EP0213027A1 - Dispersant additive compositions for lubricating oils, and their preparation - Google Patents

Abstract

Dispersing additive compositions for lubricating oils having improved efficacy are described. Such compositions can consist of (1) products obtained by reaction of alkenyl succinimides with aromatic dianhydrides, or (2) products obtained by reaction of alkenyl succinimides with an anhydride or a dianhydride of aliphatic mono- or polycarboxylic acid, alicyclic or aromatic of low molar mass, then reaction of the product obtained with at least one organic compound with several hydroxyl and / or amine functions. These dispersing additive compositions can be added to lubricating oils, for example in an amount of 0.1 to 20% by weight.

Description

Disclosed are dispersing compositions for lubricating oils with improved efficacy. More particularly, the invention relates to new dispersing compositions, soluble in lubricating oils, obtained (1) either by the reaction of polyalkenyl succinimides with certain dianhydrides, (2) or by the reaction of polyamine alkenyl succinimides with an anhydride or a low molecular weight aliphatic, alicyclic or aromatic mono- or polycarboxylic acid dianhydride, then reaction of the product obtained with at least one organic compound having several hydroxyl and / or amine functions.

One of the main problems currently encountered in engine lubricants is due to the inevitable presence in the lubricant of foreign particles in suspension, such as carbonaceous materials and sludges from soot, fuel alteration products and lubricant. , and water.

However, the accumulation of these suspended solids poses a serious problem for the efficiency of the lubricant in the engine and it is important to prevent agglomeration and the deposition of these undesirable materials in the form of varnish, hard carbonaceous materials and sludges in the different parts of the engine. For several years, attempts have been made to overcome these difficulties by the use of organometallic additives, such as for example sulfonates, phenates or salicylates of alkaline earth metals, or of organic additives, such as for example polymethacrylates grafted or copolymerized with nitrogenous monomers, or alkenyl succinimides of polyethylene polyamines, or alkenyl succinates of polyols.

However, the use of organometallic additives is limited by the risks of various deposits of metal oxides on the spark plug electrodes in spark-ignition engines; these deposits can cause pre-ignition which is harmful to the engines. Known ashless organic additives have the drawback of limited effectiveness at high temperature and also in certain cases in the presence of traces of water.

• 1) on fait réagir un anhydride polyalkénylsuccinique (par exemple polyisobuténylsuccinique dont la chaîne polyisobutényle présente une masse moléculaire moyenne en nombre de 900 à 2000) avec une alkylène polyamine ; puis
• 2) on fait réagir le produit obtenu à l'étape (1) avec un anhydride d'acide dicarboxylique tel que l'anhydride maléique, l'anhydride succinique et les anhydrides alkyl- et alkényl-succiniques ayant de 1 à 18 atomes de carbone dans la chaîne alkyle ou alkényle.

European patent application EP-A-72,645 describes dispersing additives for lubricating oils prepared by a process in which

• 1) reacting a polyalkenylsuccinic anhydride (for example polyisobutenylsuccinic whose polyisobutenyl chain has a number average molecular weight of 900 to 2000) with an alkylene polyamine; then
• 2) the product obtained in step (1) is reacted with a dicarboxylic acid anhydride such as maleic anhydride, succinic anhydride and the alkyl- and alkenyl-succinic anhydrides having from 1 to 18 carbon atoms in the alkyl or alkenyl chain.

The object of the invention is to provide new additive compositions for lubricating oils having improved properties, in particular better dispersing efficiency and increased thermal stability.

In general, the additive compositions of the invention can be defined either as the products (1) resulting from the reaction of at least one polyamine alkenyl succinimide with at least one low mass aromatic tetracarboxylic acid dianhydride. molecular, either as the products (2) resulting from the reaction of at least one polyamine alkenyl succinimide with at least one anhydride or a dianhydride of mono- or polycarboxylic acid, aliphatic, alicyclic or aromatic of low molecular weight, followed by the reaction of the product obtained with at least one organic compound with several hydroxyl and / or amine functions as defined in the description below.

