FR2583057A1 - Additive formulations for diesel fuels and the diesel fuels containing them - Google Patents

Abstract

Additive formulations for diesel fuels, with a synergistic effect of reduction in the formation of deposits, in particular on the injectors of diesel engines with indirect injection. These formulations comprise: - from 5 to 95 % by weight of a terpolymer containing from 10 to 94 mol% of units A derived from at least one polymerisable ester of a monocarboxylic acid; - from 3 to 65 mol% of units B derived from at least one unsaturated alpha , beta -dicarboxylic compound in the form of ester, amide or imide and from 3 to 40 mol% of units C derived from diisobutylene; and - from 95 to 5 % of at least one organic nitrate. These formulations are employed, for example, at a concentration of 0.1 to 25 kg/m<3> in diesel fuels.

Description

The present invention relates to additive formulations which, when added to diesel fuels, significantly reduce the tendency of the latter to form deposits, in particular on the injectors of indirect injection diesel engines.

The very significant development of passenger vehicles equipped with rapid indirect injection diesel engines observed over the past ten years and which, in all likelihood, should increase over the next few years, has led refining manufacturers, forced to satisfy the request, to use techniques for converting the heavy fractions of crude oils (catalytic cracking - hydrocracking - coking - visbreaking.) from increasingly heavy crudes. But the addition of such products to direct distillation gas oils leads to a lower quality gas oil "pool".

In addition, the current trend of improving engine performance and strengthening anti-pollution measures is forcing automakers to make technological feats that make these engines even more sensitive to fuel quality. The degradation of the quality of diesel fuels manifests itself in particular by a decrease in the cetane number and by an increase in the ability to form deposits in the combustion chambers and on the injectors.

The nuisance caused by the gradual carbonization of the injectors, which disrupts the normal injection and combustion processes, is manifested by unstable operation of the vehicle, by vibrations, by an increase in noise at idle at low load and at low speed. , by cold starting difficulties, by higher emissions of unburnt hydrocarbons, carbon monoxide, particles, all of this constituting manifestations little appreciated by the user.

The invention provides formulations of fuel additives
Diesel which significantly reduce the aforementioned drawbacks.

In general, these formulations comprise (1) at least one terpolymer consisting of units derived from at least one polymerizable monocarboxylic acid ester, at least one unsaturated dicarboxylic compound X, 0 and diisobutylene and relating to at least one unsaturated dicarboxylic compound X, 0 and diisobutylene. at least part of the dicarboxylic units of the ester, amide or imide groups; (2) at least one organic nitrate and optionally (3) at least one complexing agent for metals as defined below.

One of the characteristics of the invention relates to the synergistic effect observed when the terpolymers (1) are combined with organic nitrates (2) in a diesel fuel; this synergistic effect is manifested in particular by a noticeable reduction in the tendency of diesel fuel to form deposits on engine injectors.
Indirect injection diesel; such a large decrease could not be predicted by considering separate effects of components (1) and (2).

dans lesquelles R1 représente un atome d'hydrogène ou-un radical méthyle et R 2 représente un radical alkyle de 1 à 30 atomes de carbone ou un mélange de tels radicaux (B) des motifs dérivant d'au moins un composé cc'p ~aicarboxylisue et répondant à l'une des formules générales

dans lesquelles R3 et R4 , identiques ou différents, représentent un atome d'hydrogène ou un radical méthyle, X et Y, identiques ou différents sont choisis parmi les groupes -OH,-OR2,OR5, -NH2 et -NHR5, R2 étant défini comme précédemment et R5 représentant un radical organique monovalent dérivé d'un composé renfermant au moins une fonction hydroxyle et/ou au moins une fonction amine ; et (C? des motifs répondant à la

The terpolymers considered as constituents (1) of the formulations of the invention comprise the following three types of units (A) units derived from at least one acrylic ester and / or from at least one vinyl ester and corresponding to the general formulas

in which R1 represents a hydrogen atom or a methyl radical and R 2 represents an alkyl radical of 1 to 30 carbon atoms or a mixture of such radicals (B) of units derived from at least one compound cc'p ~ aicarboxylisue and meeting one of the general formulas

in which R3 and R4, identical or different, represent a hydrogen atom or a methyl radical, X and Y, which are identical or different, are chosen from the groups -OH, -OR2, OR5, -NH2 and -NHR5, R2 being defined as above and R5 representing a monovalent organic radical derived from a compound containing at least one hydroxyl function and / or at least one amine function; and (C? of the reasons answering the

<tb> formula .:
<tb><SEP> CH2 <SEP> - <SEP> (Uf.
<tb>

<SEP> Ca <SEP> c
<tb><SEP> CH2
<tb><SEP> H3C <SEP> - <SEP> C <SEP> - <SEP> CH3
<tb><SEP> CH3
<tb> derived from diisobutylene.

