CA2146573C - Oil middle distillate composition containing a paraffin sedimentation rate limiting agent - Google Patents

Abstract

A middle petroleum distillate composition containing a major proportion of middle petroleum distillate and a minor proportion of an additive in a sufficient amount to limit the settling speed of paraffins contained in said middle distillate. Said additive consists of a product resulting from a reaction between at least one aliphatic dicarboxylic compound and at least one primary amine functional compound of general formula (I), wherein R<1> is a monovalent saturated aliphatic radical, Z is selected from -NR'- groupings in which R' is a hydrogen atom or a monovalent saturated aliphatic radical, n is an integer between 2 and 4, and m is an integer between 1 and 4; said primary amine functional compound being used in a ratio of 0.3-0.8 mols per mol of said dicarboxylic compound.

Description

~ JVO 94/13758 PCT / FR93 / 01212 MEDIUM PETROLEUM DISTILLATE COMPOSITION COMPRISING A LIMITING AGENT
SPEED OF SEDIMENTATION OF PARAFFINS.
The invention relates to middle distillates of hydrocarbons (fuel oils, diesel), in which decantation of paraffins is slowed down by the addition of additives nitrogen. She also relates to a method for slowing settling or sedimentation paraffins a middle distillate of hydrocarbons by the addition of a minor proportion at least one nitrogen additive.
The petroleum distillates concerned by the invention consist of middle distillates (fuel oils, gas oils) containing paraffins whose distillation interval (ASTM D 86-67) is between 150 ° C and 450 ° C. Gas oils considered more especially have a distillation range from an initial temperature of between 160 ° C and 190 ° C to a final temperature of between 350 ° C and 390 ° C.
There exists on the market a large number of products recommended to improve the filterability limit temperature and the pour point of the slices rich oil companies paraffins, such as for example polymers based on long-chain olefins copolymers based on alpha-olefins, ethylene-vinyl acetate copolymers, the N-acylaminoethyl esters of polymers containing acids, or halocarbon compounds.
These products act on the kinetic phenomena of crystallization and change the size crystals, allowing the suspension to be used at a higher temperature low without clogging of pipes and filters.
There are also on the market additives that lower the cloud point cuts by changing the temperature at which the first crystals of paraffins.
The lowering of the cloud point of middle distillates (especially diesel) by a additive, is important for refiners because it allows modify the distillation scheme, to meet the specifications, which evolve currently in the sense of greater severity.

two By the way, when paraffin crystals whose formation is caused by the have appeared, their natural tendency is to come together by severity in the lower part. This phenomenon, generally known as sedimentation, causes clogging of the pipes and filters and is detrimental the good use of middle distillates, especially low-grade diesel temperature-The class of chemical compounds described in EP-B-71513 as additives to lower the cloud point of middle distillates hydrocarbons and having a significant effect on the filterability limit temperature and on the 1 o flow temperature are also described as having an action on speed sedimentation of paraffins formed by cooling gas oils and other middle distillates.
The additives considered in this application and defined below, are neighbors additives described in EP-B-71513 and belong to the same class of chemical compounds. Surprisingly, it has been discovered that in the class of chemical compounds generically described in the patent EP-B-71513, some of them, which have not been described in this document, have far superior properties with respect to their action on the sedimentation rate of paraffins and are so-called anti-additives sedimentation 2 o More effective under more severe test conditions.
Finally, the products recommended in the present invention for their properties anti-sedimentation mentioned above, also confer gas oils and other distillates mayens to which they are added, anti-aging properties corrosion on metal surfaces.
Note that have already been described in the prior art (US-A-2,638,450) as corrosion inhibitor additives in mineral oils, gasolines and other light petroleum products, N-alkylated polyalkylenepolyamine derivatives and of alkenylsuccinic acid anhydrides. These compounds are obtained in two steps

Alkylation of a polyalkylenepolyamine using a halogenide alkyl having from 4 to 31 carbon atoms. The alkylated polyalkylenepolyamine obtained from this way can have an extremely variable structure, the presence of derived from C-alkylation and N-alkylation derivatives being allowed.