More particularly, the alkenylsuccinimides of polyamines which can be used to prepare the additives of the invention are obtained by reaction of various polyamines with an alkenylsuccinic anhydride in which the alkenyl group is derived from a polymer of a 2> monoolefin containing from 2 to 5 carbon atoms (and more particularly of polyisobutene), in which the alkenyl group (for example polyisobutenyl) has a number-average molecular mass ( Mn) from 500 to 5000, preferably from 800 to 1500.

dans laquelle m est un entier de 0 à 10. Ces polyamines bi-primaires peuvent être par exemple l'éthylènediamine, ou des polyéthylènepolyamines telles que la diéthylènetriamine, la tétraéthylènepentamine, la pentaéthylènehexamine ou encore des mélanges de ces polyamines commercialement disponibles.The polyamines which are suitable for the preparation of the alkenyl succinimides considered in the invention correspond more particularly to the general formula:

in which m is an integer from 0 to 10. These bi-primary polyamines can be for example ethylenediamine, or polyethylene polyamines such as diethylenetriamine, tetraethylenepentamine, pentaethylenehexamine or mixtures of these commercially available polyamines.

The alkenyl succinic anhydride and the polyamine (as defined above) are reacted in a known manner, for example using a proportion of alkenyl succinic anhydride ranging from approximately 1 to 2 moles per mole of bi-primary polyamine.

The preparation of the additive compositions of the invention consisting of the products (1) or (2) comprises in all cases a step (a) in which at least one alkenyl succinimide as defined above is reacted with at least one anhydride or dianhydride of mono- or polycarboxylic acid, aliphatic, alicyclic or aromatic, of low molecular weight, for example of at most about 250. As examples of anhydrides and dianhydrides which can be used, in the case of products (2), there may be mentioned anhydrides of monocarboxylic acids, such as acetic and butyric anhydrides, and anhydrides of polycarboxylic acids, such as maleic and succinic anhydrides, or pyromellitic dianhydride. In the case of products

(1), essentially pyromellitic dianhydride is used.

The reaction used in this step (a) is carried out by mixing the reagents defined above in proportions generally corresponding to an alkenylsuccinimide / anhydride molar ratio of 0.25 / 1 to 20/1 and preferably 0.5 / 1 to 10/1. We operate at a temperature which can range from 20 to 200 ° C. One can for example start the reaction at relatively low temperature (for example 20 to 50 ° C) and finish it at higher temperature, for example at about 130-180 ° C.

The reaction is most often carried out using as solvent a mineral oil such as 100 Neutral oil, for example in a proportion such that the final product contains from 50 to 70% by weight of active material. In certain cases, a certain amount of an aromatic solvent, such as for example xylene or toluene, is also used. The operation is then carried out at reflux of the aromatic solvent. This solvent can be removed at the end of the reaction by heating the reaction mixture, for example under reduced pressure.

The reaction is complex, but one can think that there is a superposition of several reactions between the anhydride and the primary and secondary amine groups of the alkenyl succinimide. This results, according to the operating conditions and in particular according to the nature of the anhydride and according to the anhydride / alkenylsuccinimide molar ratio, an increase in the molecular mass, a decrease in the TBN (total base index) and an increase in the TAN ( total acid number).

• - les polyols aliphatiques, renfermant de préférence de 3 à 6 groupements hydroxyles, tels que par exemple le triméthylolpropane, le pentaérythritol ou le dipentaérythritol;
• - les aminoalcools aliphatiques, renfermant de préférence une fonction amine primaire et de 1 à 3 fonctions hydroxyles, tels que par exemple l'amino-2 méthyl-2 propanol ou le tris-hydroxymétyl amino-méthane ;
• - les polyamines de formule générale H₂N CH₂ CH₂-(NH CH₂ CH₂)_m NH₂ telles que définies plus haut ; et
• - les esters à fonctions hydroxyles libres formés entre un anhydride alkénylsuccinique et un polyol, tels que par exemple les polyisobuténylsuccinates de triméthylolpropane, de pentaérythritol, ou de dipentaérythritol.

For the preparation of the products (2), the products obtained in step (a) are then reacted, in a second step (b), with at least one organic compound with several hydroxyl and / or amine functions, more particularly chosen from the following families:

• - Aliphatic polyols, preferably containing 3 to 6 hydroxyl groups, such as for example trimethylolpropane, pentaerythritol or dipentaerythritol;
• - Aliphatic amino alcohols, preferably containing a primary amine function and from 1 to 3 hydroxyl functions, such as for example 2-amino-2-methylpropanol or tris-hydroxymetyl amino-methane;
• - the polyamines of general formula H ₂ N CH ₂ CH ₂ - (NH CH ₂ CH ₂ ) _m NH ₂ as defined above; and
• - Esters with free hydroxyl functions formed between an alkenyl succinic anhydride and a polyol, such as for example polyisobutenyl succinates of trimethylolpropane, pentaerythritol, or dipentaerythritol.