The respective proportions of the units (A), (B) and (C) contained in the terpolymers considered in the invention are generally from 10 to 94%, preferably from 40 to 80% by moles for the units (A), from 3 to 65%, preferably from 10 to 40% by moles for the units (B) and from 3 to 40%, preferably from 10 to 30% by moles for the units (C). By the way, there. It is advantageous for the content of units (B) derived from an ethylenically unsaturated dicarboxylic compound to be at least equal to that of the units (C) derived from diisobutylene.

Their number average molecular weight is generally 500 to 250,000.

The terpolymers considered in the invention can be prepared according to conventional methods of radical polymerization, for example in the presence of an initiator of azobisisobutyronitrile or peroxide type, in bulk or in solution in a hydrocarbon solvent, such as, for example, cyclohexane. , isooctane, dodecane, benzene, toluene, xylene, diisopropylbenzene, tetrahydrofuran or dioxane. Relatively high boiling point hydrocarbon cuts, such as kerosene, gas oil, or light lubricating mineral oil, will preferably be used.

The operation is generally carried out under atmospheric pressure and at a temperature not exceeding 1400C, preferably between 60 and 1200C.

Appropriate proportions of the various monomers are used in this first step; in general, a molar proportion of compound X, j3 -dicarboxylic containing ethylenic unsaturation (for example maleic anhydride) at least equal to the molar proportion of diisobutylene is used.

dans laquelle R1 est un atome d'hydrogène ou un radical méthyle et R2 est un radical alkyle de 1 à 30 atomes de carbone, de préférence de 4 à 22 atomes de carbone.To obtain terpolymers comprising ester, amide or imide groups in at least part of the units (B), the reaction mixture resulting from the first step is reacted in a second step with a (poly) amine and / or (poly ) hydroxylated at a temperature generally between 80 and 1600C (in the possible presence of a small amount of an acid soluble in a hydrocarbon medium when the compound is essentially of (poly) hydroxyl type
The unsaturated esters from which the units (A) are derived may consist more particularly of compounds of general formula

in which R1 is a hydrogen atom or a methyl radical and R2 is an alkyl radical of 1 to 30 carbon atoms, preferably 4 to 22 carbon atoms.

As examples of such compounds, there may be mentioned mainly acrylates and methacrylates of methyl, propyl, butyl, 2-ethylhexyl, decyl, dodecyl, hexadecyl, octadecyl, eicosyl and docosyl. Mention may also be made of acrylates and methacrylates of industrial cuts of alcohols containing on average 12 carbon atoms, 18 carbon atoms or from 20 to 22 carbon atoms.

dans laquelle R1 est de préférence un atome d'hydrogène et R2 est un radical alkyle de 1 à 30 atomes de carbone, de préférence de 1 à 22 atomes de carbone.The unsaturated esters from which the units (A) are derived can also consist of compounds of general formula

wherein R1 is preferably a hydrogen atom and R2 is an alkyl radical of 1 to 30 carbon atoms, preferably 1 to 22 carbon atoms.

As an example of such vinyl esters, mention will mainly be made of vinyl acetate.

The ethylenically unsaturated 3-dicarboxylic monomers from which the units (B) are derived are chosen more particularly from anhydrides and maleic and citraconic acids, and fumaric and mesaconic acids.

The (poly-) hydroxylated and / or (poly-) amino compound used in the second step can be chosen, for example, from dimethylamino -3 propylamine, triethylene tetramine, tetraethylenepentamine, amino -2 pyridine, diethylethanolamine, diethanolamine, cyano- l guanidine, trimethylolpropane, glycerol, pentaerythritol, and linear aliphatic monoalcohols.

According to another particular mode of synthesis of the terpolymers considered in the invention, it is possible to carry out the radical terpolymerization between at least one polymerizable ester of monocarboxylic acid, at least one compound X, 0 dicarboxylicue with esterified, amidified or imidified ethylenic unsaturation. prior and diisobutylene.

The ethylenically unsaturated dicarboxylic compound α;, ss can then be chosen from derivatives containing ester or amide functions of maleic, fumaric, citraconic and mesaconic acids and derivatives containing N-substituted imide functions, these maleic and citraconic anhycrides.
The terpolymers used in the invention are advantageously presented in the form of concentrated solutions, for example, from 10 to 60 parts by mass, preferably about 40 parts by mass dissolved in 90 to 40 parts by mass, preferably about 60 parts by mass. solvent (with or without other additives).

The second constituent of fuel additive formulations
Diesel of the invention consists of at least one organic nitrate (or nitrate ester) which can be chosen from a wide variety of compounds.

