WO2014029770A1

WO2014029770A1 - Additives that improve the wear resistance and lacquering resistance of diesel or biodiesel fuels

Info

Publication number: WO2014029770A1
Application number: PCT/EP2013/067311
Authority: WO
Inventors: Thomas Dubois
Original assignee: Total Marketing Services
Priority date: 2012-08-22
Filing date: 2013-08-20
Publication date: 2014-02-27
Also published as: IN2015DN01267A; EP2888344A1; CN104603246B; CN104603246A; TW201425566A; AR092373A1; FR2994695A1; EA031490B1; FR2994695B1; US20150315506A1; EA201590422A1; BR112015003674A2; TWI597358B

Abstract

The present invention relates to novel anti-lacquering additives for diesel or biodiesel fuels which have a sulphur content of less than or equal to 500 ppm by weight. These novel additives also improve the lacquering resistance of superior quality diesel or biodiesel fuels which have a sulphur content of less than or equal to 500 ppm by weight.

Description

ADDITIVES FOR IMPROVING WEAR AND LACQUER RESISTANCE OF GASOLINE OR BIOGAZOLE FUELS

The subject of the present invention is additives making it possible to limit the formation of soaps and / or varnishes in the internal parts of the fuel injection systems of engines of the (bio) diesel fuel type, that is to say in particular to increase their resistance to lacquering.

Diesel or diesel is a fuel for a diesel engine (compression engine) comprising middle distillates with a boiling point between 100 and 500 ° C.

A diesel can be a mixture of fossil-based middle distillates and biofuels.

By biofuel, we mean fuels obtained from organic matter (biomass), as opposed to fuels from fossil fuels. Examples of known biofuels include biodiesels (also known as biodiesels) and alcohols.

Biodiesel or biodiesel is an alternative to conventional diesel fuel. This biofuel is obtained from a vegetable or animal oil (including used cooking oil) transformed by a chemical process called transesterification, reacting this oil with an alcohol to obtain fatty acid esters. With methanol and ethanol, fatty acid methyl esters (EMAG) and fatty acid ethyl esters (EEAG) are obtained respectively.

Mixtures of middle distillates of fossil origin and biodiesel are referred to as the "B" followed by a number indicating the percentage of biodiesel contained in the diesel fuel. Thus, a B99 contains 99% biodiesel and 1% middle distillates of fossil origin, B20, 20% biodiesel and 80% middle distillates of fossil origin, etc.

Thus, B0 type gasoil fuels which do not contain oxygenates are distinguished from Bx type biodiesel fuels which contain x% (v / v) of vegetable oil or fatty acid esters, most often esters. methyl esters (EMHV or EMAG). When biodiesel is used alone in engines, the term fuel is termed B100.

In the remainder of this application, we will use the term (bio) diesel to identify fuels type B0 or Bx for diesel engine (compression engine).

The sulfur content of (bio) diesel fuels has been significantly reduced in many countries for environmental reasons, notably to reduce SO ₂ emissions. For example, in Europe, the maximum sulfur content of road diesel fuels is currently 10 ppm.

Processes for preparing low-sulfur diesel or diesel fuel bases, for example hydrotreatment processes in addition to reducing the sulfur content, also reduce the content of these diesel fuel gasoline bases to polycyclic aromatic compounds and in polar compounds. However, it is known that diesel or diesel fuels at low (less than 100 ppm) or very low sulfur content have a reduced ability to lubricate the engine injection system, so that for example the injection pump motor fuel can fail prematurely during the life of the engine, for example failure in high-pressure fuel injection systems, such as high-pressure rotary distributors, in-line pumps , combined pumps, with injectors.

To compensate for the loss of compounds ensuring the lubricating nature of these fuels, many lubricant additives and / or anti-wear and / or friction modifier were introduced into the marketed fuels. Their characteristics are widely described in patents EP 915944, EP 839174 and EP680506.

Commercial diesel fuels are known to meet national or supranational specifications (eg EN 590 for diesel fuels in the EU). For commercial fuels, there is no legal requirement for the incorporation of so-called performance additives (chemical compounds incorporated in fuels to improve their properties, for example detergent additives, friction reducing additives, anti-corrosion additives, antifoam additives, cold-weathering additives); oil companies and distributors are free to add or add additives to their fuels. From a commercial point of view, in the field of fuel distribution, standard or entry-level fuels, with little or no additives, are distinguished from high-quality fuels in which one or more additives are incorporated in order to improve them. performance (beyond regulatory performance).

For the purposes of the present invention, the term "high-grade fuel of diesel or biodiesel type" is understood to mean any diesel fuel or biodiesel fuel supplemented with at least 50 ppm by weight of reducing additives (s) and / or detergents and / or dispersants (s). ). FIGURES

FIG. 1 is a photograph of a high pressure direct injection diesel engine injector

FIG. 2 is a photograph of a needle of a diesel engine injector with direct injection, fouled by soap and / or lacquering deposit (lacquering)

FIG. 3 is a photograph of a nozzle of a diesel engine injector with indirect injection, fouled by coking type deposit (in English "coking")

FIG. 4 is a photograph of a needle of a direct injection diesel engine injector, fouled by soap and / or varnish deposition (in English "lacquering")

As shown in FIGS. 1 and 2, it has been found that, when using certain high quality (bio) diesel fuels, deposits 1 appeared on injection nozzle needles 2 of diesel engine injection systems, in particular those of type Euro 3 to Euro 6. Thus, the use of antiwear additives and / or friction modifier and / or anti-coking type deposits have sometimes presented resistance to lacquering unsatisfactory, or very insufficient. This results in the formation of deposit 1 generally covered by the English term lacquering which will be used in the following or under the acronym I DID (Internai Diesel Injector Deposits).

