects of the fuel composition, in particular its effect on the lubrication performance of the fuel composition, in order to meet the desired goal, for example, with a viscosity index (VI) enhancing additive. Can include that.

The improvement in lubrication performance may also include at least some relief in the deterioration of lubrication performance due to another cause, in particular another fuel component or additive contained in the fuel composition.

The improvement in lubrication performance may also include at least a partial recovery of lubrication performance that has been reduced for other reasons such as desulfurization, hydrotreating or hydrocracking of diesel and diesel components.

"Acceleration performance" generally includes the responsiveness of the engine to increased throttle, eg, the speed at which it accelerates from any given engine speed. This includes the level of output and / or torque and / or vehicle traction (VTE) produced by the engine at any given speed. Therefore, an improvement in acceleration performance can be evident by an increase in engine power and / or torque and / or VTE at any given speed.

Engine torque can be derived from the force exerted on the dynamometer by the wheels of the vehicle powered by the engine under test. Suitable specialized equipment (eg, Kistler ™ RoaDyn ™) can be used to make measurements directly from the wheels of such vehicles. Engine power can be suitably derived from measured engine torque and engine speed values, as is known in the art. The VTE can be measured, for example, by measuring the force applied to the rollers of the chassis dynamometer by the wheels of the vehicle driven by the engine.

The present invention may be useful for improving the acceleration performance of an internal combustion engine or a vehicle powered by such an engine. Acceleration performance can be assessed by accelerating the engine and monitoring engine speed, power, torque, and / or VTE, air charge pressure, and / or turbocharger speed over time. This evaluation can be suitably performed over a range of engine speeds.

Acceleration performance can also be evaluated by accelerating a vehicle powered by the engine under test, for example from 0 to 100 km / hour, by a driver with suitable experience on the road. In order to correlate changes in acceleration performance with engine speed, the vehicle must be equipped with appropriate measuring instruments such as an engine speedometer.

In general, an improvement in acceleration performance is a reduction in acceleration time and / or one or more of the above effects, such as a faster increase in turbocharger speed, or engine torque or output at any given speed. It can be revealed by an increase in VTE.

In the context of the present invention, "improvement" in acceleration performance includes any degree of improvement. Similarly, the decrease or increase in the measured parameters (eg, the time it takes for the turbocharger to reach maximum speed) may in some cases include any degree of decrease or increase. In some cases, the increase, decrease, or increase may be compared to the relevant parameters when using the fuel composition prior to incorporating the viscosity index (VI) improving additive. It is intended for use in internal combustion (typically diesel) engines (eg, commercially available) before adding a viscosity index (VI) enhancing additive to the fuel composition. It may be compared to the relevant parameters measured when the same engine is run on the composition.

The present invention is used, for example, to meet a desired goal of the properties and / or performance and / or effect of a fuel composition, in particular on the acceleration and / or output performance of an internal combustion engine, by means of a viscosity index (VI) improver. May include adjusting.

The improvement in acceleration performance may also include at least some mitigation in the deterioration of acceleration performance due to another cause, in particular another fuel component or additive contained in the fuel composition. As an example, a fuel composition can contain one or more components intended to reduce the overall density in order to reduce the level of emissions produced during combustion, and the reduction in density is Although it can result in loss of engine power, this effect can be overcome or at least mitigated by the use of the Viscosity Index (VI) improver according to the invention.

Improved acceleration performance is due to other reasons, such as the use of fuels containing oxygenated components (eg, so-called "biofuels") or the accumulation of combustion-related deposits in the engine (typically in the fuel injector). It may also include at least a partial recovery of reduced acceleration performance.

When using the present invention to increase engine torque at a given engine speed, typically during an acceleration period, the increase will drive the engine with the fuel composition prior to incorporating the Viscosity Index (VI) improver. At least 0.1%, preferably at least 0.2% or 0.3% or 0.4% or 0.5%, and in some cases at least 0.6% or 0, as compared to what would be obtained if It can be 0.7%. This increase is intended for use in internal combustion (typically diesel) engines (eg, commercially available) before adding a viscosity index (VI) improver to the fuel composition. Can be compared to the engine torque obtained at the appropriate speed when the same engine is run on.

When using the present invention to increase engine power at a given engine speed, typically during an acceleration period, the increase again ran the engine with the fuel composition prior to incorporating the viscosity index improver. At least 0.1%, preferably at least 0.2% or 0.3% or 0.4% or 0.5%, and in some cases at least 0.6% or 0. It can be 7%. This increase is the same engine in other similar fuel compositions (eg, commercially available) intended for use in internal combustion (typically diesel) engines before adding a viscosity index improver to the fuel composition. Can be compared to the engine output obtained at the appropriate speed when activated.

When using the present invention to increase the engine VTE at a given engine speed, typically during an acceleration period, the increase is again the engine in the fuel composition before incorporating the viscosity index (VI) improver. At least 0.1%, preferably at least 0.2% or 0.3% or 0.4% or 0.5%, and in some cases at least 0.6%, as compared to what would be obtained if Or it can be 0.7%. This increase is the same engine with other similar fuel compositions (eg, commercially available) intended for use in internal combustion (typically diesel) engines before adding a viscosity index (VI) improver. When activated, it can be compared to the VTE obtained at the appropriate speed.

When using the present invention to reduce the time it takes for an engine to accelerate between two given engine speeds, the reduction is to run the engine with a fuel composition prior to incorporating a viscosity index (VI) improver. At least 0.1%, preferably at least 0.2% or 0.3% or 0.4% or 0.5%, and in some cases at least 0.6% or 0.7, as compared to the case. %, Or 0.8% or 0.9%. This shortening is intended for use in internal combustion (typically diesel) engines (eg, commercially available) before adding a viscosity index (VI) improver to the fuel composition. Can be compared to the acceleration time between applicable speeds when running the same engine at. The acceleration time is, for example, 300 rpm or more, or 400 rpm or more, 500 rpm or more, 600 rpm or more, 700 rpm or more, 800 rpm or more, 900 rpm or more, or 1000 rpm or more, for example, 1300 to 1600 rpm, or 1600 to 2200 rpm, or 2200 to 3000 rpm, or 3000 to 3000. It can be measured over an increase in engine speed of 4000 rpm.