The nitrate esters considered may consist of aliphatic or cycloaliphatic nitrates in which the aliphatic or cycloaliphatic group is saturated or not; they contain from 1 to about 12 carbon atoms and can optionally be substituted by at least one group containing one or more oxygen atoms.

The most characteristic nitrate esters which can be used are methyl, ethyl, propyl, allyl, butyl, isobutyl, secondary butyl, tertiary butyl, amyl, isoamyl, amyl-2, amyl-3, hexyl, heptyl, heptyl-2 , octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, cyclopentyl, cyclohexyl, methylcyclohexyl, cyclododecyl, 2-ethoxyethyl, tetrahydrofuranyl and mixtures thereof; preferably amyl and octyl nitrates.

so that a particularly increased effect of reducing the formation of deposits on the injectors of diesel engines is observed, it is advantageous that the constituents (1) and (2) of the formulations of the invention are to each other in a weight ratio of 5/95 to 95/5 or preferably from 10/90 to 90/10, the overall concentration of said formulation (constituents (1) + (2)) being, relative to diesel fuel, from 0.1 to 25 kg / m3 and preferably from 0.3 to 8 kg / m3.

The formulations of the invention can also contain a constituent (3) playing the role of metal deactivator and chosen for example from salicylidene-0 aminophenol, disalicylidene ethylenediamine, and disalicylidene propylenediamine, preferably N, N 'disalicylidene-1 , 2 diaminopropane. This metallic deactivator (3) is used at concentrations of between 0.1 and 15 g / m3 of fuel, preferably between 0.5 and 10 g / m3.

The following examples illustrate the invention without limiting it.

In Examples 1 to 11 which follow, the preparation of various polymeric compounds serving as component (1) in additive formulations according to the invention is described.

Example 1 (a) A solution of 22.5 g (66.5 x 10 moles) of steth methacrylate
aryl, 110 g (89.2 x 10 3 mole) of diisobutylene and 7.5 g (76.5 x 10 3 mole) of maleic anhydride in 80 cm of toluene is heated.
fairy up to 900C. A solution containing 0.3 g of azobisisobutyro
nitrile in 20 cm3 of toluene is added slowly (speed of ad
dition: 10 cm3 / h) and the mixture is stirred at 900C for 4 hours.

The reaction mixture is then cooled and then mixed with
excess methyl alcohol; the precipitate obtained is separated
by filtration and dried under reduced pressure to cons
so much. The resulting terpolymer contains about 54 mol%
of stearyl methacrylate, 20 mol% of diisobutylene and
26 mol% of maleic anhydride; its molecular mass in name
bre is 10,200.

(b) 13 g of the polymer obtained in step (a) are dissolved in (500 cm3
mineral oil 200 Neutral Solvent and 2 g of dimethylaminopropyl
amine are added; the mixture is then stirred for 4 hours
at 1500C. The infrared analysis of the resulting solution shows the
disappearance of the adsorption band corresponding to the -l bonds
C = 0 of anhydride type initially located at about 1775 cm
in parallel we observe the appearance of a band, around
-î
1705-1695 cm, attributable to C = 0 bonds of the imide type.

Example 2
A solution of 14 g (41.4 x 10 3 mole) of stearyl methacrylate, 6 g (32.6 x 10-3 mole) of 2-ethylhexyl acrylate, 7 g (62.5 x mole) of diisobutylene and 10 g (10.2 x 10 mole) of maleic anhydride in 100 cm3 of mineral oil 100 Neutral Solvent is heated at 80 C for 2 hours in the presence of 0.4 g of azobisisobutyronitrile, and then at 1000 C for 2 hours. 1.5 g of tetraethylenepentamine are then added to the medium which according to stirring at 1400C for 2 additional hours.

Example 3
A mixture of 13 g (51.2 x 10-3 mole) of lauryl methacrylate, 11 g (32.5 x 10-3 mole) of stearyl methacrylate, 6 g (53.5 x 10-3 mole) of diisobutylene and 8 g (81.6 x 10-3 mole) of maleic anhydride
3 is dissolved in 140 cm of toluene. 0.8 g of dicumyl peroxide is added, then the mixture is heated at 1200C for 2 hours.

After adding 8 g of diethanolamine, heating is continued at 100 ° C. for 4 hours. An additive concentrate in mineral oil is prepared by adding 50 cm of 100 Neutral mineral oil.
Solvent, the toluene then being evaporated under reduced pressure to constant weight
Example 4
A mixture of 40 g (12.3 x 10 mole) of stearyl acrylate, 10 g (70.4 x 10 3 mole) of butyl methacrylate, 5 g (0.05 mole) of methyl methacrylate, 25 g (22.3 x 10 mole) of diisobutylene and 30 g (30.6 x 10-2 mole) of maleic anhydride is heated at 900C for 3 hours, in the presence of 1.1 g of benzoyl peroxide, then at 1100C for 2 hours. The mixture is then evaporated under reduced pressure at 110 ° C. for 1 hour, so as to remove the residual monomers.

