FR2471390A1 - Terpolymer from acrylic! ester, di:isobutylene! - and di:carboxylic acid deriv., as low temp. flow improver for hydrocarbon oils - Google Patents

Abstract

A terpolymer consists of (A) 10-94 mols.% of acrylic ester units of formula (-CH2- C(R')(COOR"))- where R' is H or CH3 and R" is 1-30C alkyl, (B) 3-65 mols.% of units derived from dicarboxylic acids and of formula (I), (II) or (III) where R"' and R"" are H or CH3; X and Y are OH, OR", OR""', NH2 or NHR""'; and R""' is a monovalent gp. derived from a cpd. with at least 1 OH and/or amine gp., and (C) 3-40 mols.% of a diisobutylene unit of formula -(CH2-C(CH3)(CH2-C(CH3)3). The mol. wt. is 500-250,000. The polymers are used in lubricants and hydrocarbon oils, e.g. gas oils, domestic fuel oils, and crude petroleum, esp. in heavy oils, to improve flow at low temp. The diisobutylene units improve the solubility in hydrocarbon oils. The dicarboxylic acid units can be reacted with (poly)amino and/or (poly)-OH cpds. to improve the dispersant effect. The terpolymers are cheaper than acrylic ester polymers.

Description

 The present invention relates to novel terpolymers useful in particular as additives for improving the low temperature flow properties of lubricating oils. It also relates to the lubricating oil compositions containing them.

 Lubricating oil compositions suitable for internal combustion engines and automatic transmissions require a combination of base oil additives capable of exhibiting various properties in addition to their lubricity. Such properties include lowering the freezing temperature or the point of freezing of the oil, thermal stability and oxidation resistance, inhibition of rust and corrosion, dispersion of carbonaceous deposits and insoluble materials formed by the combustion of the fuel and the oxidation of the oil, the neutralization of the acidic materials formed by the oxidation of the oil and the improvement of the viscosity index.

 It is an object of the present invention to provide an additive for improving the flow properties of low temperature lubricating oils, in particular by lowering their freezing or freezing point. It also aims to provide a multifunctional additive for lubricating oils, which provides a desirable combination of properties, without prejudice to the individual property of lowering the flow temperature, such as improving the detergency and dispersant and viscosity index.

 A wide variety of compositions comprising copolymers derived from the addition reaction of alpha-olefins and dicarboxylic alkenes have been described in the literature, which are then esterified with long-chain linear saturated alcohols to render the copolymers suitably soluble in hydrocarbon oils, and then polyamine compounds are added to provide dispersants or viscosity index improvers for the lubricants.

 Moreover, the activity of lowering the freezing temperature or the point of setting of the lubricating oils exerted by polymers of acrylic esters is known and it is known that a factor having a particularly great influence in this case, is the length of the side alkyl chains, the presence of a sufficient number of long lateral alkyl chains being apparently determining to obtain a satisfactory solubilization of the additive in the hydrocarbon oils.

 Finally, it is also known that although it is easy to obtain copolymers of acrylic esters with certain alpha-olefins such as ethylene or propylene, it is impossible to obtain copolymers of acrylic esters containing a significant amount of diisobutylene, given the low reactivity of the latter monomer.

 It has now been found that copolymers of acrylic esters containing a large amount of diisobutylene can easily be obtained if a quantity of ethylenically unsaturated dicarboxylic anhydride at least equimolar to that of diisobutylene is added to the monomer mixture. .

 In addition, it has been found that the terpolymers thus obtained have a high efficiency in improving the flow properties of cold lubricating oils, the presence of diisobutylene units in these additives increasing their solubility in hydrocarbon oils.

 Another advantage of the terpolymer additives of the invention, with respect to the anticongelating additives of the prior art, based on polymers of acrylic esters, lies in the possibility of also improving the dispersing action, the presence of carboxylic anhydride units in the terpolymers of the invention for the subsequent addition of (poly) and / or poly-) hydroxylated compounds.

 Finally, the use of these terpolymers as additives combining improved properties of reducing the freezing temperature or the setting point to those of a dispersing agent for lubricants is advantageous from the economic point of view since on the one hand 1 incorporation of large quantities of diisobutylene and maleic anhydride into the acrylic esters contributes to reducing the final price of the additive without this being to the detriment of its properties, and that on the other hand, the dispersing properties of the anti-freeze additive can reduce or eliminate the additional use of conventional dispersant additives lubricating oil formulations.