According to the present invention, the automobile fuel composition in which the VI improving additive is used can be a diesel fuel composition particularly suitable for use in a diesel engine. It may be used in any type of compression ignition engine, such as those described below, and / or may be suitable, and / or adapted and / or intended to be used.

Viscosity index-enhancing additives (also called VI-improving agents) are already well known for use in lubricant formulations and increase the viscosity at high temperatures to keep the viscosity as constant as possible over the desired temperature range. Used to maintain. They are typically based on relatively high molecular weight long chain polymer molecules capable of forming agglomerates and / or micelles. Since these molecular systems expand at high temperatures, their movements are further restricted and the viscosity of the system increases.

The VI improving additive used in the fuel composition according to the present invention includes a polyisoprene-based star polymer, particularly a styrene-isoprene star polymer.

Examples of suitable styrene-isoprene star polymers include those disclosed in US2013 / 0165362, which are incorporated herein by reference in their entirety. The star polymer disclosed in US2013 / 0165362 has multiple triblock arms attached to a central core such as a divinylbenzene (DVB) core, which triblock arms are two moieties derived from a diene. It contains a block derived from a monoalkenyl array monomer located between targeted or fully hydrided blocks, at least one of which is a copolymer derived from a mixed diene monomer and is an incorporated monomer. About 65% to about 95% by weight of the units are from isoprene and from about 5% to about 35% by weight of the incorporated monomeric units are from butadiene, at least about 80% by weight, preferably at least about 90%. By weight% butadiene is incorporated into the random copolymer block in a 1,4-configuration.

A preferred viscosity index (VI) enhancing additive for use in fuel compositions is the star-shaped isoprene polymer described in US2013 / 0165362, which can be characterized by the following formula.
(D'-PA-D'') n-X;
In the formula, D'represents a diene-derived "outer" block, PA represents a monoalkenylarene-derived block, D'' represents a diene-derived inner random, and n represents an arm 1 mol. The average number of arms per star-shaped polymer formed by the reaction of 2 mol or more of the polyalkenyl coupling agent per unit is represented, and X represents the core of the polyalkenyl coupling agent.

At least one of the diene blocks D'and D'', preferably each of the diene blocks D'and D', is a copolymer block derived from a mixed diene monomer, from about 65% by weight to about 65% by weight of the incorporated monomer unit. 95% by weight is from isoprene and from about 5% to about 35% by weight of the monomer units incorporated is from butadiene, with at least about 80% by weight of butadiene, preferably at least 90% by weight of butadiene. Incorporated in 4-arrangement. Preferably, at least about 15% by weight of the incorporated monomer units are butadiene monomer units. Preferably, about 28% by weight or less of the incorporated monomer unit is a butadiene monomer unit. Preferably, at least one of the diene blocks D ″ and D ″, more preferably each of the diene blocks D ″ and D ″ ″ is a random copolymer block. The blocks D ″ and D ″ are preferably hydrogenated to remove at least about 80% or 90% or 95% of the unsaturated, more preferably completely hydrogenated.

The outer block D'has a number average molecular weight of about 10,000 to about 120,000 Daltons, more preferably about 20,000 to about 60,000 Daltons prior to hydrogenation. Block PA has a number average molecular weight of about 10,000 to about 50,000 Daltons. Increasing the size of the block PA can adversely affect the thickening efficiency of the star polymer. Therefore, the number average molecular weight of block PA is preferably from about 12,000 to about 35,000 daltons. The inner block D'has a number average molecular weight of about 5,000 to about 60,000 daltons, more preferably about 10,000 to about 30,000 daltons, prior to hydrogenation. As used herein, the term "number average molecular weight" refers to a number average molecular weight measured by gel permeation chromatography ("GPC") using polystyrene standards.

In the star polymers used herein, the ratio of the number average molecular weight of the outer block D'to the number average molecular weight of the inner block D'''is preferably at least about 1.4: 1, for example at least about 1. It is 9.9: 1, more preferably at least about 2.0: 1, and the ratio of the number average molecular weight of the block PA to the number average molecular weight of the inner block D'''is preferably at least about 0.75 :. 1, for example at least about 0.9: 1, more preferably at least about 1.0: 1.

Preferably, 30% by weight or less, more preferably 25% by weight or less, of the total amount of polydiene in the star polymer is derived from butadiene. Preferably, at least about 80% by weight, more preferably at least about 90% by weight, of the total amount of butadiene that can be incorporated into the polymer as a 1,2- or 1,4-configuration unit is incorporated in the 1,4-configuration. Incorporated into the mold polymer. Increasing the proportion of butadiene incorporated into the polymer by 1,4-units can increase the thickening efficiency properties of the star polymer. Excessive amounts of polybutadiene, especially those with a 1,2-configuration, can adversely affect pump pumping characteristics at low temperatures.

The isoprene monomer used as a precursor of the copolymers herein can be incorporated into the polymer as either a 1,4- or 3,4-configuration, or a mixture thereof. Preferably, the majority of isoprene exceeds about 60% by weight, more preferably more than about 80% by weight (such as about 80% to 100% by weight), more preferably more than about 90% by weight (about 93% by weight). % ~ 100% by weight, etc.) Incorporated into the polymer as 1,4-units.

Suitable monoalkenyl arene monomers include monovinyl aromatic compounds such as styrene and monovinylnaphthalene, and alkylated derivatives thereof (such as o-, m- and p-methylstyrene, α-methylstyrene and tertiary butylstyrene). Can be mentioned. The preferred monoalkenyl arene is styrene.

The star polymer used herein may have 4 to about 25 arms (n = about 4 to about 25), preferably about 10 to about 20 arms. The star polymers used herein are from about 100,000 to about 1,000,000 daltons, preferably from about 400,000 to about 800,000 daltons, more preferably from about 500,000 to about 700,000. It may have a total number average molecular weight of Dalton.

Further details of the structures, properties, and methods for making these preferred star polymers, including various polymerization preparation methods, are disclosed in US2013 / 0165362, which is incorporated herein by reference in its entirety. Is done.