For the purposes of the present invention, the lacquering phenomenon does not concern deposits which are present outside the injection system 5 or 5 '(FIGS. 1 and 3) and which are related to coking ("coking" in English) at the origin of fouling and partial or total blockage of the injection nozzles 4 or 4 '("nozzle coking" or "fouling" in English).

Lacquering and coking are two distinct phenomena both by:

- the causes of these deposits,

- the conditions of occurrence of these deposits and,

- the place where these deposits occur.

Coking is a phenomenon that appears only downstream of a Diesel injection system.

As shown in FIG. 3, the deposits 5 'formed are characterized in that they consist of pyrolysis of the hydrocarbons entering the combustion chamber and have the appearance of carbonaceous deposits. In the case of diesel direct injection high pressure engines, it has been found that the tendency to coking is much less marked. This coking is conventionally simulated by the standard engine test CEC F098-08 DW10B, especially when the test fuel is contaminated with metallic zinc.

In the case of indirect injection engines, fuel injection is not done directly in the combustion chamber as for direct injection engines. As described for example in US4604102, there is a pre-chamber before the combustion chamber in which the fuel injection is performed. The pressure and temperature in a pre-chamber are lower than that of a combustion chamber of direct injection engines.

Under these conditions, the pyrolysis of the fuel produces carbonaceous particles which are deposited on the surface of the nozzles 4 'of the injectors ("throttling diesel nozzle in English") and clog the orifices 6 of the nozzles 4' (Figure 3). Only the surfaces of the nozzle 4 'exposed to the combustion gases present a risk of depositing coal (coking). In terms of performance, the phenomenon of coking induces a loss of engine power.

Lacquering is a phenomenon that occurs only in direct injection diesel engines and occurs only upstream of the i.e combustion chamber in the injection system.

As represented in FIGS. 1 and 2, injectors 3 of direct injection diesel engines comprise a needle 2 whose lifting makes it possible to precisely control the quantity of fuel injected at high pressure directly into the combustion chamber.

Lacquering induces the appearance of deposits 1 which appear specifically at the level of the needles 2 of the injectors 3 (Figures 1 and 2). The lacquering phenomenon is related to the formation of soap and / or varnish in the internal parts of the engine injection systems for (bio) diesel fuels. Lacquering deposit 1 can be located on the end 4 of the needles 2 of injectors 3, both on the head and on the body of the needles 2 of the fuel injection system but also throughout the control system of the Needle lift (valves not shown) of the injection system. This phenomenon is particularly noticeable for engines using high quality (bio) diesel fuels. When these deposits are present in large quantities, the mobility of the needle 2 of the injector 3 fouled by these deposits 1 is compromised. This lacquering phenomenon can eventually generate a loss of injected fuel flow and thus a loss of engine power.

In addition, unlike coking, lacquering can also cause increased engine noise and sometimes startup problems. Indeed, the parts of the needles 2 fouled by the deposits of soap and / or varnish 1 may stick to the inner walls of the injector 3. The needles 2 are then blocked and the fuel no longer passes.

There are usually two types of lacquering deposits:

1. rather whitish and powdery deposits; by analysis, it is found that these deposits consist essentially of sodium soaps

(sodium carboxylates, for example) and / or calcium (type 1 deposits);

2. organic deposits comparable to colored varnishes located on the body of the needle (type 2 deposits) With regard to type 1 deposits, the sources of sodium in Bx type biodiesel fuels can be multiple:

Transesterification catalysts for vegetable oils for the production of (m) ethyl esters of fatty acid esters such as sodium methanoate;

• sodium can also come from corrosion inhibitors used to transport petroleum products in some pipes, such as sodium nitrite;

• Finally, accidental exogenous pollution, for example via water or air, can contribute to the introduction of sodium into fuels (sodium being a very common element).

Possible sources of acids in type Bx fuels can be multiple, for example:

o Residual acids from biofuels (see standard EN14214 which sets a maximum permitted acid level)

o corrosion inhibitors used for the transport of petroleum products in certain pipes such as DDSA (dodecenylsuccinic anhydride) or HDSA (hexadecenylsuccinic anhydride) or some of their functional derivatives such as acids.

With regard to type 2 organic deposits, some publications state that they may arise in particular from reactions between deposit / dispersant reducing agents used to prevent coking (for example PIBSI-type detergents derived from polyamines) and acids ( which would be present inter alia as impurities of fatty acid esters of biodiesel).