 The terpolymers of the invention may be defined generally as comprising units derived from at least one acrylic ester of at least one ethylenically unsaturated ap-dicarboxylic compound and diisobutylene; these terpolymers being optionally reacted subsequently. with at least one compound (poly -) - amine and / or (poly -) - hydroxylated.

dans laquelle R1 représente un atome d'hydrogène ou un radical méthyle et R2 représente un radical alkyle de 1 à 30, de préférence de 4 à 18 atomes de carbone, ou un mélange de tels radicaux;; (B) des motifsiSdicarboxyliques répondant à l'une des formules générales

dans lesquelles R 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, -OR5, -NH2, et -NHR5, 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 formule

The terpolymers of the invention are characterized in particular by the fact that they comprise at least three different types of units, namely (A) acrylic ester units corresponding to the general formula

wherein R 1 represents a hydrogen atom or a methyl radical and R 2 represents an alkyl radical of 1 to 30, preferably 4 to 18 carbon atoms, or a mixture of such radicals; (B) cis-dicarboxylic units having one of the general formulas

in which R 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, -OR5, -NH2, and -NHR5, R5 representing a radical monovalent organic compound derived from a compound containing at least one hydroxyl function and / or at least one amine function; and (C) units corresponding to the formula

The respective proportions of the units (A), (B) and (C) contained in the terpolymers of the invention can vary quite widely.

 Thus, for example, these terpolymers may contain from 20 to 90, and preferably from 40 to 75 mol% of units of formula (A), from 5 to 65, and preferably from 10 to 40 mol% of formula (B) and, from 5 to 40, and preferably, from 10 to 30 mol% of units of formula (C). In general, the molar proportion of units (B) will be at least equal to that of units (C).

The acrylic esters from which the units (A) are derived consist more particularly of compounds corresponding to the general formula
CH2 = C1-COOR2, where R1 and R2 have the same meanings as explained above. Examples that may be mentioned include acrylates and methacrylates of methyl, propyl, butyl, 2-ethylhexyl decyl, dodecyl, hexadecyl, octadecyl and eicosyl. Advantageously, butyl acrylate or methacrylate can be used, as can acrylates and methacrylates of industrial cuts of alcohols containing on average 12 carbon atoms (acrylate or lauryl methacrylate) or 18 carbon atoms (acrylate or methacrylate). stearyl).

The ethylenically unsaturated β-dicarboxylic compounds from which the units (B) are derived consist more particularly of the anhydrides or the Mae-liquefumaric, citraconic or mesaconic acids, or the corresponding derivatives having at least one ester or amide function, or else imides (possibly N substituted) corresponding; most often the malefic compounds will be used
The compound giving rise to the units (e) is essentially diisobutylene.

 The number average molecular weight of the terpolymers of the invention measured by tonometry or osmometry, is generally between 500 and 250,000, and preferably between 3000 and 70,000.

 The terpolymers of the invention may be prepared according to conventional free radical polymerization methods, for example, in the presence of an azobisisobutyronitrile or peroxide initiator, in bulk, or in solution in a hydrocarbon solvent, and preferably in a lubricating oil.

 Suitable proportions of the various monomers are used: in general, a molar proportion of ethylenically unsaturated β-dicarboxylic compound (e.g. maleic anhydride) at least equal to the molar proportion of diisobutylene is used.

 If it is desired to obtain terpolymers of the invention in a form such that at least a part of the units (B) have ester, amide or imide functions, it is possible to then bring the reaction mixture into reaction with a compound. (poly) -amino and / or (poly) -hydroxy, at a temperature generally between 80 and 1600C (optionally in the presence of a small amount of a hydrocarbon phase-soluble acid, when the compound is essentially (poly) - hydroxylated).

 In order to obtain good dispersivity qualities which are stable to heat while maintaining a satisfactory solubility of the terpolymers in the lubricating oil, the (poly) -amine and / or (poly) -hydroxylated compound will be chosen, preferably from 3-dimethylaminopropylamine, triethylene tetramine, tetraethylenepentamine, 1-amino-2-pyridine, diethylethanolamine, diethanolamine, cyano-1-guanidine, trimethylolpropane, glycerol or pentaerythritol.