Another suitable type of viscosity index (VI) enhancing additive for use herein is a star-shaped polyisoprene polymer containing a crosslinked polystyrene core with hydrogenated polyisoprene or poly (alternate ethylene-propylene) arms. Is. An example of such a polymer is SV300, which is commercially available from Infinium. As disclosed in US2017 / 025370, the SV300 contains a 6 wt% crosslinked polystyrene star-shaped core with 30 arms of hydrogenated polyisoprene or poly (alternate ethylene-propylene) and has an overall molecular weight. Is 875,000 and the hydrodynamic radius in PAO4 (a polyalphaolefin commercially available from ExxonMobil ^{with a viscosity of about 4 mm 2} / sec at 100 ° C.) is 25 nm.

The density of the viscosity index (VI) improving additive (ASTM D-4052) for use herein at 15.6 ° C. is 0.70 g / cm ³ or higher, preferably 0.75 g / cm ³ or higher. ..

Examples of commercially available viscosity index (VI) improving additives suitable for use herein include those commercially available from Infinium under trade names such as SV300, SV600, SV260.

A particularly preferable viscosity index (VI) improving additive from the viewpoint of improving the lubrication characteristics and the output characteristics of the fuel composition is SV600 commercially available from Infinium.

The VI-enhancing additive is a suitable solvent, such as mineral oil or an oil such as a Fisher-Tropsch-derived hydrocarbon mixture; a light oil if the additive is intended for use in a fuel composition (eg, a diesel fuel composition). Fuel components compatible with (or intermediate distillate fuel components such as kerosene) (again, either from minerals or Fisher Tropsch); polyalphaolefins; fatty acid alkyl esters (FAAEs), Fisher Tropsch Derived biomass-so-called biofuels such as liquid synthetic products, hydrided vegetable oils, waste or alcohols such as algae oil or ethanol; aromatic solvents; any other hydrocarbon or organic solvent; or in mixtures thereof. Can be pre-dissolved. Preferred solvents for use in this context are mineral oil-based diesel fuel components and solvents, as well as Fischer-Tropsch-derived components such as the "XtL" component referred to below. In some cases, biofuel solvents are also preferred.

The concentration of the VI improving additive in the fuel composition is up to 1% w / w (10,000 ppm), preferably up to 0.5% w / w, and in some cases up to 0.4 or 0.3 or 0. It can be .25% w / w. The concentration is 0.001% w / w or more, preferably 0.01% w / w or more, preferably 0.02 or 0.03 or 0.04 or 0.05% w / w or more, and in some cases, It may be 0.1 or 0.2% w / w or more. Suitable concentrations are, for example, 0.001 to 1% w / w, or 0.001 to 0.5% w / w, or 0.05 to 0.5% w / w, or 0.05 to 0. It may be 25% w / w, for example 0.05 to 0.25% w / w, or 0.1 to 0.2% w / w.

The rest of the composition typically consists of one or more automotive-based fuels, optionally with one or more fuel additives, as described in more detail below.

The above concentrations are for the VI improving additive itself and do not take into account the solvent in which the active ingredient is pre-diluted. They are based on the mass of the total fuel composition. Two or more VI-improving additives can be used in the fuel compositions herein. When a combination of two or more VI-enhancing additives is used in the composition, the same concentration range may be applied to the overall combination, excluding any precursor solvent that is also present here.

The concentration of the VI-enhancing additive depends on the desired viscosity of the total fuel composition, the viscosity of the composition before incorporating the additive, the viscosity of the additive itself, and the viscosity of any solvent in which the additive is used. The relative proportions of VI-enhancing additives, fuel components and any other components or additives present in the automotive fuel composition prepared in accordance with the present invention are other factors such as density, emission performance and cetane number, especially density. Can also depend on the desired properties of.

Surprisingly, it has been found that the VI-enhancing additives described herein can not only increase the lubricity of the fuel composition, but also increase the power and / or acceleration properties.

Due to the inclusion of VI improving additives, fuel compositions prepared according to the present invention (particularly diesel fuel compositions) are preferably 2.7 or 2.8 mm ² / sec or more, preferably 2.9 or 3 .0 or 3.1 or 3.2 or 3.3 or 3.4 mm ² / sec or more, in some cases 3.5 or 3.6 or 3.7 or 3.8 or 3.9, or even 4 mm ^It has a VK40 of 2 / sec or more. The VK40 can be up to 4.5 or 4.4 or 4.3 mm ² / sec. In some cases, for example, in the case of a frigid diesel fuel, the VK40 of the composition may ^{be as low as 1.5 mm 2} / sec, but preferably 1.7 or 2.0 mm ² / sec or more. References to viscosity herein are intended to mean kinematic viscosity unless otherwise stated.

The composition preferably has a relatively high density, for example, in the case of a diesel fuel composition, 830 kg / m ³ or more (ASTM D-4052 or EN ISO3675) ^{at 15 ° C., preferably 832 kg / m 3} or more, for example. It is 823 to 860 kg / m ³ . Preferably, its density is 845 kg / m ³ or less at 15 ° C., which is the upper limit of the current EN590 diesel fuel specifications.

The fuel composition prepared according to the present invention may be, for example, an automotive gasoline or diesel fuel composition, particularly the latter.

The gasoline fuel composition prepared according to the present invention can generally be any kind of gasoline fuel composition suitable for use in a spark ignition (gasoline) engine. In addition to the VI-enhancing additive, it may contain other standard gasoline fuel components. For example, typically, most can be occupied by gasoline-based fuels having a boiling point range of 20 ° C to 210 ° C (ASTM D-86 or EN ISO3405). By "most" in this context is typically 85% w / w or more, more preferably 90 or 95% w / w or more, most preferably 98 or 99 or 99, based on the total fuel composition. It means 5.5% w / w or more.

The diesel fuel composition prepared according to the present invention can generally be any kind of diesel fuel composition suitable for use in a compression ignition (diesel) engine. It may contain other standard diesel fuel components in addition to the VI improving additive. For example, most can be occupied by the types of diesel-based fuels listed below. Again, "most" is typically 85% w / w or more, more preferably 90 or 95% w / w or more, most preferably 98 or 99 or 99. It means 5% w / w or more.