The residue is then dissolved, with stirring at 100 ° C., in 350 cm3 of a 200 N lubricating oil. 28 g of dimethylaminopropylamine are added thereto and the solution is stirred at 1500 ° C. for 4 hours.

Example 5 (a) A solution of 51 g (15.1 x 10-2 2 moles) of stea methacrylate
ryle, 37 g (14.5 x 10 2 moles) of lauryl methacrylate and 1.6 g
3
of azobisisobutyronitrile in 200 cm of dioxane is added
in 4 hours to a solution of 33 g (29.4 x 10 mole) of diisobu
tylene and 40 g (40.8 x 10-2 mole) of maleic anhydride in
200 cm of dioxane at 700C. Heating to this temperature
is maintained for an additional 4 hours.

3 (b) 400 cm of 100 Neutral Solvent mineral oil is added to the
solution prepared in step (a), and dioxane is distilled
under reduced pressure to constant weight. We then add
80 g of trimethylolpropane and 1.2 g of paratoluene sulfo acid
nic, and the mixture is heated at 1500C for 4 hours.

The infrared analysis of the solution obtained shows the dispari
tion of absorption at the frequency corresponding to the connections
C = 0 of the anhydride groups; on the other hand, we observe the appar
tion of an absorption frequency corresponding to the new
C = O bonds formed, among which we locate around 1725
1735 cm3 the C = O bonds of polymethacrylates.

Example 6
A mixture of 11 g (110 x 10 mole) of methyl methacrylate, 62 g (244 x 10 mole) of lauryl methacrylate, 27 g (79.8 x 10 3 molej of stearyl methacrylate, 6 g (61.2 x 10 3 mole) male anhydride
-3 ic and 6.7 g (59.8 x 10 mole) of diisobutylene, is dissolved in
382 cm of 100 Neutral Solvent mineral oil, then heated to 1000C.

Gradually added with stirring 0.386 g of azobisibutyronitrile over 4 hours, then heating is continued at 1200C for 1 hour. 6 g (58.8 x 10 3 mol) of dimethylaminopropylamine are then added to the mixture, which is maintained for 4 hours at 1400C.

A brown-red additive solution is thus obtained.

Example 7 (a) 0.5 g of azobisisobutyronitrile is added to a solution of 32 g
(9.87 x 10 2 mole) stearyl acrylate, 11 g (11.22 x 10 2 mole)
maleic anhydride and 10 g (8.92 x 10-2 2 moles) of diisobutylene
3
in 250 cm of toluene, then the mixture is stirred at 900C for
6 hours.

(b) 3.8 g (3.7 x 10 2 moles) of dimethylaminopropylamine are added
3
at 100 cm from the solution of step (a), then the mixture is
stirred at 1500C for 4 hours. The terpolymer is then isolated
by precipitation with methyl alcohol. The infrared spectrum
of the modified polymer thus obtained shows the disappearance of
absorption band attributable to C = 0 bonds of the -l anhydride type
initially located around 1775 cm, whereas appa
would have a new absorption band around 1705-1695
-l
cm due to the formation of C = 0 bonds of the imide type.

Example 8
A solution consisting of 1.2 g of dicumyl peroxide 3 and 20 cm of diisopropylbenzene is added over 2 hours to a solution of 66 g (20.37 x 10 mol) of stearyl acrylate, 18 g (9 , 78 x 10-2 mole) of 2-ethylhexyl acrylate, 12 g (10.71 x 10-2 2 mole) of diisobutylene and 31 g (13.59 x 10-2 mole) of dibutyl maleate in 500 cm3 of diisopropylbenzene, heated to 1200C; the mixture obtained is maintained at this temperature for 4 hours.

The product obtained, after precipitation with methyl alcohol and then drying, has a number-average molecular mass of approximately 7000.

Example 9
A mixture of 24 g (21.43 x 10 mole) of diisobutylene and 40 g (21.97
-2 x 10-2 mol) of maleimide (obtained by reaction of maleic anhydride with dimethylaminopropylamine) in 500 cm3 of gas oil (distillation range: 150-3700C), is heated to 900C; we add pro
3 gradually 500 cm of a solution in the same diesel of 32 g (9.87
-2 -2 x 10 mole) of stearyl acrylate, 50 g (20.83 x 10 2 mole) of lauryl acrylate and 1.2 g of azobisisobutyronitrile. The desired additive is obtained after 4 hours of stirring at 900C.