2a 2) Reaction of alkylated polyalkylenepolyamine with anhydride of an acid alkenylsuccinic. The molar ratio of polyamine to anhydride depends on rate polyamine alkylation, i.e. the molar ratio polyamine / halide alkyl used in the alkylation phase; it can be lower or equal to 1.
Due to the prior alkylation of the polyamine which gives probably birth to C-alkylation derivatives and N-alkylation derivatives of various amino groups, these additives are different from the compounds whose use is claims in this application. In addition, this earlier document teaches the use of these anti-corrosion agent for petroleum derivatives of which it is not not said that they give rise to the phenomenon of crystallization of paraffins. This document does not besides, no reference to this particular problem.
In general, the middle petroleum distillate compositions according to the present invention may be defined as comprising a proportion most petroleum distillate and a minor proportion sufficient to limit the sedimentation rate of the paraffins it contains, of at least one additive consisting into a product of average molecular weight of about 300 to 10,000 resulting from the reaction of at least one aliphatic dicarboxylic compound selected from anhydrides maleic and alkyl maleic anhydrides, alkenyl succinic anhydrides with 10 to 32 carbon atoms in the radical alkenyl, dicarboxylic acids and diesters corresponding alkyls of 1 to 4 carbon atoms, and of at least one compound having a primary amine function corresponding to the general formula (I):
R1-Z (CH2) -NH H
not .
m where R ~ represents a monovalent saturated aliphatic radical having from 1 to 32 atoms of carbon, Z is selected from the groups -NR'- in which R 'represents a hydrogen atom or a monovalent saturated aliphatic radical having from 1 to 32 carbon of carbon, n is uri integer number from 2 to 4, m is an integer from 1 to 4 ; said compound with a primary amine function being used in a proportion of 0.3 to 0.8 mole per mole of said dicarboxylic compound and said reaction being carried out at a temperature of 120 to 200 ° C, and continued until the end of release of volatile products consisting of water and / or alcohol formed during the reaction. The more often the reaction is continued for a time sufficient to form the theoretical amount of volatile products consisting of water and / or alcohol, which are eliminated. In a preferred embodiment the radicals R1 and R 'are linear saturated aliphatic radicals.
The present invention also relates to a method for decreasing speed of sedimentation of paraffins contained in a mixture of hydrocarbons comprising the introduction into this mixture of hydrocarbons of a minor amount sufficient for reduce the sedimentation rate of paraffins, at least one additive consisting of a product of average molecular weight of about 300 to 10,000 resulting from fa reaction of at least one aliphatic dicarboxylic compound selected from anhydrides maleic and alkylmaleic anhydrides, the alkylesuccinic anhydrides having from 10 to carbon atoms in the alkenyl radical, dicarboxylic acids and diesters corresponding alkyls of 1 to 4 carbon atoms, and of at least one compound having a primary amine function corresponding to the general formula (I):
Rt-Z (CH, ~) -NH H
-not m ~~ .46 ~ ~