In the publication SAE 880493, Reduced Injection Needle Mobility Caused by Lacquer Deposits from Sunflower 0/7, the authors M Ziejewski and HJ Goettler describe the phenomenon of lacquering and its adverse consequences for the operation of engines operating with sunflower oils as fuel. In the publication SAE 2008-01 -0926, Investigators into the Formation and Prevention of Internal Diesel Injector Deposits, the authors J Ullmann, M Geduldig, H Stutzenberger (Robert Bosch GmbH) and R Caprotti, G Balfour (Infineum) also describe the reactions between acids and deposit / dispersant reducers to explain type 2 deposits.

Furthermore, in SAE International Publication, 2010-01-2242, Internai Injector Deposits in High-Pressure Common Rail Diesel Engines, the authors S. Schwab, J. Bennett, Dell S., JGalante-Fox, AKulinowski and Keith T. Miller explains that the internal parts of the injectors are usually covered by a slightly colored deposit and visible to the naked eye. Their analyzes determined that most of them were sodium salts of alkenyl- (hexadecenyl- or dodecenyl-) succinic acids; sodium from desiccants, caustic water used in refineries, bottom water from tanks or seawater, and succinic diacids being used as corrosion inhibitors or present in multifunctional additive packets. Once formed, these salts are insoluble in diesel fuels with low sulfur content, and as they exist in the form of fine particles, they pass through the diesel fuel filters and are deposited inside the injectors. In this publication, the development of a motor test is described and reproduces the deposits. The publication emphasizes that only diacids generate deposits, unlike the mono carboxylic acids or the neutral esters of organic acids.

In the publication SAE International, 2010-01 -2250, Deposit Control in Diesel Fuel Injection System Modem, the authors, R. Caprotti, N. Bhatti and G. Balfour, also study the same type of internal deposits in injectors and state that the appearance of deposits is not related specifically to a type of fuel (B0 or containing EMAG (Bx)) or to a type of vehicle (light or heavy vehicles) equipped with modern engines (common rail). They show the performance of a new deposit reducer / dispersant, effective on all types of deposits (coking and lacquering). The present invention proposes additives with preventive and curative effects, making it possible to limit the deposit of soap and / or varnish in the internal parts of the injection systems, that is to say to improve the resistance to the lacquering phenomenon. engines using (bio) diesel fuel and / or (bio) Diesel, of superior quality, whose sulfur content is less than or equal to 500 ppm by weight, and which comprise at least 50 ppm by weight of reducing agent (s) of deposits and / or detergents and / or dispersant (s). These additives therefore prevent these deposits from forming (preventative), and allow when they are formed to remove them by making the injectors cleaner (curative).

These lacquering resistance problems of (bio) diesel fuels are solved by the use of at least one additive which comprises at least 50% by weight of partial ester (s) of polyols, said polyol esters comprising x ester units, y hydroxyl units and z ether units, x, y and z being integers such that x varies from 1 to 10, y ranges from 1 to 10, and z ranges from 0 to 6, preferably x varies from 1 at 10, y varies from 3 to 10, and z varies from 0 to 6.

The synthesis of partial esters of polyols is known per se; they may for example be prepared by esterification of fatty acid (s) and linear and / or branched polyols optionally comprising (hetero) rings of 5 to 6 atoms supporting hydroxyl functions. The product (s) resulting from this esterification reaction comprises a distribution in ester units, hydroxyl units and ether units such that x varies from 1 to 4, y varies from 1 to 7 and z varies from 1 to 3. Generally this type of synthesis leads to a mixture of mono-, di-, tri- and optionally tetraesters as well as small amounts of unreacted fatty acid (s) and polyols.

According to one embodiment, the polyol esters are obtained by esterification of fatty acid (s) and of linear and / or branched polyols optionally comprising heterocycles of 4 to 5 carbon atoms and an oxygen atom, supporting functions. hydroxyls.

In the context of the present invention, the polyols will be chosen from linear polyols comprising more than three hydroxyl functions and polyols comprising at least one (hetero) ring of 5 or 6 atoms, preferably heterocycles of 4 to 5 carbon atoms. and an oxygen atom, possibly substituted by hydroxyl groups, these polyols can be taken alone or in mixture.

In the remainder of the present discussion, these polyols will be referenced R in the formulations cited below.

Among the polyols R, the linear or branched hydrocarbon-chain polyols comprise at least four units represented in formula (I) below:

H - (OCH ₂ ) _p - (CHOH) _q - (CH ₂ OH) (I)

With p and q are integers, p being equal to or greater than 0, q is greater than 2, and these numbers can not exceed 10.

Among the polyols R, the linear or branched hydrocarbon-chain polyols comprise at least four units represented in formula (I I) below:

H- (OCH ₂ ) _P - (CR 1 R 2) _q - (CH ₂ OH) (II)

With p and q integers, where p is equal to or greater than 0, q is greater than 1, these numbers can not exceed 5, R1 and R2 are identical or different and represent either the hydrogen atom or a group -CH ₃ or - C ₂ H ₅ , a -CH ₂ -OH group.

Among the polyols R, some comprise at least one (hetero) ring of 4 or 5 carbon atoms and an oxygen atom, optionally substituted by hydroxyl groups and correspond to the general formula (I II) below:

O

/ \

HO-CH ₂ - (CHOH) _s - [HC- (CHOH),] (I II) with s and t integers, with when s equals 1, t is 3 and when s is zero, t is equal to 4.