Example 10
1 g of benzoyl peroxide is added to a solution of 15 g (10.56 x 10-2 mole) of butyl methacrylate, 18 g (9.78 x 10-2 mole) of 2-ethylhexyl acrylate , 20 g (17.86 x 10-2 2 moles) of diisobutylene and 40 g (40.82 x 10 2 moles) of maleic anhydride in kerosene.

The mixture is gradually heated at 700C for 2 hours, then at 900C for 2 hours and, finally, at 110C for 2 hours.

Then gradually added 216 g (0.8 mol) of "ALFOL 18" (cut of saturated linear monoalcohols containing on average 18 carbon atoms), and 2.8 g of paratoluene sulfonic acid; the additive, which results from the almost complete esterification of the anhydride groups by Alfol, is obtained after 4 hours of stirring at 1500C.

Example 11
A mixture of 32 g of C20 22 acrylates, 4 g of maleic anhydride, 4 g of diisobutylene and 40 cm3 of xylene is stirred at 850 ° C. for 4 hours in the presence of 0.8 g of azobisisobutyronitrile; after addition of 4 g of dimethylaminopropylamine, the desired additive solution estobtenue.after 2 hours of heating at 1400C.

Example 12
To show the effect of formulations according to the invention on the tendency to carbonate of the injectors of indirect injection compression ignition engines, a motorized passenger vehicle is used.
Commercial diesel operating on a scale test cycle, which will be described later.

The level of carbonization of the injectors as well as the effects of this carbonization are determined through the following measurements and tests: air flow rates through the injectors, emissions of carbon monoxide, unburnt hydrocarbons and particles during a standardized urban cycle carried out on a bench roller, engine noise, examination of deposits on injectors with a scanning electron microscope.

The vehicle used for these tests is a Peugeot 305 SRD 3 model from 1984 equipped with a 4-cylinder diesel engine with 1905 cm of displacement of the XUD type with Ricardo Comet V pre-chamber injection.

This engine is equipped with Bosch injection equipment, type pump
VE 4/9 and DNOSD 256 type injectors.

The base fuel used for these tests is an American type diesel fuel with a cetane number measured on a C.F.R. engine of 42.

Mass spectrometry analysis carried out on this gas oil gives a mass composition of 65% saturated hydrocarbons and 35% aromatic hydrocarbons.

The distillation curve (NF M 07-002) is as follows

<tb> t <SEP>% <SEP> distilled <SEP> | <SEP> Temperature <SEP> C <SEP>
<tb> Initial <SEP> point <SEP> 1 <SEP><SEP> 179 <SEP><SEP> 1 <SEP>
<tb> 15 <SEP> 199
<tb><SEP> 10 <SEP> 208 <SEP>
<tb> 20 <SEP> 219
<tb> 30 <SEP> 231
<tb><SEP> 40 <SEP> 1 <SEP><SEP> 243 <SEP> I
<tb> 50 <SEP> 256
<tb> 60 <SEP> 267
<tb> 70 <SEP> 278
<tb> 80 <SEP> 290
<tb> 90 <SEP> 309
<tb> 95 <SEP> 325
<tb> I <SEP> 95 <SEP> I <SEP> 354 <SEP>
<tb>{<SEP> End point <SEP><SEP> 1 <SEP> 354 <SEP> 1 <SEP>
<tb>
distillate 99% volume
Residue 1% volume
Loss O
Before each test, the fuel supply and return circuit, the fuel filter jar and the tank are purged and cleaned, the circuit is filled with the test fuel and the vehicle performs at least 200 kilometers with injectors. rinse aid to remove all traces of old product that may remain in the pump and other places.

New BOSCH DNOSD 256 injectors are fitted with new sealing washers and flame arresters as well. The fuel filter is replaced with a new one.

The test consists of running the vehicle on a chassis dynamometer capable of reproducing the operation of the vehicle on the road. This bench is adjusted so as to absorb a power representing the aerodynamic resistance and the rolling resistance, for the vehicle used, the forward resistance varies according to the square of the speed with 1.7 kW absorbed at 50 km / h . The inertia due to the mass of the vehicle here 1134 kg is also simulated.

A test day includes - two operating conditions at stabilized speed represented
both road traffic and motorway traffic; and - urban traffic cycles corresponding to the ECE standard
N 15.

Stabilized gears are achieved on the 3rd gear of the gearbox and maintained by an automatic device;
The urban cycles are carried out by a driver and are used to assess the carbonization of the injectors by measuring the emissions of unburned hydrocarbon carbon monoxide and particles present in the exhaust gases. This measurement is made in accordance with the EPA (Environmental Protection Agency) regulations in the USA and the European standard in preparation.