Therefore, in addition to the VI-enhancing additive, the diesel fuel composition prepared according to the present invention may contain one or more conventional diesel fuel components. Such components typically include liquid hydrocarbon intermediate distillate fuel oils, such as petroleum-derived gas oil. In general, such fuel components can be derived organically or synthetically and are suitably obtained by distilling a desired range of fractions from crude oil. They typically have a boiling point within the normal diesel range of 150-410 ° C or 170-370 ° C, depending on grade and application. Typically, the fuel composition comprises one or more decomposition products obtained by decomposing heavy hydrocarbons.

Light oil derived from petroleum can be obtained, for example, by refining a crude oil source and optionally (hydrogenating) it. It can be a single gas oil stream obtained from such a refining process, or a mixture of several gas oil fractions obtained in a refining process via different processing routes. Examples of such gas oil distillates are gas oil, gas oil under reduced pressure, gas oil obtained in a pyrolysis process, light and heavy cycle oils obtained in a fluid cracking unit, and gas oil obtained from a hydrocracking unit. Optionally, the petroleum-derived gas oil may contain some petroleum-derived kerosene fractions.

Such gas oil can be treated with a hydrodesulfurization (HDS) unit to reduce their sulfur content to levels suitable for inclusion in diesel fuel compositions.

The diesel-based fuel may be or may contain a Fischer-Tropsch-derived diesel fuel component, typically Fischer-Tropsch-derived gas oil. In the context of the present invention, the term "derived from Fischer-Tropsch" means that the material is or is derived from a synthetic product of the Fischer-Tropsch condensation process. The term "from non-Fischer-Tropsch" can be interpreted accordingly. Thus, the Fischer-Tropsch-derived fuel or fuel component is a hydrocarbon stream obtained in large part directly or indirectly from the Fischer-Tropsch condensation process, with the exception of the added hydrogen.

The Fischer-Tropsch reaction converts carbon monoxide and hydrogen into long-chain, usually paraffinic hydrocarbons.
n (CO + 2H ₂ ) = (-CH _2- ) n + nH ₂ O + heat,
Typically at high temperatures (eg, 125-300 ° C, preferably 175-250 ° C) and / or pressure (eg, 0.5-10 MPa, preferably 1.2-5 MPa) in the presence of a suitable catalyst. source. If desired, hydrogen: carbon monoxide ratios other than 2: 1 can be used.

Carbon monoxide and hydrogen can themselves be derived from organic, inorganic, natural or synthetic sources, typically natural gas or organically derived methane.

The Fischer-Tropsch-derived diesel fuel component used in the present invention is obtained directly from the purification or Fischer-Tropsch reaction, or indirectly, for example, by fractionation or hydrogenation of the refined or synthetic product, fractionation or A hydrotreated product can be obtained. The hydrotreating is cold flow by hydrocracking to adjust the boiling range (see, eg, GB-B-2077289 and EP-A-0148773) and / or increasing the proportion of branched paraffins. Accompanied by hydrogenation isomerization that can improve properties. EP-A-0583836 first subject the Fisher-Tropsch synthetic product to hydroconversion under conditions that are substantially free of isomerization or hydrocracking (so that the olefin and oxygen-containing components are hydrogenated). ), Then, at least a portion of the resulting product is hydrogenated and converted under conditions such that hydrocracking and isomerization can result in a substantially paraffin-based hydrocarbon fuel. The hydrogenation treatment method is described. The desired fraction, typically the gas oil fraction, can then be isolated, for example by distillation.

Other post-synthesis treatments such as polymerization, alkylation, distillation, decomposition-decarboxylation, isomerization and hydrogenation modification are described, for example, in US-A-415566 and US-A-4478955. As such, it can be used to modify the properties of the Fischer-Tropsch condensation product.

Typical catalysts in Fisher-Tropsch synthesis of paraffinic hydrocarbons include metals from Group VIII of the Periodic Table, in particular ruthenium, iron, cobalt, or nickel, as catalytically active ingredients. Such suitable catalysts are described, for example, in EP-A-0583836.

An example of a Fischer-Tropsch-based process is Shell ™ "Gas-to-Liquids" or "GtL" technology (formerly known as SMDS (Shell Middle Distillate Synthesis), " The Shell Middle Distillate Synthesis Process ”, van der Burgt et al., 5th Synthetic World Synthetic, Washington DC, The same article published in November 1985, TanLonLonLon, and Sell. (Described in the November publication). In the latter case, the preferred characteristics of the hydroconversion process may be as disclosed herein. This process is heavy on natural gas. By converting to chain hydrocarbon (paraffin) wax, a product in the intermediate distillate range can be produced, which can then be hydroconverted and distilled.

For use in the present invention, the Fischer-Tropsch-induced fuel component is preferably derived from any suitable component derived from gas-to-liquid synthesis (GtL component), or similar Fischer-Tropsch synthesis. A component that converts gas, biomass, or coal into a liquid (hereinafter referred to as an XtL component). The component derived from Fischer-Tropsch is preferably a GtL component. It can be a BtL (biomass to liquid) component. In general, a suitable XtL component may be, for example, an intermediate distillate fuel component selected from kerosene, diesel oil and gas oil fractions known in the art, such components as synthetic process fuels or synthetic process oils. Can be generally classified. Preferably, the XtL component for use as a diesel fuel component is light oil.

Diesel fuel components contained in compositions prepared according to the present invention typically have ^{a density of 750-900 kg / m 3} at 15 ° C., preferably 800-860 kg / m ³ (ASTM D-4052 or EN). It has ISO3675) and / or 1.5-6.0 mm ² / sec VK40 (ASTM D-445 or EN ISO3104).

In the diesel fuel composition prepared according to the present invention, the base fuel itself may contain a mixture of two or more diesel fuel components of the above types. It may be a so-called "biodiesel" fuel component, such as a vegetable oil, a hydride vegetable oil or a vegetable oil derivative (eg, a fatty acid ester, especially a fatty acid methyl ester), or another oxidant, such as an acid, ketone or ester, or They may be contained. Such components do not necessarily have to be bio-derived.