Among the polyols R, some comprise at least two heterocycles of 4 or 5 carbon atoms and one oxygen atom, connected by the formation of an acetal bond between a hydroxyl function of each ring, which is optionally substituted by hydroxyl groups. Preferably, the polyols are selected from the group consisting of erythritol, xylitol, D-arabitol, L-arabitol, ribitol, sorbitol, malitol, risomalitol, lactitol, sorbitan, volemitol, mannitol , pentaerythritol, 2-hydroxymethyl-1,3-propanediol, 1,1,1-tri (hydroxymethyl) ethane, trimethylolpropane and carbohydrates such as sucrose, fructose, maltose, glucose and sucrose, preferably sorbitan.

According to a preferred variant, the partial esters of polyols are chosen from partial esters of sorbitan, preferably sorbitan monooleate, taken alone or as a mixture.

The fatty acids from which the esters according to the invention are derived can be chosen from fatty acids whose chain length varies from 10 to 24 carbon atoms and / or at least one diacid substituted by at least one polymer, for example from poly (iso) butene comprising from 8 to 100 carbon atoms. They are preferably chosen for the mono acids from stearic, isostearic, linolenic, oleic, linoleic, behenic, arachidonic, ricinoleic, palmitic, myristic, lauric and capric acids, and mixtures thereof and for the diacids among alkyl or alkenylsuccinic acids. , alkyl-or alkenylmaleic.

The fatty acids can come from the trans-esterification or saponification of vegetable oils and / or animal fats. Preferred vegetable oils and / or animal fats will be selected according to their concentration of oleic acid. For example, see Table 6.21 in Chapter 6 of the book Fuels & Engines by J.C. Guibet and E. Faure, 2007 edition, which lists the compositions of several vegetable oils and animal fats.

The fatty acids may also be derived from tall oil fatty acids (Tall Oil Fatty Acids) which comprise a major amount of fatty acids, typically greater than or equal to 90% by mass, as well as resin acids and unsaponifiables in a minor amount. , ie in quantities generally less than 10%. Preferred additives according to the invention capable of improving the lacquering resistance of high quality (bio) diesel fuels include partial esters of sorbitan.

Other preferred additives comprise at least 50% by weight of mono- and / or diester (s) of isobutylene-succinic acid and polyols according to one of the formulas I to II.

Other preferred additives comprise at least 50% by weight of mono- and / or diester (s) of monocarboxylic acids of 12 to 24 carbon atoms and polyols according to one of formulas I to III

The invention also relates to a package of additives for (biofuel) fuels containing at least one lacquering resistance additive as defined above and at least one or more other functional additives, such as deposition / dispersant reducing agents, -oxidants, combustion improvers, corrosion inhibitors, cold-strength additives (cloud point-improving, sedimentation rate, filterability and / or cold flow), dyes, demulsifiers, metal deactivators, defoamers, cetane improvers, compatibilizers, lubricity additives, anti-wear agents and / or friction modifiers, and one or more solvents or co-solvents .

The use of the additives according to the invention makes it possible to improve lacquering resistance at the fuel injectors, thus limiting the formation (deposition) of soap and / or varnish in the presence of additives such as deposit reducing agents and and / or detergent and / or dispersants. The use of these additives in (bio) diesel fuels reduces the rate of clogging and deterioration of the fuel intake or injection system, in particular on the injection pump.

The (bio) diesel fuels according to the invention (liquid fuels for compression engines) may comprise middle distillates with a boiling point of between 100 and 500 ° C .; their starting crystallization temperature TCC is often greater than or equal to -20 ° C, generally between -15 ° C and +10 ° C. These distillates are mixtures of bases which can be chosen, for example, from distillates obtained by the direct distillation of petroleum or crude hydrocarbons, vacuum distillates, hydrotreated distillates, distillates obtained from catalytic cracking and / or distillate hydrocracking under vacuum, distillates resulting from processes conversion type ARDS (atmospheric residue desulfurization) and / or visbreaking.

The (bio) diesel fuels can also contain light cuts such as distillate spirits, catalytic or thermal cracking units, isomerization alkylation units, desulfurization units, steam cracking units.

In addition, (bio) diesel fuels may contain new sources of distillates, among which may be mentioned in particular:

the heaviest cuts resulting from cracking and visbreaking processes concentrated in heavy paraffins, comprising more than 18 carbon atoms,

synthetic distillates resulting from gas transformation, such as those derived from the Fischer Tropsch process,

synthetic distillates resulting from the treatment of biomass of plant and / or animal origin, such as NexBTL, taken alone or as a mixture,

- the gas oils of coker,

alcohols, such as methanol, ethanol, butanols, ethers, (MTBE,

ETBE, ...) generally used in combination with petrol fuels, but sometimes with heavier fuels of the diesel type,

vegetable and / or animal oils and / or their esters, such as the Methyl or Ethyl Esters of Vegetable Oils or of Fatty Acids (EMHV, EEHV, EMAG, EEAG);

hydrotreated vegetable and / or animal oils and / or hydrocracked and / or hydrodeoxygenated (H OD).