The reaction used in the second step (b) is carried out by mixing the reagents defined above in proportions generally corresponding to a molar support of organic compound / anhydride of 0.25 / 1 to 4/1 and preferably 0.5 at 2/1. The operation is carried out at a temperature which can range from 100 to 200 ° C., preferably close to 150 ° C. The reaction is most often carried out in the same solvent as in step (a), in general a mineral oil, for example a 100 Neutral oil.

Generally, the additive compositions of the invention can be used in lubricants alone or in combination with other conventional additives. As dispersing additives in oils, they can be used in proportions ranging from 0.1 to 20% by weight of the lubricant, depending on the use for which the lubricant is intended and according to the presence or absence of other specially dispersing additives. and / or detergents. Ordinarily, their proportion may vary from 1 to 10% by weight of the lubricant. The compositions of the invention may be incorporated into various oils of mineral, synthetic or mixed bases, used for various purposes, such as lubricants for internal combustion engines with positive ignition or with compression ignition, (such as for example (cars or trucks, two-stroke engines, piston aircraft engines, marine engines or even railway diesel). In addition, automatic transmission, gear, metalworking, hydraulic and grease fluids can also benefit from the incorporation of the additives of the invention.

Normally, the compositions of the invention are used in admixture with other conventional additives. These include phosphorus or sulfur products improving the extreme pressure properties, organometallic detergents, such as phenate sulfides, sulfonates and salicylates of alkaline earth metals, ashless dispersants, thickening polymers, as well as anti-freezing agents, oxidation inhibitors, anti-corrosive agents, anti-rust and anti-foam, etc.

The following examples illustrate the invention but should in no way be considered as limiting. Examples 1, 3, 5, 7 and 9 are given for comparison.

In these examples, the mixtures of polyisobutenyl succinimides A, B and C are derived from polyisobutenyl succinic anhydride whose polyisobutenyl group has a number average molecular weight of approximately 920.

EXAMPLE 1 (comparative)

A 102 g of a mixture A containing 39 g of 100 Neutral oil and 63 g of a polyisobutenyl succinimide obtained by reaction of polyisobutenyl succinic anhydride and a commercial mixture of tetraethylene pentamine (TEPA) (in an anhydride / TEPA molar ratio of 1.5), 2.2 g (2.2 10 ^-2 mole) of maleic anhydride and 65 g of xylene are added. The reaction mixture is stirred for 4 hours at room temperature, then the xylene is removed by distillation under reduced pressure.

The reaction mixture is added in an amount of 3% by weight of active materials to a mineral oil formulated but not containing an ashless dispersant additive. The dispersing effectiveness of the composition of the invention is evaluated by the spot test on filter paper, in the presence of carbonaceous material obtained from a used diesel engine oil. The ratio between the diameters of the black spot and of the oil halo is determined after 48 hours, the mixture having undergone various treatments before being deposited on the filter paper. The conditions of the spot test and the results obtained are collated in Table I. In this table also appear the results obtained under the same conditions, with the oil formulated in the absence of dispersant additive without ash (mixture 0) and with the mixture A defined above.

A product prepared under the conditions of Example 1 is included as an ashless dispersant at a concentration of 3% by weight of active materials in a lubricating oil formulation at SF / CD level and subjected to an engine test of the VD sequence type. to assess protection against sludge, varnish and wear. This test, carried out according to standard ASTM 315 - Part III, is carried out with a FORD gasoline engine, 4 cylinders.

The results of this engine test (ratings: average piston varnish, average engine varnish and average sludge) are collated in Table II (1).

Furthermore, a product prepared under the conditions of Example 1 is included as an ashless dispersant at a concentration of 3% weight of active ingredients in a SAE 30 monograde lubricating oil formulation and subjected to an MWM engine test (B). The results of this engine test are collated in Table II (2).

EXAMPLE 2

To 102 g of the mixture A defined in Example 1, 2.2 g (2.2 10-2 mole) of maleic anhydride and 64 g of xylene are added. The reaction mixture is stirred for 3 hours at 30 ° C. To the reaction mixture thus obtained, 2.78 g (2.3 ^× 10 ^-2 mole) of tris-hydroxymethylaminomethane and 0.11 g of zinc acetate are added as catalyst. The mixture thus obtained is stirred at 30 ° C for 30 minutes, then heated to reflux of xylene for 6 hours. The reaction mixture is freed from xylene by distillation under reduced pressure and then added with 19.2 g of 100 Neutral oil and finally filtered. The dispersing efficacy, evaluated in the same way as in Example 1, is illustrated by the results collated in Table I.