4 in which Z, R1, n and m have the definition given above, said compound function primary amine being used in a proportion of 0.3 to 0.8 moles per mole said dicarboxylic compound and said reaction being carried out at a temperature of 120 to 200 ° C, and continued until the end of product release volatile in water and / or alcohol formed during the reaction.
The compounds of formula (I) may consist of derived polyamines amine saturated aliphatic compounds having the formula Rt-Z ~ (CH2) -NH tH
,not which corresponds to the general formula (I) in which Z represents the group -NH-; m can have a value of 1 to 4 and n a value of 2 to 4, of preferably my a value of 2 to 4 and n is 3; Rt is preferably a radical saturated aliphatic monovalent linear having from 12 to 32 carbon atoms and more especially 16 at 24 carbon atoms.
As specific compounds, mention may be made of: N-dodecyl-1,3-diaminopropane, the N-tetradecyl-1,3-diaminopropane, N-hexadecyl-1,3-diaminopropane, N-octadecyl diamino-1,3 propane, N-eicosyl-1,3-diamine propane, the N-docosyl-1,3-diaminopropane, N-hexadecyldipropylene triamine, N-octadecyl dipropylene triamine, N-eicosyldipropylene triamine and N-docosyldipropylene triamine. Most advantageously, the N-docosyl-, N-eicosyl-, N-octadecyl, N-hexadecyl- or N-dodecyl-1,3-diaminopropane, and preferably dipropylene triamines such as N-hexadecyl or N-octadecyl dipropylene triamine.
The compounds of formula (I) may also consist of polyamines answering to the formula R
N ~ (CH ~) ~ -NH H
m R
which corresponds to the general formula (1) in which R1-Z
represents the group -NR2R3 where R2 and R3, which are identical or different, have the same definition as R1 and are each of preferably an alkyl radical having from 1 to 24 and preferably from 6 to 24 carbon atoms, R2 and R3 containing between them, preferably from 12 to 32 carbon atoms; n / A
a value of 2 to 4, preferably 3 and m a value of 1 to 4, preferably from 2 to 4.
Specific compounds that may be mentioned include N, N -diethyl-1,2-diaminoethane, the N, N-dsopropyl-1,2-diaminoethane, N, N-dibutyl-1,2-diaminoethane, N, N
diethyl-1,4-diamino-butane, N, N-dimethyl-1,3-diaminopropane, N, N-diethyl 1,3-diaminopropane, N, N-dioctyl-1,3-diaminopropane, N, N-didecyldiamino 1,3 propane, N, N-didodecyl-1,3-diaminopropane, N, N-ditetradecyl-diamino 1,3 propane, N, N-1,3-dihexadecyl-1,3-propane, N, N-dioctadecyldiamino 1,3 propane, and as preferred specific compounds N, N-didodécyldipropylène triamine, N, N-ditetradecyl-dipropylene triamine, N, N-dihexadécyldipropylène Triamine and N, N-dioctadecyl dipropylene triamine.
It must be understood that, without departing from the scope of the invention, it is possible to put in one or more compounds corresponding to formula (I).
The dicarboxylic compounds on which the condensation of a composed of formula (I) as described above, are more particularly chosen among maleic anhydride, alkylmaleic anhydrides, for example anhydride methylmaleic (or citraconic) or alkenyl-succinics, for example those obtained by the action of at least one olefin, linear preference, (for example having 10 to 32 carbon atoms) on anhydride 3o evil. More specifically, n-octadecenyl anhydride may be mentioned succinic acid or dodecenylsuccinic anhydride. It is possible, of course, to use mixtures of two (or more) of these compounds ;.
~ s Instead of the anhydrides mentioned above, it is possible to use the acids corresponding dicarboxylic acids, as well as the light alkyl diesters of these ci (such that, for example, methyl, ethyl, propyl and butyl esters).
The primary amine compounds of formula (I) are usually used to 0.3 to 0.8 mole, preferably 0.4 to 0.7 mole, per mole of compound dicarboxylic.
Condensation of compounds of formula (1) on dicarboxylic compounds (by dicarboxylic acids, esters, or preferably anhydrides) may be done without solvent, but preferably a hydrocarbon point solvent will be used boiling point between 70 ° C and 250 ° C, especially in one aromatic hydrocarbon or naphtheno-aromatic hydrocarbon, for example: toluene, xylenes, isopropylbenzene or even a petroleum cut having interval appropriate distillation.
To prepare the additive compositions considered in the invention, can in the practice in the following manner: in a reactor containing the compound dicarboxylic acid, and maintaining the temperature between 30 ° C and 80 ° C
° C, we introduce little to a little the compound of formula (I). The temperature is then raised to 120 ° C-200 ° C in eliminating volatile products formed (water or alcohols), either by training with a flow of inert gas, either by azeotropic distillation with the solvent chosen; the concentration in dry matter is for example 40 to 70%, most often neighbor 60%.
The reaction time, after addition of the reagents, is for example between 1 and 8 hours and preferably between 3 and 6 hours.
The additives considered in the invention are particularly interesting for slow down the decantation of paraffins in middle distillates of oil {especially diesel).
Although the mechanism of action of these additives on the sedimentation rate of the paraffin crystals in middle distillates has not yet been clearly elucidated, there is a marked slowdown in the decantation of paraffins in the ~ WO 94/13758 middle distillates treated with these additives, when added to concentrations for example from 20 to 2000 grams per tonne (g / t) of middle distillate.
The Preferred concentrations range from 100 to 2000 g / t.
Moreover, it is remarkable to note that the additives considered in the invention which have the property of inhibiting the sedimentation of n-paraffins in middle distillates at rest, also inhibit corrosion of metal surfaces in contact with these distillates.
In the concentration range of the additive, from 20 g to 2000 g / t, it is possible to observe a decrease in the proportion of sedimented paraffins until 100% under the conditions of the tests described in patent EP-B-71513 but as well under more severe temperature conditions of 5 to 10 ° C. In addition, an effect net corrosion is observed especially on ferrous metals.
To formulate the middle distillate compositions of the invention, it is possible to add the additives directly to the middle distillate by a simple operation of mixed.
However, it is often advantageous to introduce them in the form of "solutions "previously prepared in the solvents already mentioned above.
"mother solutions" may contain, for example, 20 to 60% by weight additives.
The compositions of middle petroleum distillates (for example gas oils) of the invention may also contain other additives, in particular other additives intended to improve cold behavior for example additives lowering the point flow and additives lowering the filterability limit temperature distillates means (eg gas oils).
The present invention also relates to the use of at least one compound of formula (I) R1-Z + (CH2) -Iv'H H
not m .T ~~ ~~ ~ 3 '~ E
r there in which Z, R1, n and m have the definition given above, in one proportion of 20 to 2,000 parts per million of the total weight of the composition, as that additive reducing the sedimentation rate of paraffins in a hydrocarbon composition consisting of a major proportion of an average hydrocarbon distillate containing paraffins. It also relates to the use of at least one compound of formula (I) above in a proportion of 20 to 2,000 parts per million of weight total composition, as an anticorrosive additive in a composition hydrocarbon product consisting of a major proportion of a middle distillate hydrocarbons containing paraffins.
In this context, it is advantageous to use at least one compound of formula (I) consisting of at least one polyamine having one of the following formulas R1 _NH-I (CH2) n-NH-1 m H