One test represents several thousand kilometers divided into test days, the sequence of which is shown in the following table

<tb><SEP> Phase <SEP> Speed <SEP> Speed <SEP> Load <SEP> Duration <SEP> Dist.
<tb>

<SEP> (km / h) <SEP> (rpm) <SEP> (kW) <SEP> (min) <SEP> (km)
<tb><SEP> 1 <SEP> cycle <SEP> ECE <SEP> variable <SEP> variable <SEP> 13 <SEP> 4.05
<tb><SEP> 2 <SEP> 90 <SEP> 4345 <SEP> 9.9 <SEP> 30 <SEP> 45
<tb> 3 <SEP> cycle <SEP> ECE <SEP> variable <SEP> variable <SEP> 13 <SEP> 4.05
<tb><SEP> 4 <SEP> 50 <SEP> 2415 <SEP> 1.7 <SEP> 30 <SEP> 25
<tb> 5 <SEP> cycle <SEP> ECE <SEP> variable <SEP> variable <SEP> 13 <SEP> 4.05
<tb><SEP> 6 <SEP> 50 <SEP> 2415 <SEP> 1.7 <SEP> 30 <SEP> 25
<tb><SEP> 7 <SEP> 90 <SEP> 4345 <SEP> 9.9 <SEP> 30 <SEP> 45
<tb><SEP> 8 <SEP> 50 <SEP> 2415 <SEP> 1.7 <SEP> 30 <SEP> 25
<tb><SEP> 9 <SEP> 90 <SEP> 4345 <SEP> 9.9 <SEP> 30 <SEP> 45
<tb><SEP> 10 <SEP> 50 <SEP> 2415 <SEP> 1.7 <SEP> 30 <SEP> 25
<tb><SEP> 11 <SEP> 90 <SEP> 4345 <SEP> 9.9 <SEP> 30 <SEP> 45
<tb><SEP> 12 <SEP> cycle <SEP> ECE <SEP> variable <SEP> variable <SEP> 13 <SEP> 4.05
<tb><SEP> 13 <SEP> 50 <SEP> 2415 <SEP> 1.7 <SEP> 30 <SEP> 25
<tb> 14 <SEP> cycle <SEP> ECE <SEP> variable <SEP> variable <SEP> 13 <SEP> 4.05
<tb><SEP> 15 <SEP> 90 <SEP> 4345 <SEP> 9.9 <SEP> 30 <SEP> 45
<tb>
For each phase at stabilized speed, a series of engine operating parameters, such as intake, diesel, water and oil temperatures, is checked.

At the end of the test, the vehicle is taken to a quiet and clear place to measure the noise at idling when the engine is hot.

The microphone is placed in the axis 4 m in front of the vehicle and 1 m from the ground. The engine cover remains closed.

A measurement is also made in the passenger compartment, in place of the driver. After these operations, the injectors are removed, taking all the necessary precautions not to disturb the deposits which have formed. Air flow measurements through the injectors are made for different needle lifts in accordance with ISO 4010-1977.

The deposits on the injector bodies and needles are then observed and photographed under a scanning electron microscope, which makes it possible to define a scaling rate.

Four experiments are carried out using the following fuels
A1: Base fuel only.

B1: Base fuel containing 2.5 kg / m3 of iso nitrate
octyl
C1: Base fuel containing 8.33 kg / m3 of prepared additive
according to example 2 (30% of active material - 70% of oil
mineral 100 Neutral Solvent) i.e. 2.5 kg / m3 of material
active.

D1: Base fuel containing 2 kg / m3 of iso nitrate
octyl and a proportion of additive prepared according to the example
3
3 corresponding to 0.5 kg of active material / m3.

The measurements making it possible to evaluate the effectiveness of the additive formulations studied are as follows: * Measurement of the air flow rate (standard ISO 4010-1977) in cm3 / min passing
through injectors for different needle lifts (medium
ne for the 4 injectors after dismantling at the end of the test)
table 1 * Emissions of pollutants on the ECE NO 15 cycle expressed in g / test
table 2 * Measurement of noise at idle when the engine is hot, expressed in decibels:
table 3
TABLE 1

<tb> TABLE <SEP> 1
<tb> Needle lift <SEP><SEP> (mm)
<tb><SEP> Fuel <SEP> 0.1 <SEP> 0.2 <SEP> 0.3
<tb><SEP> A1 <SEP> 15 <SEP> 30 <SEP> 80
<tb><SEP> B1 <SEP> 18 <SEP> 30 <SEP> 90
<tb><SEP> C1 <SEP> 60 <SEP> 120 <SEP> 230
<tb> D1 <SEP> 65 <SEP> 130 <SEP> 245
<tb>
The measured air flow (hence the diesel flow) being proportional to the reduction in the effective section of the "injectors, examination of Table 1 shows that at the end of the test, the injectors having operated with the fuel D1, containing a formulation of additives according to the invention, are much less calcified than the injectors which have operated with the base fuel (A1) or with the fuels containing the separate additives (fuels B1 and C1).