A product prepared under the conditions of Example 2 is included as an ashless dispersant at a concentration of 3% by weight of active materials in the formulation of lubricating oil at SF / CD level of Example 1 and subjected to a test. VD sequence type engine. The results of this engine test, appearing in table II (1), illustrate the improvement brought by the additive of example 2 compared to the product of comparative example 1. In table II (2), also appears the result of the MWM engine test (B) carried out under the conditions described in example 1, but using as additive dispersant without ash the additive of example 2. The result also illustrates the improvement brought by replacement of the additive of Comparative Example 1 by that of Example 2.

EXAMPLE 3 (comparative)

To 85 g of the mixture A defined in Example 1, 3.7 g (3.8 10 ^-2 mole) of maleic anhydride and 70 g of xylene are added. The reaction mixture is heated for 5 hours at reflux, then the xylene is removed by distillation under reduced pressure. The results of the dispersing efficiency tests of this mixture are shown in Table I. Table II collates the results of the engine tests with the product of this example.

EXAMPLE 4

To 85 g of the mixture A defined in Example 1, 3.7 g (3.8 10 ^-2 mole) of maleic anhydride and 70 g of xylene are added. The reaction mixture is heated for 5 hours at reflux, then the xylene is removed by distillation under reduced pressure. 1.54 g (approximately 1.15 × 10 ^-2 mole) of trimethylolpropane are added to the reaction mixture. The mixture is then brought to 150 ° C for 6 hours.

The excellent dispersing efficiency of the product obtained is illustrated by the results appearing in Table I. In addition, the results of the VD and MWM (B) sequence engine tests reported in Table II show the improvement brought by the replacement of the product of Example 3 with that of Example 4.

EXAMPLE 5 (comparative)

A 95g of a mixture B containing 37g of 100 Neutral oil and 58g of a polyisobutenyl succinimide obtained by reaction of polyisobutenyl succinic anhydride and a commercial mixture of tetraethylenpentamine (anhydride / TEPA molar ratio = 2), we add 1.05 g (about 10 ^-2 mole) of maleic anhydride and 70 g of xylene. The reaction mixture is heated for 2.5 hours at reflux and the xylene is then removed by distillation under reduced pressure. The dispersing effectiveness of the product of this example, as well as that of mixture B, are illustrated by the results appearing in Table I.

EXAMPLE 6

Example 5 is repeated, adding to the reaction mixture (before removing the xylene) 2.1 g of trimethylolpropane (ie 1.57 × 10 ^-2 mole). Then heated at reflux for 5 hours. Then the xylene is removed by distillation under reduced pressure.

An additive composition is obtained which has a dispersing efficiency clearly greater than that of the product of Example 5, as shown by the results collated in the table!

EXAMPLE 7 (comparative)

To 2438g of a mixture C containing 731g of 100 Neutral oil and 1707g of a polyisobutenyl succinimide obtained by reaction of polyisobutenyl succinic anhydride and of a commercial mixture of tetraethylene pentamine (molar ratio anhydride / TEPA = 1.8), 105 is added. , 2g of maleic anhydride (about 1.07 mole). The reaction mixture is heated for 3 hours at 80 ° C.

The dispersing effectiveness of the product of this example, as well as that of the initial mixture C, are illustrated by the results appearing in Table I.

EXAMPLE 8

Example 7 is repeated, adding, after reaction of the maleic anhydride, 44.3 g of pentaerythritol (or about 32.6 10 ^-2 mole).

The reaction mixture thus obtained is heated for 5 hours at 190 ° C.

The product obtained has a nitrogen content of 1.74% by weight.

Its excellent dispersing efficiency is shown by the results collated in Table I. It is clearly superior to that of the product of Example 7.

EXAMPLE 9 (comparative)

To 2423 g of the mixture C defined in Example 7, 51.2 g of maleic anhydride (ie 52.2 10 ^-2 mole) are added. The reaction mixture is brought to 60 ° C for 3 hours.

The dispersing effectiveness of the product of this example is illustrated by the results appearing in Table I.

EXAMPLE 10

Example 9 is repeated, adding, after reaction of the maleic anhydride, 64.6 g of tris-hydroxymethylaminomethane (ie 53.4 10 ^-2 mole) and 2.66 g of zinc acetate. Then heated to 165 ° C for 6 hours.