N ~ (CH2) n NH ~ H
R3 m in which R 1, R 2, R 3, n and m have the definition given above.
The following examples illustrate the invention and should in no way to be considered as limiting.
~~ example 1 (com, are atif) 20 g of a reactor with good stirring are introduced into 2.700 g of commercial polyamine (containing a mixture of about 27% palmityl 1,3 propane diamine and about 70% stearyl 1,3 propane diamine, said mixture having an equivalent of 370 g for a primary amine group) and 2,700 g of xylene, one dissolve the amine at 50 ° C and then cool to 30 ° C, add a solution of 699 g of maleic anhydride dissolved in 1.050 g of xylene while maintaining the temperature inside at 40 ° C; the addition lasts an hour, then heated for 3 hours at the the reflux temperature of the xylene, the internal temperature of the reactor is 144 ° C, 157 g of water corresponding to 128 g of water of water are distilled off.
reaction and 29 g ~ O 94 / I3758 PCT / FR93 / 01212 water contained in the starting amine; at the end of the reaction we distil 500 g of xylene to obtain a solution containing 50% by weight of the additive I in xylene.
Additive I was analyzed after evaporation of the solvent. Its molecular mass average in number, measured by tonometry is 1800. The infra-red spectrum in layer slim shows the existence of imide bands at 1700 and 1780 cm- ~, secondary amide at 1635 and 1560 cm 1 and secondary amine at 3300 cm This additive is that described in Example 1 of EP-B-71513.
~ xem ~ I ~ e 2 Example 1 is repeated using N-stearylpropylenepropylamine as amine.
triamine in a proportion of 0.75 mole of amine per mole of anhydride. We maintain the reactor to the reflux temperature of the xylene for 3 hours 30 at the end of which it no longer water removal. We adjust the amount of xylene to obtain a solution at 50% in weight of additive II in xylene.
Additive II was analyzed after evaporation of the solvent. Its molecular mass average in number measured by tonometry is 1600. The infra-red spectrum in layer thin shows the existence of imide strips at 1700 and 1780 cm-1, secondary amide at 1635 and 1560 cm-1 and secondary amine at 3300 cm-1.
exam Example 2 is repeated using N-stearylpropylenepropane as amine.
triamine and as anhydride, N-octadecenyl succinic anhydride in a proportion of 0.70 mole of amine per mole of anhydride. The reactor is kept at the temperature reflux xylene for 4 hours at the end of which there is no more elimination of water. We adjust the amount of xylene to obtain a 50% solution by weight of additive III
in xylene.
Additive I11 was analyzed after evaporation of the solvent. Its molecular mass average in number measured by tonometry is 1700. The infra-red spectrum layer thin shows the existence of imide strips at 1700 and ', ° 10 1780 cm-1, secondary amide at 1365 and 1560 cm-1 and secondary amine at 3300 cm-1.
Example 4 Example 2 is repeated using N-stearylpropylenepropane as amine.
triamine and anhydride is N-octadecenyl succinic anhydride in a proportion of 0.5 mole of amine per mole of anhydride. The reactor is maintained at the temperature of reflux of xylene for 3 hours after which no water is removed.
We adjust the amount of xylene to obtain a 50% solution by weight of the additive IV in the xylene.
Additive IV was analyzed after evaporation of the solvent. Its molecular mass average in number measured by tonometry is 1650. The infra-red spectrum layered thin shows the existence of imide strips at 1700 and 1780 cm-1, secondary amide at 1365 and 1560 cm-1 and secondary amine at 3300 cm-1.
Exem Ip e 5 The inhibitory action of additive I and additives II and IV is tested according to the invention on the sedimentation of n-paraffins crystallizing in two winter gas oils commercial, whose characteristics are shown in Table I below ~ O 94/13758 PCTIFR93101212 TABLE I
Gaaole Diesel commercial commercial N