These new fuel and fuel bases can be used alone or mixed with conventional petroleum distillates as fuel base (s); they generally comprise long paraffinic chains of 10 carbon atoms and more, preferably C _u to C ₃ o- In the context of the present invention, the (biofuel) fuels have a sulfur content of less than or equal to 500 mass ppm, advantageously less than or equal to 100 ppm by weight, and capable of falling to a content of less than or equal to 50 ppm mass or even less than or equal to 10 ppm mass (this is the case of diesel fuels for current vehicles whose sulfur content according to the European standard EN 590 currently in force must be less than or equal to 10 ppm mass).

The lacquering resistance additives, that is to say the formation of soap and / or varnish in the internal parts of the fuel injection systems of the (bio) diesel fuel engines according to the invention can be incorporated into the fuels. up to a value of up to 10% by mass. Advantageously, the concentration of partial esters according to the invention in the final fuel will be between 20 and 1000 ppm by weight, and preferably between 30 and 200 ppm by weight m / m, that is to say ppm by weight relative to the total mass of the fuel additive.

According to one embodiment, the compositions of (bio) diesel fuel of higher quality, comprise at least 20 ppm by weight of at least one additive according to the invention, and optionally at least one and / or more other functional additives. Preferably, the concentration of additive according to the invention in the composition, that is to say the concentration of partial esters can vary from 20 to 1000ppm by mass, and more particularly from 30 to 200ppm mass m / m.

Of the other functional additives, the lacquering resistance additives of the present invention may be used alone or in admixture with deposition and / or detergent and / or dispersant reducers, antioxidants, combustion improvers, corrosion-resistant additives (cloud point improving, sedimentation rate, filterability and / or cold flow), dyes, demulsifiers, metal deactivators, defoamers, agents improving the cetane number, and anti-wear additives, lubricity and / or friction modifiers, co-solvents, compatibilizers, etc. In a non-exhaustive manner, the other functional additive (s) may be chosen from:

❖ combustion enhancing additives; for fuels of the diesel type, mention may be made of procetane additives, in particular (but not limited to) selected from alkyl nitrates, preferably 2-ethyl hexyl nitrate, aryl peroxides, preferably benzyl peroxide. and alkyl peroxides, preferably di-tert-butyl peroxide; for petrol-type fuels, there may be mentioned additives improving the octane number; for fuels such as heating oil, heavy fuel oil, marine fuel, mention may be made of methylcyclopentadienyl manganese tricarbonyl (MMT);

❖ anti-oxidant additives, such as aliphatic, aromatic amines, hindered phenols, such as BHT, BHQ;

❖ demulsifiers or demulsifiers;

❖ anti-static additives or conductivity improvers;

❖ dyes;

❖ anti-foam additives, in particular (but not limited to) chosen, for example, from polysiloxanes, oxyalkylated polysiloxanes, and fatty acid amides derived from vegetable or animal oils; examples of such additives are given in EP 861 182, EP 663 000, EP 736 590;

❖ detergent or dispersant additives, in particular (but not limited to) selected from the group consisting of amines, succinimides, succinamides, alkenylsuccinimides, polyalkylamines, polyalkyl polyamines, polyetheramines, Mannich bases; examples of such additives are given in EP 938,535;

❖ anti-corrosion additives such as ammonium salts of carboxylic acids;

❖ chelating agents and / or metal sequestering agents, such as triazoles, disalicylidene alkylene diamines, and especially N, N 'bis (salicylidene) 1, 3-propane diamine; ❖ cold-holding additives and especially cloud-point-improving additives, in particular (but not limited to) selected from the group consisting of long-chain olefin terpolymers / (meth) acrylic ester / maleimide, and ester polymers of fumaric / maleic acids. Examples of such additives are given in EP 71 513, EP 100 248, FR 2 528 051, FR 2 528 423, EP 1 12 195, EP 1 727 58, EP 271 385, EP 291367; anti-sedimentation additives and / or paraffin dispersants in particular (but not exclusively) selected from the group consisting of polyamine-amidated (meth) acrylic acid / alkyl (meth) acrylate copolymers, alkenylsuccinimides derived from polyamines phthalamic acid and double chain fatty amine derivatives; alkyl phenol / aldehyde resins; examples of such additives are given in EP 261,959, EP 593,331, EP 674,689, EP 327,423, EP 512,889, EP 832,172; US 2005/0223631; US 5,998,530; WO 93/14178; polyfunctional cold operability additives chosen in particular from the group consisting of olefin and alkenyl nitrate polymers as described in EP 573,490;

❖ other cold-weatherability and filterability (CFI) additives, such as EVA and / or EVP copolymers;

❖ metal passivators, such as triazoles, alkylated benzotriazoles;

❖ acid neutralizers such as cyclic alkyl amines;

❖ markers, in particular markers imposed by the regulations, for example dyes specific to each type of fuel or fuel.

❖ fragrance or masking agents of odors, such as those described in EP 1 591 514;

❖ other lubricant additives, anti-wear agents and / or friction modifiers as those described above, especially (but not exclusively) selected from the group consisting of fatty acids and their ester or amide derivatives, in particular glycerol monooleate and mono- and polycyclic carboxylic acid derivatives; examples of such additives are given in the following documents: EP 680 506, EP 860 494, WO 98/04656, EP 915 944, FR 2 772 783, FR 2 772 784.