Automotive diesel fuel compositions prepared in accordance with the present invention preferably comply with applicable current standard specifications (s) such as EN590 (for Europe) or ASTM D-975 (for the United States). .. As an example, the total fuel composition has ^{a density of 820-845 kg / m 3} at 15 ° C (ASTM D-4052 or EN ISO3675); a T95 boiling point below 360 ° C (ASTM D-86 or EN ISO3405); measurements of 51 or greater. Cetane number (ASTM D-613); ^{2 to} 4.5 mm 2 / sec VK40 (ASTM D-445 or EN ISO3104); sulfur content of 50 mg / kg or less (ASTMD-2622 or EN ISO20846); and / or 11 It may have a polycyclic aromatic hydrocarbon (PAH) content (IP391 (mod)) of less than% w / w. However, relevant specifications vary from country to country and from year to year and may depend on the intended use of the fuel composition.

Diesel fuel compositions prepared according to the present invention preferably contain less than 5000 ppmw (per million by weight), typically 2000-5000 ppmw, or 1000-2000 ppmw, or up to 1000 ppmw of sulfur. The composition may contain, for example, a low sulfur or ultra-low sulfur fuel, or a sulfur-free fuel, such as up to 500 ppmw, preferably 350 ppmw or less, most preferably 100 or 50 ppmw or less, and even 10 ppmw sulfur.

The automotive fuel composition prepared in accordance with the present invention, or the base fuel used in such compositions, may or may not be added (with additives). It may be added, for example, in refineries, for example, antistatic agents, pipeline drag receptors, fluidity improvers (eg, ethylene / vinyl acetate copolymers or acrylates / maleic anhydride copolymers). It contains a small amount of one or more additives selected from lubricating additives (other than the above-mentioned VI improving additives), antioxidants, and wax sedimentation inhibitors. Therefore, the composition, in addition to the VI-improving additive, has a small proportion (preferably 1% w / w or less, more preferably 0.5% w / w (5000 ppmw) or less, most preferably 0.2% w / w / or less. W (2000 ppmw) or less) may contain one or more fuel additives.

The composition may contain, for example, a cleaning agent. Detergent-containing diesel fuel additives are known and commercially available. Such additives may be added to diesel fuel at levels intended to reduce, remove, or delay the accumulation of engine deposits.

Examples of cleaning agents suitable for use in fuel additives for the purposes of the present invention are polyolefin-substituted succinimides or polyamine succinimides such as polyisobutylene succinimide or polyisobutyleneamine succinamides, aliphatic amines, Mannig bases or amines. And polyolefins (eg, polyisobutylene) maleic anhydride. Succinimide dispersant additives are, for example, GB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-06139938, EP-A-0557516, and WO-A-98. / 42808. Particularly preferred are polyolefin-substituted succinimides such as polyisobutylene succinimide.

The fuel additive mixture that can be used in the fuel composition prepared according to the present invention may contain other components in addition to the cleaning agent. Examples include lubricity improvers; anti-fog agents such as alkoxylated phenolformaldehyde polymers; antifoaming agents (eg polyether-modified polysiloxane); ignitability improvers (cetan value improvers) (eg 2-ethylhexyl nitrate (EHN) ), Cyclohexyl nitrate, di-tert-butyl peroxide and those disclosed in US-A-4208190, column 2, lines 27 to 3, line 21); rust inhibitors (eg, propane of tetrapropenyl succinic acid). A -1,2-diol semi-ester, or a polyhydric alcohol ester of a succinic acid derivative, wherein the succinic acid derivative is unsubstituted and contains 20 to 500 carbon atoms in at least one of its α-carbon atoms. Alternatively, it has a substituted aliphatic hydrocarbon group, for example, a pentaerythritol diester of a polyisobutylene substituted succinic acid); a corrosion inhibitor; a fragrance agent; an abrasion resistant additive; an antioxidant (for example, 2,6-di-). Phenolic compounds such as tert-butylphenol or phenylenediamines such as N, N'-di-sec-butyl-p-phenylenediamine); metal deactivators; combustion improvers; static eliminators; low temperature flow improvers; And wax settling inhibitors.

Such fuel additive mixtures may contain lubricity improvers (in addition to the viscosity-enhancing (VI) additives described above), especially if the fuel composition has a low sulfur content (eg, 500 ppmw or less). In the added fuel composition, the lubricity improver is preferably present at a concentration of less than 1000 ppmw, preferably 50 to 1000 ppmw, more preferably 70 to 1000 ppmw. Suitable commercially available lubricity improvers include ester-based and acid-based additives. Other lubricity improvers are associated with patent literature, especially their use in low sulfur content diesel fuels, eg:
-Damping Wei and H. A. Papers, "The Lubricity of Diesel Fuels", Wear, III (1986), pp. 217-235,
-WO-A-95 / 33805-Low temperature fluidity improver to improve lubricity of low sulfur fuel,
-WO-A-94 / 17160-Specific esters of carboxylic acids and alcohols as fuel additives for wear reduction in diesel engine injection systems, where the acid has 2 to 50 carbon atoms. Alcohols have one or more carbon atoms), especially glycerol monooleates and diisodecyl adipates,
-US-A-5490864-Specific dithiophosphate diesters as wear-resistant lubricating additives for low-sulfur diesel fuel-dialcohol, and-WO-A-98 / 01516-bonded to aromatic nuclei. It is described in a specific alkyl aromatic compound having at least one carboxyl group, which imparts a wear resistant lubrication effect, especially in a low sulfur diesel fuel.

The advantage of the present invention is that the amount of other lubricating additives can be reduced or even reduced, as the lubricity of the fuel composition can be improved by including the viscosity-enhancing (VI) additives disclosed above. It can be excluded.

Further, the fuel composition preferably contains a defoaming agent, and more preferably contains a rust inhibitor and / or a corrosion inhibitor and / or a lubricity improving additive in combination.

Unless otherwise stated, the (active substance) concentration of each additive in the fuel composition to be added is preferably in the range of up to 10,000 ppmw, more preferably 0.1 to 1000 ppmw, preferably 0.1 to 300 ppmw, eg 0. .1-150 ppmw.