Densit 15 0.844 0.843 VS

Distillation Initial Point 172 166 % 200 190 % 213 199 20% 231 21 4 30% 246,228 40% 260,242 50% 273 257 60% 286,269 70% 300 2g5 80% 314,305 90% 332,336 95% 343,359 Final Point 359 373 N-paraffins 1 0.1 1 0, 0 Cloud point- 6 _ 6 Pour point- 2 7 - 3 0

These commercial gas oils contain 500 ppm by weight of a point ethylene-vinyl acetate (EVA) type flow type.
Two 250 cm3 test pieces are filled with diesel fuel No. 1. In the first test tube, no additive is introduced. In the second test tube, introduced 0.1 10% by weight of one of the additives.

WO 94/13758 ~ ~ PCT / FR93 / 01212 The two test tubes are sealed and then left to rest.
bedroom cold at -15 ° C for 24 hours. After 24 hours, the degree of sedimentation of precipitated paraffins is expressed by the v volumes of different phases sedimented quantity, slightly cloudy phase, cloudy phase, clear phase or limpid) in the test tube.
The following results are shown in Tables II, IV and VI below.
after.
The same test is carried out with the No. 2 diesel at -20 ° C for 24 hours.
H. The results are shown in Tables III, V and VII below.
The quality of the upper phase is decisive for the anti-sedimentation of the product: when the upper phase is turbid, a large proportion of paraffins remained in suspension. When this phase is clear, the quasi all paraffins sedimented. With a slightly cloudy upper phase, effectiveness anti-sedimentation is intermediate.
If we now consider the amount of sedimented paraffins: the higher the phase is dewaxed, the denser the sedimented phase, which makes the pumpability of diesel difficult. We can not compare the quantities of paraffins sedimented only if they are of equivalent density, that is to say if the phases are of the same nature.
Tables II and III relate to the results obtained with additive 1. The tables IV and V relate to the results obtained with additive II Tables VI and VII
relate to results obtained with additives III and IV.
TABLE II
Test tube N 1 Test tube N 2 Commercial diesel N 1 Commercial diesel N 1 + additive such as I

50 ml sdiment 100 ml sdiment + +

200 ml clear 150 ml slightly cloudy ~ O 94/13758 PCT / FR93 / 01212 TABLE III
Test tube N 1 Test tube N 2 Commercial diesel N 2 Commercial diesel N 2 + additive such as I

60 ml sediment 70 ml sdiment + +

190 ml clear 180 ml clear It is found that the additive I exemplified in EP-B-71513 for its effectiveness anti-Sedimentation at -10 ° C is less effective at -15 ° C and not effective at -20 ° C.
TABLE IV
Test tube N 1 Test tube N 2 Commercial diesel N 1 Commercial diesel N 1 + additive such as II

50 ml sdiment 55 ml sdiment + +

200 ml clear 195 ml slightly cloudy TABLE V
Test tube N 1 Test tube N 2 Commercial diesel N 2 Commercial diesel N 2 + additive such as II

60 ml sdiment 80 ml sdiment + +

190 ml clear 170 ml slightly cloudy The anti-sedimentation efficiency of additive II is greater than that of additive I, especially at -20 ° C.