Examination of the deposits with a scanning electron microscope leads to the same conclusions.

This has consequences in terms of pollutant and noise emission measurements, confirmed by the results presented in Tables 2 and 3 below.

TABLE 2

<tb> CO <SEP> HC <SEP> Particles
<tb> Fuel <SEP> d <SEP> f <SEP> d <SEP> f <SEP> d <SEP> f
<tb> A1 <SEP> 11 <SEP> 12 <SEP> 6 <SEP> 11 <SEP> 0.65 <SEP> 1.50
<tb><SEP> B1 <SEP> 9 <SEP> 11 <SEP> 2.5 <SEP> 9 <SEP> 0.35 <SEP> 1.30
<tb> C1 <SEP> 10 <SEP> 10 <SEP> 4 <SEP> 5 <SEP> 0.45 <SEP> 0.40
<tb> D1 <SEP> 8 <SEP> 7 <SEP> 2 <SEP> 2.5 <SEP> 0.30 <SEP> 0.30
<tb> d = start of test f = end of test.

TABLE 3

<tb> t <SEP> t <SEP>
<tb> Exterior <SEP> Interior
<tb> Fuel <SEP> d <SEP> f <SEP> d <SEP> f
<tb><SEP> A1 <SEP> 65 <SEP> 67 <SEP> 56 <SEP> 60
<tb> B1 <SEP> 62.5 <SEP> 64.3 <SEP> 53.5 <SEP> 55.5
<tb><SEP> C1 <SEP> 64.5 <SEP> 65 <SEP> 56 <SEP> 57
<tb> D1 <SEP> 62.2 <SEP> 63.4 <SEP> 53.5 <SEP> 54.8
<tb>
d = start of test, f = end of test.

There is a noticeable reduction in the emission of pollutants and fruit at the start of the test, but also a greater stability of the measurements as a function of the kilometers traveled with the fuel D containing the additive formulation according to the invention compared to the fuel alone. (A1) and fuels containing the two separate additives (fuels B1 and C1).

Example 13
Another series of experiments is carried out using the following fuels
A2: Base fuel only, identical to A1 fuel.

B2: Base fuel containing 2 kg / m3 of iso nitrate
octyl.

C2: Base fuel containing 13.7 kg / m3 of the product of
Example 9 (ie 2 kg of active material / m3).

D2: Base fuel containing 1.5 kg / m3 of iso nitrate
octyl and a proportion of additive prepared according to ex
Example 9 corresponding to 0.5 kg of active material / m3.

The measured performances are reported in tables 4, 5 and 6 below.
TABLE 4
Average characteristics, flow (cm3 / min)
needle lift (mm) at the end of the test

<tb> Needle lift <SEP><SEP> (mm)
<tb> Fuel <SEP> 0.1 <SEP> 0.2 <SEP> 0.3
<tb> A2 <SEP> 13 <SEP> 30.5 <SEP> 77
<tb><SEP> B2 <SEP> 15.5 <SEP> 29 <SEP> 79
<tb> C2 <SEP> 58 <SEP> 157 <SEP> 226
<tb> D2 <SEP> 63 <SEP> 128 <SEP> 242
<tb>
TABLE 5
Emissions on ECE 15 cycle in g / test

<tb> Emissions <SEP> on <SEP> cycle <SEP> ECE <SEP> 15 <SEP> in <SEP> g / test
<tb> CO <SEP> HC <SEP> Particles
<tb> Fuel <SEP> d <SEP> f <SEP> d <SEP> f <SEP> d <SEP> f
<tb> A2 <SEP> 10 <SEP> 11.5 <SEP> 5.5 <SEP> 10.5 <SEP> 0.60 <SEP> 1.55
<tb> B2 <SEP> 9 <SEP> 12 <SEP> 3.5 <SEP> 10 <SEP> 0.40 <SEP> 1.35
<tb> C2 <SEP> 8.5 <SEP> 9 <SEP> 3 <SEP> 4 <SEP> 0.40 <SEP> 0.45
<tb> D2 <SEP> 8 <SEP> 8.5 <SEP> 2.5 <SEP> 3 <SEP> 0.35 <SEP> 0.40
<tb> d <SEP> = <SEP> start <SEP> of <SEP> test, <SEP> f <SEP> = <SEP> end <SEP> of <SEP> test.
<tb>

d = start of test, f = end of test.