The possible other additives are generally incorporated in amounts ranging from 50 to 1, 500 ppm m / m, that is to say, mass ppm based on the total weight of the additive fuel.

These additives may be incorporated into the fuels according to any known method; for example, the additive or the mixture of additives may be incorporated in the form of a concentrate comprising the additive (s) and a solvent, compatible with the (bio) diesel fuel, the additive being dispersed or dissolved in the solvent. Such concentrates generally contain from 20 to 95% by weight of solvents.

Those skilled in the art will easily adapt the concentration of additives according to the invention as a function of the possible dilution of the additive in a solvent, the possible presence of other components resulting for example from the esterification reaction and / or other functional additives incorporated in the final fuel.

Solvents are organic solvents which generally contain hydrocarbon solvents. As examples of solvents, mention may be made of petroleum fractions, such as naphtha, kerosene, heating oil; aliphatic and / or aromatic hydrocarbons such as hexane, pentane, decane, pentadecane, toluene, xylene, and / or ethylbenzene and alkoxyalkanols such as 2-butoxyethanol and / or or mixtures thereof. hydrocarbons such as commercial solvent mixtures such as Solvarex 10, Solvarex LN, Solvent Naphtha, Shellsol AB, Shellsol D, Solvesso 150, Solvesso 150 ND, Solvesso 200, Exxsol, ISOPAR and optionally co-solvents or compatibilizers, such as 2-ethylhexanol, decanol, isodecanol and / or isotridecanol.

The invention relates to the use of at least one additive composition according to the invention incorporated in a fuel of the (bio) diesel fuel type of higher quality to improve the resistance to lacquering, ie fouling on the head and / or on the body of the needles of the fuel injection system but also throughout the system of control of the lifting of needles (valves) of the system injection, especially for engines equipped with high-pressure direct injection systems fitted to the majority of vehicles complying with the Euro 3 and most recent regulations.

According to a particular embodiment, the object of the present invention also relates to the use of a (bio) diesel fuel composition as described above, to limit the deposit of soap and / or varnish in the parts. internal engine injection systems using said composition, preferably direct injection engines, in particular high pressure direct injection engines.

The object of the present invention is also a method for limiting the deposition of soap and / or varnish in internal parts of the injection system of a motor for (diesel) fuels (Diesel engine) having a sulfur content less than or equal to 500 ppm by mass, said process comprising the combustion in said engine of a (bio) diesel fuel composition as defined above. Preferably, the method applies to direct injection engines, in particular high pressure direct injection engines.

Thus, the method according to the invention avoids and prevents the formation of soap deposits and / or varnish in the internal parts of the engine injection system, for a "keep-clean" action for maintaining the cleanliness of said engine. Advantageously, the method according to the present invention eliminates the deposit of soap and / or varnish in the internal parts of the engine injection system, for a curative "clean-up" action of cleaning the engine.

EXAMPLES

In order to test the performance of these additives according to the invention, the inventors have also developed a new reliable and robust method for assessing the sensitivity of (bio) diesel fuels, particularly those of superior quality, to lacquering. This method, unlike the methods described in the publications cited above, is not a laboratory method but is based on motor tests and is therefore of technical interest and makes it possible to quantify the effectiveness of the additives or compositions of additives against lacquering. The method of measuring lacquering developed by the inventors is detailed below:

- The engine used is a four-cylinder, 16-valve diesel engine with high-pressure Common Rail injection, with a displacement of 1,500 cm ³ and a power of 80 hp: the fuel injection pressure regulation is carried out in the high pressure part of the pump.

- The power point at 4,000 rpm is used for a period of 40 hours; the position of the injector in the chamber is lowered by 1 mm from its nominal position, which on the one hand promotes the release of thermal energy from combustion, and on the other hand brings the injector closer to the chamber of combustion.

- The injected fuel flow rate is adjusted to obtain an exhaust temperature of 750 ° C at the start of the test.

- The injection advance has been increased by 1.5 ° crankshaft compared to the nominal setting (we go from + 12.5 ° to + 14 ° crankshaft) always in order to increase the thermal stresses experienced by the nozzle of the injector.

- Finally, to increase the stresses on the fuel, the injection pressure has been increased by 10 MPa compared to the nominal pressure (that is to say from 140 MPa to 150 MPa) and the temperature is regulated. at 65 ° C at the high pressure pump inlet.

The technology used for the injectors requires a high fuel return, which promotes fuel degradation since it can be subjected to several cycles in the pump and the high pressure chamber before being injected into the combustion chamber.

A variant of the method for testing the clean-up effect (i-e cleaning of deposits of type 1 and / or type 2) has also been developed. It is based on the previous method but is separated into two parts of 20h:

• The first 20 hours are performed with a high quality B7 diesel (containing PIBSI detergent and an acidic product) known for its tendency to generate lacquering. After 8 pm, two of the four injectors are disassembled and sides to validate the amount of deposits that are present and two new injectors are then installed instead.