WO 94/13758 ~ ~ ~ PCT / FR93 / 01212 14.
TABLE VI
Test tube N Test tube N 2 Test tube N 3 N 1 such gas oil N 1 gasoline + additiveGazole N 1 + additive III IV

50 ml sdiment 40 ml sdiment 2 ml sdiment + + +

200 ml clear 210 ml disorder 248 ml disorder TABLE VII
Test tube N Test tube N 2 Test tube N 3 N 2 gas oil N 2 gas oil + additiveGazole N 2 + additive III IV

60 ml sdiment 110 ml ssiment 10 ml sdiment + + +

190 ml clear 140 ml disorder 240 ml disorder A better dispersion of the paraffins is obtained with the additive III by report to additive II, but the ratio of reagents is an important factor for anti-efficiency sedimentation of additives: additive IV manages to ensure the best homogeneity diesel in cold storage.
Example Ip e 6 The anticorrosion effect of the additives I to IV described above is tested.
The additive is used in both gasplanes # 7 and # 2 already previously described in concentration of 0.01% by weight.
The corrosion test consists of studying corrosion by seawater synthetic, cylindrical specimens of steel or polished iron according to ASTM D 665 modified in the following way: the temperature is 32.2 ° C and the duration of 20 hours.

aW0 94/13758 PCTlFR93 / 01212 The two gas oils n ° 1 and n ° 2 not additive give test pieces rusted to 100 of their surface and the two gas oils containing 0.01% by weight of one of the additives described above give intact test pieces at 0% rust.
~, it '~ t, zy' ~ 'r ~;': ~: ~. ~ fT's,. ~ r ~ ~ 'C ~

Claims (18)