The (active substance) concentration of any anti-fog agent in the fuel composition is preferably 0.1 to 20 ppmw, more preferably 1 to 15 ppmw, even more preferably 1 to 10 ppmw, and preferably 1 to 1. It is within the range of 5 ppmw. The (active substance) concentration of any ignitability improver present is preferably 2600 ppmw or less, more preferably 2000 ppmw or less, and preferably 300-1500 ppmw or less. The (active substance) concentration of any cleaning agent in the fuel composition is preferably in the range of 5 to 1500 ppmw, more preferably 10 to 750 ppmw, and most preferably 20 to 500 ppmw.

If desired, one or more additive components (eg, those listed above) may be comixed in the additive concentrate (preferably with a suitable diluent) and then This additive concentrate can be dispersed in the base fuel or fuel composition. VI-enhancing additives can be incorporated into such additive formulations according to the present invention.

In the case of diesel fuel compositions, for example, the fuel additive mixture is typically a solvent such as that sold under the "SHELLSOL" trademark by the mineral oil, Shell companies, along with other components as described above. esters, especially an alcohol (e.g. hexanol, 2-ethylhexanol, decanol, isotridecanol) polar solvents, and Shell alcohol mixtures such as those sold under the registered trademark "LINEVOL" by companies such as, in particular _{C. 7 to It} contains a cleaning agent along with a LINEVOL 79 alcohol, which is a mixture of 9 primary alcohols, or a diesel fuel compatible diluent, which is a _{commercially available alcohol mixture of C 12-14.}

The total content of the additives in the fuel composition is preferably 0 to 10000 ppmw, preferably less than 5000 ppmw.

In the present specification, the amount of the component (concentration,% v / v, ppmw,% w / w) is the amount of the active substance, excluding the volatile solvent / diluent.

Additives of different types and / or concentrations may be suitable for use in gasoline fuel compositions and may contain, for example, polyisobutylene / amine and / or polyisobutylene / amide copolymers as cleaning additives.

Preferably, the VI improving additive, and the concentration at which it is used in the fuel composition, is at a low temperature filter clogging point (CFPP) of 10 ° C. or lower, preferably 5 ° C. or 2 ° C. or 1 ° C. or lower. It will be something that causes an increase. Preferably, it will not cause an increase in CFPP. It may cause a decrease in CFPP. The increase in CFPP can be compared to the CFPP in the fuel composition prior to incorporating the VI-improving additive. They are compared to CFPP of other similar fuel compositions intended for use in internal combustion (especially diesel) engines (eg, commercially available) prior to the addition of VI-enhancing additives to the fuel composition. possible. CFPP can be measured using standard test method EN116.

Preferably, the VI improving additive, and the concentration at which it is used in the fuel composition, is such that it causes an increase in cloud point of the composition below 10 ° C, preferably below 5 ° C or 2 ° C or 1 ° C. Will be. Those that do not cause an increase in cloud point are preferable. It may cause a decrease in cloud point. The increase in cloud point can be a comparison with the cloud point of the fuel composition before incorporating the VI improving additive. They are compared to the cloud point of other similar fuel compositions intended for use in internal combustion (especially diesel) engines (eg, commercially available) before adding the VI-enhancing additive to the fuel composition. Can be done. Cloud points can be measured using standard test method EN23015.

In the context of the present invention, the "use" of a VI-enhancing additive in a fuel composition refers to the VI-improving additive, typically one or more fuel components (typically diesel-based fuels) and optionally one. Means incorporating into a composition as a mixture (ie, a physical mixture) with one or more fuel additives. The VI-enhancing additive is conveniently incorporated before the composition is introduced into the engine driven by the composition. Alternatively or in addition, the use may include running the engine with a fuel composition containing a VI improving additive, typically by introducing the composition into the combustion chamber of the engine.

The "use" of a VI-enhancing additive according to the invention is also an internal combustion engine (typically, one in which the composition is introduced or is intended to be introduced, in order to achieve one or more of the above-mentioned objectives. Diesel) In order to improve the acceleration performance of an engine, it may include supplying such additives with instructions for its use in an automotive fuel composition.

The VI-enhancing additive is itself suitable for use as a fuel additive, particularly a diesel fuel additive, and / or may be supplied as a component of the intended formulation, in which case the VI-improving additive. The agent affects the lubricity of the automotive fuel composition and / or its effect on the acceleration performance and / or power of the engine into which or is intended to be introduced. It may be included in such formulations for the purpose of feeding.

Thus, the VI-enhancing additive can be incorporated into an additive formulation or package with one or more other fuel additives. It may be, for example, one or more selected from a detergent, an anti-corrosion additive, an ester, a polyalphaolefin, a long chain organic acid, an amine or a component containing an amide active center, and a mixture thereof in an additive formulation. May be combined with the fuel additive of. In particular, it may be combined with one or more so-called performance additives, typically including at least a cleaning agent.

The VI-enhancing additive can be added directly into the fuel component or composition, for example in a refinery. It can then be pre-diluted with suitable fuel components that form part of the entire automotive fuel composition.

According to the present invention, two or more VI improving additives can be used in automotive fuel compositions for the above purposes.

According to a further aspect of the invention, a process for preparing an automotive fuel composition is provided, the process comprising mixing the automotive base fuel with a VI improving additive, the VI improving additive being star-shaped. It is an isoprene polymer. Mixing is one of the above objectives with respect to the lubricity of the resulting fuel composition and / or the effect on the acceleration performance and / or power of the internal combustion engine into which it is introduced or intended to be introduced. Can be carried out for one or more of. The composition can be, in particular, a diesel fuel composition.

The VI-enhancing additive can be mixed with other components of the composition, especially the base fuel, for example in refineries. Alternatively, it may be added to the automotive fuel composition downstream of the refinery. It can also be added as part of an additive package containing one or more other fuel additives.

A further aspect of the invention provides a method of operating an internal combustion engine and / or a vehicle powered by such an engine, the method comprising introducing the above fuel composition into the combustion chamber of an engine. .. Again, the fuel composition is preferably introduced for one or more of the purposes described in connection with the present invention. Therefore, it is preferred that the engine be operated with a fuel composition for the purpose of improving its lubricity and / or acceleration performance and / or power.