• The last 20 hours of the test are performed with the product to be evaluated. At the end of the test (40 hours in total), the injectors are disassembled and sides.

At the end of the test, three batches of two injectors are available:

• Lot 1: 2 injectors having seen 20h of high quality fuel known for its tendency to generate lacquering.

• Lot 2: 2 injectors having seen 20h of high quality fuel known for its tendency to generate lacquering + 20h of product to be evaluated.

• Lot 3: 2 injectors having seen 20 hours of product to be evaluated.

Expression of results

To ensure the validity of the result, various parameters are checked during the test: power, torque and fuel consumption indicate if the injector becomes dirty or if its operation is deteriorated by a formation of deposits since the operating point is the same throughout the test.

The characteristic temperatures of the various fluids (coolant, fuel, oil) make it possible to check the validity of the tests. The fuel is regulated at 65 ° C at the pump inlet, the coolant is regulated at 90 ° C at the motor output.

The flue gas values make it possible to control the ignition timing at the beginning of the test (target value of 3FSN) and to ensure that it is repeatable from one test to another.

The injectors are disassembled at the end of the test to visualize and dimension the deposits formed along the needles. The procedure for quoting the selected hands is as follows:

The scale of the notes varies from -2.5 (case of a large deposit) to 10 (case of a new needle without any deposit). The final grade is a weighted average of the notes on all the rated surfaces of the needle, ie the cone portion and the body or cylinder part of the needle. Thus the zone of the cylinder (following directly the conical part) represents 68% of the overall quotation of the needle and the zone of the cone represents 32% of the overall quotation of the needle; To facilitate the quotation, each of these two zones is divided into 4. In Figure 4, the indicated% correspond to a quarter of the surface of the needles: the overall surface weighting is therefore 17x4 = 68%.

A product performance threshold was determined in relation to this rating procedure: Result <4 = Not satisfactory, result> 4 = Satisfactory

The following examples illustrate the invention without limiting it.

Example 1 - lacquerinq resistance measures

According to the lacquering resistance measurement procedure described above, the performance of several additive packets introduced in a diesel matrix representative of the French market (B7 = diesel fuel manufactured in France containing 7% of EMAG (methyl ester) is evaluated. fatty acids) and answering ΙΈΝ 590). The details of each fuel composition tested, as well as the results obtained, are shown in Table 1.

The quantities indicated in Table 1 are mass quantities

(M / m)

Table 1

These tests demonstrate the effectiveness of the products of the invention to prevent and limit the formation of deposits of varnish types or soaps (keep-clean action), since the quotation results of the needles at the end of the test are significantly higher than the the result obtained when the fuel contains only a PiBSI capable of forming soaps on the needles of the injectors. Example 2 Lacquerinq Resistance Measures

According to the lacquering resistance measurement procedure in its clean-up version described above, the performance of several packages of additives introduced into a diesel matrix representative of the French market (B7 = diesel fuel manufactured in France containing 7% of gasoline) is evaluated. EMAG (methyl ester of fatty acids) and answering ΙΈΝ 590). The details of each fuel composition tested, as well as the results obtained, are shown in Table 2. Attention, the tests G, G 'and G "correspond to the same test, G corresponding to the result for the batch of injectors 1, G' corresponding to the result for the batch of injectors 2 and G" corresponding to the result for the batch of Injectors 3.

The quantities given in Table 2 are mass quantities (m / m)

Table 2

These tests demonstrate the curative effectiveness (clean up action) of the products of the invention, that is to say, to eliminate deposits of varnish types or soaps already formed on the needles since the rating of the set of injectors G 'is higher than that of the injector batch G (there has been a start of meaningful cleaning of the needle), and also confirms their preventive effectiveness (keep-clean action) since the rating of the set of injectors G "is significantly high .

Claims

1. Additives for limiting the deposit of soap and / or varnish in the internal parts of fuel injection systems of the (bio) diesel fuel type, having a sulfur content of less than or equal to 500 ppm, comprising at least 50% by weight of partial ester (s) of polyols, said polyol esters comprising x ester units, y hydroxyl units and z ether units, x, y and z being integers such that x varies from 1 to 10, y varies from 1 to 10, and z varies from 0 to 6.

2. Additives according to claim 1 characterized in that the polyol esters are obtained by esterification of fatty acid (s) and linear and / or branched polyols optionally comprising (hetero) rings of 5 to 6 atoms, preferably heterocycles of 4 to 5 carbon atoms and an oxygen atom, supporting hydroxyl functions.

3. Additives according to one of claims 1 and 2 characterized in that in said polyol esters, the distribution in ester units, hydroxyl units and ether units is such that x varies from 1 to 4, y varies from 1 at 7 and z varies from 1 to 3.

4. Additives according to any one of claims 1 to 3, characterized in that the polyols R are chosen from linear polyols comprising more than three hydroxyl functions and polyols comprising at least one heterocycle of 5 or 6 atoms, preferably heterocycles. of 4 to 5 carbon atoms and an oxygen atom, optionally substituted with hydroxyl groups, these polyols can be taken alone or in mixture.