The product obtained has an excellent dispersing efficiency, clearly superior to that of the product of Example 9, as shown by the results collated in Table I.

EXAMPLE 11

Example 9 is repeated again. After reaction of the maleic anhydride, 1153 g of reaction mixture are taken, to which 796 g of a solution containing 318 g of a polyisobutenyl trimethylolpropane succisate (itself formed by anhydride reaction) are added. polyisobutenyl succinic acid and trimethylolpropane in an anhydride / trimethylolpropane molar ratio of 0.5). The reaction mixture is then heated at 160 ° C for 7 hours.

The excellent dispersing efficiency of the product obtained is illustrated by the results appearing in Table I. It is to be compared to that of the product of Example 9.

EXAMPLE 12

Example 9 is repeated again, adding after reaction of maleic anhydride, 70 g of a commercial mixture of tetraethylene pentamine. The reaction mixture is heated at 160 ° C for 3 hours. The excellent dispersing efficiency of the product obtained, clearly superior to that of the product of Example 9, is illustrated in Table I.

Claims (10)

1. Composition of additive with improved dispersing effect in lubricating oils, characterized in that it essentially consists (1) in the product resulting from reaction (a) of at least one alkenyl succinimide with at least one dianhydride of aromatic polycarboxylic acid; or (2) in the product resulting from the reaction of at least one alkenyl succinimide with at least one anhydride or a dianhydride of mono- or polycarboxylic acid, aliphatic, alicyclic or aromatic of low molecular mass, followed by reaction (b) of product obtained, with at least one organic compound having several functions chosen from hydroxyl and amine functions. 2. Composition according to claim 1, characterized in that said alkenyl succinimide involved in reaction (a) results from the prior reaction of at least one alkenyl succinic anhydride whose alkenyl group has a number average molecular weight of 500 to 5000 with at least one bi-primary polyamine of general formula

in which m is an integer from 0 to 10, in proportions ranging from approximately 1 to 2 moles of alkenylsuccinic anhydride per mole of bi-primary polyamine. 3. Composition according to claim 1 or 2, characterized in that it essentially consists of a product (1) resulting from the reaction (a) of at least one alkenylsuccinimide with pyromellitic dianhydride. 4. Composition according to claim 1 or 2, characterized in that it essentially consists of a product (2) resulting from the reaction (a) of at least one alkenylsuccinimide with at least one anhydride or dianhydride having a molecular weight of at most 250, followed by reaction (b) of the product obtained, with at least one organic compound chosen from aliphatic polyols, aliphatic amino alcohols, polyethylene polyamines and esters of alkenyl succinic acids and polyols. 5. Composition according to claim 4, characterized in that, in reaction (a), said anhydride or dianhydride is acetic anhydride, butyric anhydride, maleic anhydride, succinic anhydride or pyromellitic dianhydride, and in that, in reaction (b), said organic compound is trimethylolpropane, pentaerythritol, dipentaerythritol, 2-amino-2-methylpropanol, tris-hydroxymethyl aminomethane or a polyisobutenyl trimethylolpropane or pentaerythritol polyisobutenyl succinate. 6. Composition according to one of claims 1 to 5, characterized in that, in reaction (a) said alkenylsuccinimide and said anhydride or dianhydride are reacted in a molar ratio of 0.25 / 1 to 20/1, at a temperature of 20 to 200 ° C in a solvent comprising at least one mineral oil. 7. Composition according to claim 6, characterized in that said solvent further comprises an aromatic solvent. 8. Composition according to one of claims 1, 2, 4 and 5, characterized in that, in reaction (a), said alkenylsuccinimide and said anhydride or dianhydride are reacted in a molar ratio of 0.25 / 1 at 20/1, at a temperature of 20 to 200 ° C in a solvent comprising at least one mineral oil, and in that in reaction (b), said organic compound is reacted with the product of reaction (a) in a proportion corresponding to a molar ratio of said organic compound to said anhydride or dianhydride from 0.25 / 1 to 4/1 and at a temperature of 100 to 200 ° C, reactions (a) and (b) being carried out in a solvent comprising at least mineral oil. 9. Composition according to claim 8, characterized in that said solvent further comprises an aromatic solvent. 10. Lubricating composition characterized in that it comprises a major proportion of lubricating oil and a proportion of 0.1 to 20% by weight of an additive composition according to one of claims 1 to 9.