Again, the engine can be a diesel engine in particular. It may be a turbocharged engine, especially a turbocharged diesel engine. The diesel engine may be a direct injection type, for example, a rotary pump, an in-line pump, a unit pump, an electronic unit injector or a common rail type, or an indirect injection type. It may be a heavy load or light load diesel engine. It can be an electronic unit direct injection (EUDI) engine in particular.

Throughout the description and claims herein, the terms "comprise" and "contain" and variations of these terms, such as "comprising" and "comprises". Means "includes, but is not limited to," and does not exclude other parts, additives, ingredients, integers or steps.

Throughout the description and claims herein, the singular includes the plural, unless the context requires otherwise. In particular, when indefinite articles are used, the specification should be understood as intended not only in the singular but also in the plural, unless the context requires otherwise.

Preferred features of each aspect of the invention may be as described in relation to any of the other aspects.

Other features of the invention will become apparent from the following examples. Generally speaking, the invention extends to any novel or any novel combination of features disclosed herein, including any of the appended claims and drawings. Accordingly, features, integers, properties, compounds, chemical moieties or groups described in connection with a particular aspect, embodiment or embodiment of the invention may be any other described herein as long as they are not inconsistent. It should be understood that it is applicable to the embodiment, embodiment or embodiment of.

Further, unless otherwise specified, any feature disclosed herein may be replaced by an alternative feature that serves the same or similar purpose.

The following examples show the properties of automotive fuel compositions prepared according to the present invention and evaluate the effect of such compositions on the performance of diesel engines.

A fuel mixture was prepared by combining a diesel-based fuel (according to the European diesel fuel standard EN590) and a viscosity index (VI) improving additive. The Viscosity Index (VI) additives used in this experiment were SV150, SV260, SV300 and SV600 at either 500 mg / kg or 1000 mg / kg treatment rates.

SV150 is a linear diblock polymer commercially available from Infinium and is used as a comparison in this example.

SV260 is a star-shaped styrene-polyisoprene polymer commercially available from Infinium.

SV300 is a star-shaped styrene-polyisoprene polymer commercially available from Infinium.

SV600 is a star-shaped styrene-polyisoprene polymer commercially available from Infinium.

Prior to addition to the diesel-based fuel, the VI-improving additive was premixed with Shellsol A150 solvent (commercially available from Shell). The weight ratio of VI-improving additive to Shellsol A150 was 1: 8.

The fuel specifications of the diesel-based fuel used in this embodiment are shown in Table 1 below.

Demonstration of Output Gain The above fuel mixture containing the VI additive premixed with Shellsol A150 was used in a bench test engine to evaluate the effect of the VI improving additive on the output performance of the engine. The bench test engine selected for this study was PSADW10B. Since this engine is specified in CEC F-98-09 (industry standard test for injector nozzle fouling in the latest DI automobile engines), a huge amount of historical test data is available to support the performance and characteristics of the engine. Is. Details of the DW10B test are listed in Table 2 below.

The maximum accelerator pedal position (100% APP) was applied using the DW10B CEC specification nozzle at a constant test speed of 4000 rpm. The engine was run in a cycle of 24 minutes per fuel, alternating between additive-free base fuel and candidate fuel, and power was measured. The results of the output test are shown in Table 3 below. The output gain (%) is compared to the additive-free base fuel (containing Shellsol A150) (designated as Example 1 in Table 3).
Demonstration of lubricity

The fuel mixture has also undergone an HFRR test (according to ISO 12156) to measure lubricity. HFRR (High Friction Reciprocating Rig) is a controlled reciprocating friction and wear tester used to evaluate the lubrication performance of fuels and lubricants. In this test, fuel was soaked and a load was applied to the flat surface of a fixed steel disc with a steel ball having a diameter of 6 mm to reciprocate. At the end of each test, balls and discs were removed from the test rig, rinsed with toluene and isopropanol, and then treated with a solution of 0.05 wt% ethylenediaminetetraacetic acid (EDTA) for 60 seconds. Then, using SWLI Veco Wyko model NT9100, topographic images were acquired and analyzed in order to determine the amount of wear of the wear marks on the balls and discs. The device was set to vertical scanning interferometry (VSI) mode and calibrated to measure rough surfaces in the nanometer detection range. The results of the HFRR test are shown in Table 4 below. The rate of change (%) in diameter of the wear marks is compared with the additive-free base fuel (containing Shellsol A150) (designated as Example 8 in Table 4). A result with a negative rate of change indicates profit.

Discussion The fuel mixture containing the star-shaped styrene-polyisoprene polymer SV300 has an output gain (1000 mg / kg and) compared to the fuel mixture containing the linear diblock polymer SV150 (see Examples 2 and 3). It showed a significant increase (at both 500 mg / kg) (see Examples 4 and 5).

A fuel mixture containing the star-shaped styrene-polyisoprene polymer SV600 at 1000 mg / kg showed an increase in output gain compared to the base fuel (see Examples 6 and 7). The fuel mixture containing the star-shaped styrene-polyisoprene polymer SV600 at 1000 mg / kg did not show as much output gain as the fuel blend containing the linear diblock polymer SV150, but showed significantly better lubrication performance. (See Examples 6 and 13).

The fuel mixture containing 1000 mg / kg of the star-shaped styrene-polyisoprene polymer SV260 (Example 15) showed improved lubrication performance as compared to the fuel mixture containing 1000 mg / kg of SV150 (Example 9). ..