5. Additives according to any one of claims 1 to 4 characterized in that R is a polyol comprising at least four units presented in formula (I) below;

H - (OCH ₂ ) _P - (CHOH) _q - (CH ₂ OH) (I) where p and q are integers, where p is greater than or equal to 0, q is greater than 2, and these numbers may not exceed 10.

6. Additives according to any one of claims 1 to 4, characterized in that R is a polyol comprising at least four units presented in the formula

(I I) below

H - (OCH ₂ ) _P - (CR 1 R 2) _q - (CH ₂ OH) (II)

where p and q are integers, where p is equal to or greater than 0, q is greater than 1, these numbers may not exceed 5, R1 and R2 are identical or different and represent either the hydrogen atom or a group -CH3 or -C2H5, a -CH20H group.

7. Additives according to any one of claims 1 to 4 characterized in that R is a polyol comprising at least two heterocycles of 4 or 5 carbon atoms and an oxygen atom, connected by the formation of a bond acetal between a hydroxyl function of each ring, which is optionally substituted with hydroxyl groups.

8. Additives according to any one of claims 1 to 4, characterized in that the partial esters of polyols are chosen from partial esters of sorbitan, preferably sorbitan monooleate, taken alone or in mixture.

9. Additives according to any one of claims 1 to 8, characterized in that the polyols R are chosen from the group comprising erythritol, xylitol, arabitol, ribitol, sorbitol, malitol, isomalitol , lactitol, sorbitan, volemitol, mannitol, pentaerythritol, 2-hydroxymethyl-1,3-propanediol, 1,1,1-tri (hydroxymethyl) ethane, trimethylolpropane and carbohydrates such as sucrose, fructose, maltose, glucose and sucrose, preferably sorbitan.

10. Additives according to any one of claims 1 to 9 characterized in that the partial esters of polyols are obtained by reaction of the polyols with at least one fatty acid chain length ranging from 10 to 24 carbon atoms and / or at least one diacid substituted with at least one polymer, for example poly (iso) butene comprising from 8 to 100 carbon atoms.

11. Additives according to claim 10, characterized in that the partial esters of polyols are chosen from the group consisting of monoesters or diesters obtained from mono acids chosen from stearic, isostearic, linolenic, oleic, linoleic and behenic acids. arachidonic, ricinoleic, palmitic, myristic, lauric, capric, and mixtures thereof and / or diacids selected from alkyl- or alkenylsuccinic, alkyl-or alkenylmaleic acids.

12. Use of an additive as defined in any one of claims 1 to 1 1 to limit the deposition of soap and / or varnish in the internal parts of the fuel injection systems of engines for (bio) diesel fuel having a sulfur level of less than or equal to 500 ppm by mass.

13. Use according to claim 12, characterized in that said additive is intended to be incorporated in a fuel (bio) diesel fuel for said engine, preferably at a concentration of at least 20 ppm mass.

14. Use according to one of claims 12 and 13, characterized in that the engines are direct injection engines.

15. Compositions of (bio) diesel fuel having a sulfur content of less than or equal to 500 ppm by weight, containing at least one additive as defined in any one of claims 1 to 1 1, and possibly at least one or more other functional additives, such as deposit reducing agents and / or detergents and / or dispersants, antioxidants, combustion improvers, corrosion inhibitors, cold-holding additives, dyes, demulsifiers, metal deactivators, defoamers, cetane improvers, lubricant additives, antiwear agents and / or friction modifiers, and co-solvents and compatibilizers.

16. (Bio) gasoil fuel compositions according to claim 15 containing up to 10% by weight of one or more additives as defined in any one of claims 1 to 1 1.

17. Compositions of high quality (bio) diesel fuel, containing at least 50 ppm by weight of deposit / detergent / dispersant reducer (s) and containing at least 20 ppm by weight of an additive as defined in any of claims 1 to 1 1 and optionally at least one or more other functional additives, such as antioxidants, combustion improvers, corrosion inhibitors, cold-holding additives, dyes, demulsifiers, metal deactivators, defoamers, cetane index improvers, lubricant additives, anti-wear agents and / or friction modifiers, and co-solvents and accounting agents.

18. Fuel (organic) gas oil compositions according to any one of claims 15 to 17 having a concentration of mono- and di-ester (s) ranging from 20 to 1 000 ppm by weight, and preferably from 30 to 200 ppm. Massive m / m.

19. Use of a composition as defined in any one of claims 15 to 18, for limiting the deposition of soap and / or varnish in the internal parts of the engine injection systems using said composition.

20. Use according to claim 19, characterized in that the engines are direct injection engines.

21. A method for limiting the deposition of soap and / or varnish in internal parts of the injection system of a motor for (bio) diesel fuel (diesel engine) having a sulfur content of less than or equal to 500 ppm by mass, said method comprising combustion in said engine of a composition as defined in any one of claims 15 to 18.

22. The method of claim 21, characterized in that the engine is a direct injection engine.

23. Method according to one of claims 21 and 22, characterized in that avoids and prevents the formation of soap deposit and / or varnish in the internal parts of the engine injection system, for an action " keep-clean "maintaining the cleanliness of said engine.

24. Method according to any one of claims 21 to 23, wherein removing the deposit of soap and / or varnish in the internal parts of the engine injection system, for a curative action "clean-up" cleaning of the motor.