TABLE 6
Hot engine idle noise emissions in dBA

<tb> Exterior <SEP> Interior
<tb> Fuel <SEP> d <SEP> f <SEP> d <SEP> f
<tb> A2 <SEP> 65.5 <SEP> 68 <SEP> 57 <SEP> 60.5
<tb> B2 <SEP> 63.5 <SEP> 66 <SEP> 55.5 <SEP> 58.3
<tb> C2 <SEP> 64.2 <SEP> 64.6 <SEP> 56.2 <SEP> 57
<tb> D2 <SEP> 63 <SEP> 63.4 <SEP> 54 <SEP> 54.7
<tb> d = start of test, f = end of test.

Example 14
Diesel fuels containing additive formulations consisting, on the one hand of isooctyl nitrate and, on the other hand, of the products prepared in Examples 1 and 3 to 8, 10 and 11. The results observed are similar to those reported in Examples 12 and 13.

Example 15
The experiment of Example 12 is repeated, substituting the isooctyl nitrate with the same quantity by weight of the nitrate corresponding to the formula
R - (- O-CH2-CH-) 2- O - NO2 in which R represents a mixture of alkyl radicals obtained from a cut of C -C monoalcohols of the "Alfol" type.

The test results are similar to those observed in Example 12.

Claims (10)

1. Formulation of additives for diesel fuels characterized in that it comprises from 5 to 95 by mass of a constituent (1) consisting of at least one terpolymer containing from 10 to 94-% by moles of units (A) derived from of at least one polymerizable ester of monocarboxylic acid chosen from acrylic esters of general formula

and vinyl esters of general formula

in which R1 is a hydrogen atom or a methyl radical and in which R- is a hydrogen atom or a methyl radical and R2 represents at least one alkyl radical of 1 to 30 carbon atoms; from 3 to 65 mol% of units (B) deriving from at least one ethylenically unsaturated dicarboxylic compound and corresponding to one of the general formulas

in which R3 and R4, identical or different, represent a hydrogen atom or a methyl radical, X and Y, identical or different, are chosen from the groups -OH, -OR5, -NH2-, and -NH, R5 representing a monovalent organic radical derived from a compound containing at least one hydroxyl function and / or at least one amine function; and from 3 to 40% by moles of units (C) corresponding to the formula

<tb> said terpolymer having a number average molecular weight of 500 to 250,000; and from 95 to 5% by mass of a component (2) consisting of at least one organic nitrate. <tb> and <SEP> deriving <SEP> from <SEP> diisobutylene <SEP> CH3 <tb> <SEP> H3C <SEP> - <SEP> C <SEP> - <SEP> CH3 <tb> <SEP> CH2 <tb> <SEP> + <SEP> CH <SEP> ~ <SEP> | <SEP> 4 2. Formulation according to claim 1, characterized in that the proportion of said component (1) is 10 to 90% by mass and the proportion of said component (2) is 90 to 10% by mass. 3. Formulation according to one of claims 1 and 2, characterized in that the constituent (1) comprises from 40 to 80% of units (A), from 10 to 40% of units (B) and from 10 to 30 X of patterns (C). 4. Formulation according to one of claims 1 to 3, characterized in that, in component (1) the units (A) derived from at least one polymerizable ester of monocarboxylic acid correspond to the formula

in which R2 contains from 4 to 22 carbon atoms, 5. Formulation according to one of claims 1 to 3, characterized in that, in component (1), the units (A) derived from a polymerizable ester of monocarboxylic acid correspond to the formula

wherein R2 contains 1 to 22-carhone atoms. 6. Formulation according to one of claims 1 to 5, characterized in that, in component (1), at least part of the units (B) bears ester, amide and imide groups resulting from the condensation on the X groups. , 2 dicarboxylic acids or anhydrides, of at least one compound containing at least one hydroxyl function and / or at least one amine function. 7. Formulation according to claim 6, characterized in that said compound containing at least one hydroxyl function and / or at least one amine function is chosen from 3-dimethylaminopropylamine, triethylenetetramine, tetraethylenepentamine, 1 'aminopyridine, diethylethanolamine, diethanolamine, cyano-l guanidine, trimethylolpropane, glycerol, pentaerythritol and linear aliphatic monoalcohols. 8. Formulation according to one of claims 1 to 7, characterized in that the component (2) consists of an organic aliphatic or cycloaliphatic nitrate containing from 1 to 12 carbon atoms optionally substituted by at least one group containing at least one atom. oxygen. 9. Diesel fuel composition, comprising a major proportion of at least one diesel fuel and a proportion of 0.1 to 25 kg / m3 of a formulation according to one of claims 1 to 8; 10. Diesel fuel composition according to claim 9, characterized in that it further comprises a minor proportion of a metal deactivator containing a salicylidene group.