16 1. Petroleum middle distillate composition comprising a major proportion of petroleum middle distillate containing paraffins and whose distillation interval (standard ASTM D 86-67) is between 150 and 450°C and a proportion minor addition of at least one additive consisting of a product of average molecular mass of about 300 to 10,000 resulting of the reaction of at least one dicarboxylic compound aliphatic (a) selected from maleic anhydrides and alkylmaleic, alkenylsuccinic anhydrides having 10 to 32 carbon atoms in the 1st alkenyl radical, the dicarboxylic acids and diesters of alkyls from 1 to 4 corresponding carbon atoms, and of at least one compound with a primary amine function (b) corresponding to the formula general (I):
where R1 represents a monovalent saturated aliphatic radical of 1 to 32 carbon atoms carbon, Z is chosen from the amino groups -NR'- in which R' represents a hydrogen atom or a monovalent saturated aliphatic radical having 1 to 32 carbon atoms, n is an integer from 2 to 4, m is a integer from 1 to 4; characterized in that, for said additive presents a sufficient effectiveness in controlling the sedimentation of paraffins, said primary amine compound (b) is used in a proportion of 0.3 to 0.8 mole by mole of said dicarboxylic compound (a); and said reaction is performed at a temperature of 120 to 200°C, and continued until the end of the clearance of volatile products consisting of water and/or alcohol formed during the reaction. 2. composition according to claim 1 characterized in that the additive used results from the reaction of 0.4 to 0.7 mole of compound (b) per mole of compound (has). 3. Composition according to any one of claims 1 and 2, characterized in that compound (b) meets the formula (1) in which the radical R1 and, where appropriate, the radical R' are saturated aliphatic radicals linear. 4. Composition according to any one of claims 1 to 3, characterized in that the compound containing an amine function primary (b) consists of at least one polyamine of formula which corresponds to the general formula (I) in which Z represents the -NH- group, m is 1 to 4, n is 2 to 4, and R1 is a linear monovalent saturated aliphatic radical having from 12 to 32 carbon atoms carbon. 5. Composition according to claim 4, characterized in that that the primary amine functional compound (b) is chosen from N-dodecyl diamino-1,3 propane, N-tetradecyl 1,3-diaminopropane, N-hexadecyl 1,3-diaminopropane, N-octadecyl diamino-1,3 propane, N-eicosyl diamino-1,3 propane, N-docosyl diamino-1,3 propane, N-hexadecyldipropylene triamine, N-octadecyl dipropylene triamine, N-eicosyldipropylene triamine and N-docosyldipropylene triamine. 6. Composition according to claim 5, characterized in that that the primary amine functional compound (b) is chosen from N-docosyl-, N-eicosyl-, N-octadecyl, N-hexadecyl-or N-dodecyl-diamino 1,3 propane. 7. Composition according to claim 5, characterized in that that the primary amine functional compound (b) is chosen among the dipropylene triamines. 8. Composition according to claim 7, characterized in that that the dipropylene triamines are chosen from N-hexadecyl- and N-octadecyl-dipropylene-triamine. 9. Composition according to any one of claims 1 to 3, characterized in that the compound containing an amine function primary (b) consists of at least one polyamine of formula:
which corresponds to the general formula (1) in which R1-Z
represents the group -NR2R3 where R2 and R3, identical or different, are each an alkyl radical having from 1 to 24 carbon atoms, n has a value of 2 to 4 carbon atoms carbon and m has a value of 1 to 4 carbon atoms. 10. Composition according to claim 9, characterized in that the primary amine functional compound (b) is chosen from N,N-diethyl-diamino-1,2 ethane, N,N-1,2-diisopropyldiaminoethane, N,N-dibutyl-1,2-diaminoethane ethane, N,N-diethyl-1,4-diamino-butane, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, N,N-dioctyl-diamino-1,3 propane, N,N-didecyl-1,3-diamino propane, N,N-didodecyl-1,3-diamino propane, N,N-ditettradecyl-diamino-1,3 propane, N,N-dihexadecyldi-amino-1,3 propane and N,N-dioctadecyldiamino-1,3 propane. 11. Composition according to claim 9, characterized in that the primary amine functional compound (b) is chosen from N,N-didodecyldipropylene triamine, N,N-ditetra-decyldipropylene triamine, N,N-dihexadecyldipropylene triamine and N,N-dioctadecyldipropylene triamine. 12. Composition according to any one of the claims 1 to 11, characterized in that the dicarboxylic compound (a) is selected from the group formed by the anhydride maleic anhydride, methyl maleic anhydride, n-octadecenyl succinic and dodecenyl succinic anhydride. 13. Composition according to any one of the claims 1 to 12, characterized in that the reaction is carried out at in a hydrocarbon solvent with a boiling point between 70° and 250°C and includes the mixture "at a temperature of 30 to 80°C, of said dicarboxylic compound (a) with said compound (b) of formula (1) and heating the resulting mixture at a temperature of 120 to 200°C, for a duration of 1 to 8 hours. 14. Composition according to any one of the claims 1 to 13, characterized in that the middle distillate is a gas oil cut having a distillation range of from an initial temperature of 160 to 190°C to a temperature final 350 to 390°C. 15. Composition according to any one of the claims 1 to 14, characterized in that the proportion of said additive is 20 to 2000 grams per ton of middle distillate. 16. Method for controlling the sedimentation of paraffins in a petroleum middle distillate containing paraffins and whose distillation range (ASTM D86-67 standard) is between 150 and 450°C, characterized in that it comprises introducing into said middle distillate a proportion effective minor of at least one additive consisting of a product with an average molecular mass of approximately 300 at 10°000 resulting from the reaction of at least one compound aliphatic dicarboxylic acid (a) selected from anhydrides maleic and alkylmaleic anhydrides alkenylsuccinic compounds having 10 to 32 carbon atoms in the alkenyl radical, the dicarboxylic acids and the alkyl diesters of 1 to 4 carbon atoms corresponding, and of at least one compound containing an amine function primary (b) corresponding to the general formula (I):
where R1 represents a monovalent saturated aliphatic radical of 1 to 32 carbon atoms carbon, Z is chosen from the amino groups -NR'- in which R' represents a hydrogen atom or a monovalent saturated aliphatic radical having 1 to 32 carbon atoms, n is an integer from 2 to 4, m is a integer from 1 to 4; said primary amine compound (b) being used in a proportion of 0.3 to 0.8 mole per mole of said compound dicarboxylic (a); and said reaction being carried out at a temperature of 120 to 200°C, and being continued until the end of the release of the products volatile consisting of water and/or alcohol formed during the reaction. 17. Method according to claim 16, characterized in that that the additive used results from the reaction of 0.4 to 0.7 mole of compound (b) per mole of compound (a). 18. Method according to any one of claims 16 and 17, characterized in that the compound (b) corresponds to the formula (I) in which the radical R1 and, where appropriate, the radical R' are saturated aliphatic radicals linear.