The fuel mixture containing 1000 mg / kg of the star-shaped styrene-polyisoprene polymer SV260 (Example 15) showed improved lubrication performance as compared to the fuel mixture containing 1000 mg / kg of SV150 (Example 9). ..
The present specification includes the following aspects of the invention.
[1]
A fuel composition comprising a base fuel and at least one viscosity index (VI) improving additive, wherein the viscosity index (VI) improving additive is a star-shaped polyisoprene-based polymer.
[2]
The star-shaped polyisoprene-based polymer is characterized by the following formula.
(D'-PA-D'') n-X;
In the formula, D'represents a block derived from at least one diene, PA represents a block derived from monoalkenylarene, D'' represents a block derived from a diene, and n represents a mole of arm. Represents the average number of arms per star-shaped polymer formed by the reaction of 2 mol or more of the polyalkenyl coupling agent, where X represents the nucleus of the polyalkenyl coupling agent.
At least one of the diene blocks D'and D'' is a copolymer block derived from a mixed diene monomer, with about 65% to about 95% by weight of the monomer units incorporated from isoprene and the monomer units incorporated. About 5% to 35% by weight is from butadiene, with at least about 80% by weight of butadiene incorporated in a 1,4-configuration.
D'has a number average molecular weight of about 10,000 to about 120,000 daltons, PA has a number average molecular weight of about 10,000 to about 50,000 daltons, and D'' has a number average molecular weight of about 5,000 to about 5,000. The fuel composition according to [1], which has a number average molecular weight of about 60,000 daltons.
[3]
The fuel composition according to [1], wherein the star-shaped polyisoprene-based polymer comprises a crosslinked polystyrene core having an arm of hydrogenated polyisoprene or poly (alternate ethylene-propylene).
[4]
The fuel composition according to any one of [1] to [3], wherein the fuel composition is a diesel fuel composition.
[5]
The concentration of the VI improving additive in the fuel composition is 0.001 to 0.5% w / w, preferably 0.05 to 0.25% w / w, according to [1] to [4]. The fuel composition according to any one.
[6]
The use of a viscosity index (VI) improving additive in an automobile fuel composition for the purpose of improving the lubricity of the fuel composition, wherein the viscosity index (VI) improving additive is a star-shaped poly. Used, which is an isoprene-based polymer.
[7]
Powered by an internal combustion engine, or such engine, to which or is intended to be introduced with or intended to be introduced with a Viscosity Index (VI) Improver Additive, or an Automotive Fuel Composition containing said Viscosity Index (VI) Improver Additive. The use of a viscosity index (VI) improving additive in an automobile fuel composition for the purpose of improving the power output of a vehicle, wherein the viscosity index (VI) improving additive is a star-shaped polyisoprene system. Used, which is a polymer.
[8]
Powered by an internal combustion engine, or such engine, to which or is intended to be introduced with or intended to be introduced with a Viscosity Index (VI) Improver Additive, or an Automotive Fuel Composition containing said Viscosity Index (VI) Improver Additive. The use of a viscosity index (VI) improving additive in an automobile fuel composition for the purpose of improving the output of the vehicle and at the same time improving the lubricity of the fuel composition, wherein the viscosity index (VI) is used. ) The improving additive is a star-shaped polyisoprene-based polymer, used.
[9]
The use according to any one of [1] to [8], wherein the VI improving additive is previously dissolved in a solvent or a fuel component.
[10]
A method of operating an internal combustion engine and / or a vehicle powered by such an engine, wherein the fuel composition according to any one of [1] to [5] is introduced into the combustion chamber of the engine. Including the method.

Claims (10)

A fuel composition comprising a base fuel and at least one viscosity index (VI) improving additive, wherein the viscosity index (VI) improving additive is a star-shaped polyisoprene-based polymer. The star-shaped polyisoprene-based polymer is characterized by the following formula.
(D'-PA-D'') n-X;
In the formula, D'represents a block derived from at least one diene, PA represents a block derived from monoalkenylarene, D'' represents a block derived from a diene, and n represents a mole of arm. Represents the average number of arms per star-shaped polymer formed by the reaction of 2 mol or more of the polyalkenyl coupling agent, where X represents the nucleus of the polyalkenyl coupling agent.
At least one of the diene blocks D'and D'' is a copolymer block derived from a mixed diene monomer, with about 65% to about 95% by weight of the monomer units incorporated from isoprene and the monomer units incorporated. About 5% to 35% by weight is from butadiene, with at least about 80% by weight of butadiene incorporated in a 1,4-configuration.
D'has a number average molecular weight of about 10,000 to about 120,000 daltons, PA has a number average molecular weight of about 10,000 to about 50,000 daltons, and D'' has a number average molecular weight of about 5,000 to about 5,000. The fuel composition according to claim 1, which has a number average molecular weight of about 60,000 daltons. The fuel composition according to claim 1, wherein the star-shaped polyisoprene-based polymer comprises a crosslinked polystyrene core provided with an arm of hydrogenated polyisoprene or poly (alternate ethylene-propylene). The fuel composition according to any one of claims 1 to 3, wherein the fuel composition is a diesel fuel composition. Any of claims 1 to 4, wherein the concentration of the VI improving additive in the fuel composition is 0.001 to 0.5% w / w, preferably 0.05 to 0.25% w / w. The fuel composition according to paragraph 1. The use of a viscosity index (VI) improving additive in an automobile fuel composition for the purpose of improving the lubricity of the fuel composition, wherein the viscosity index (VI) improving additive is a star-shaped poly. Used, which is an isoprene-based polymer. Powered by an internal combustion engine, or such engine, to which or is intended to be introduced with or intended to be introduced with a Viscosity Index (VI) Improver Additive, or an Automotive Fuel Composition containing said Viscosity Index (VI) Improver Additive. The use of a viscosity index (VI) improving additive in an automobile fuel composition for the purpose of improving the power output of a vehicle, wherein the viscosity index (VI) improving additive is a star-shaped polyisoprene system. Used, which is a polymer. Powered by an internal combustion engine, or such engine, to which or is intended to be introduced with or intended to be introduced with a Viscosity Index (VI) Improver Additive, or an Automotive Fuel Composition containing said Viscosity Index (VI) Improver Additive. The use of a viscosity index (VI) improving additive in an automobile fuel composition for the purpose of improving the output of the vehicle and at the same time improving the lubricity of the fuel composition, wherein the viscosity index (VI) is used. ) The improving additive is a star-shaped polyisoprene-based polymer, used. The use according to any one of claims 1 to 8, wherein the VI improving additive is pre-dissolved in a solvent or a fuel component. A method of operating an internal combustion engine and / or a vehicle powered by such an engine, comprising introducing the fuel composition according to any one of claims 1-5 into the combustion chamber of the engine. ,Method.