 According to a particularly preferred embodiment of the process for preparing the additive of the invention, a concentrated solution containing approximately 10 to 40% by weight of terpolymer is prepared directly in a solvent consisting of a suitable oil, for example an oil. neutral mineral or a lubricating oil having a viscosity of between about 75 and about 350 universal Saybolt seconds at 37.80C.

 The soluble terpolymers of the invention can be incorporated into lubricating oils (for example lubricating oils for automotive engines or for transmissions) at various concentrations, generally between about 0.01 and 4% by weight, preferably 0.5 to 2% by weight of the total lubricating composition.

 Lubricants to which the terpolymers of the present invention can be included include not only hydrocarbon or hydrorefined oils from petroleum, asphthaltic sand, shale or coal, but also synthetic oils, such as alkylene or alkali polymers. alkylene oxide, alkylbenzenes, dialkylbenzenes and polyphenyls. In a preferred manner, the oils will be naphthenic, paraffinic bases or mixtures thereof.

 The additive will conveniently be provided in a prediluted form comprising for example from 10 to 60 parts by weight, preferably about 40 parts by weight of the additive, dissolved in 90 to 40 parts by weight, preferably about 60 parts by weight, mineral lubricating oil, with or without the presence of other additives.

 It is also obvious that, within the scope of the invention, it is also possible to add, in the lubricating oil compositions of the invention, other commonly used additives, such as, for example, corrosion inhibitors, antiemulsifiers, antioxidants, detergents or dispersants, or viscosity index improvers. In particular, probably because of the combination of suitable ester and olefin units, the terpolymers of the invention exhibit improved compatibility and anti-freeze efficiency in the presence of polyolefinic viscosity additives, additives used more and more often in the lubricants.

 The following nonlimiting examples illustrate embodiments of the invention.

Example 1
A solution containing 22.5 g (6665 10-3 mol) of stearyl methacrylate, 10 g. (89-, 210-3 mol) of diisobutylene and 7.5 g. (76.5 × 10 -3 mol) of maleic anhydride in 80 cm 3 of toluene is heated to 900 ° C. Gradually added (rate of addition éyale d10 cm3 / h) a solution containing 0.3 g. of azobisisobutyronitrile in 20 cm3 of toluene and the mixture is stirred at 900C for 4 hours.

 A sample of the reaction mixture is precipitated in an excess of methyl alcohol; the precipitate is isolated by filtration and dried under reduced pressure to constant weight.

 The terpolymer obtained contains about 54 mole percent stearyl methacrylate, 20 mole percent diisobutylene, and 26 mole percent maleic anhydride; it has a number average molecular weight of 10,200.

 To present the terpolymer in a pre-diluted form, the toluene solution is mixed with a lubricating oil, for example 200 N or 350 N, and the toluene is then evaporated under reduced pressure to constant weight.

Example 2
At 13 g. of the terpolymer of Example 1, dissolved in 50 cm 3 of a 200 N lubricating oil, 2 g are added. of dimethylaminopropylamine and the mixture is stirred for 4 hours at 1500C.

 The infrared spectrum of the solution thus obtained shows the disappearance of the absorption band due to anhydride type C = O bonds, initially located at about 1775 cm -1; on the other hand, we observe the appearance of a new absorption band located around 1705-1695 cm-1 and attributed to the C = O bonds of imide type.

Example 3 A solution containing 14 g. (41.4 moles) stearyl methacrylate, 6 g. (32.6 × 10 -3 moles) of 2-ethyl hexyl acrylate, 7 g. (62.5 × 10-3 moles) diisobutylene and 10 grams. (10.2 moles) fumaric anhydride in 100 cc of a 100 N lubricating oil is heated at 800C for 2 hours in the presence of 0.4 g. azobisisobutyronitrile, then at 100 C for 2 hours. Then 1.5 g is added. of tetraethylenepentamine and the mixture is stirred for 2 hours at 1400C.

Example 4
A mixture of 13 g. (51.2 10 -3 moles) of lauryl methacrylate, 11 g. (32.5-10 -3 moles) of stearyl methacrylate, 6 g. (53.5 10-3 moles) of diisobutylene and 8 g. (81.6 × 10 -3 mol) of maleic anhydride is dissolved in 140 cm3 of toluene. 0.8 g is added. of dicumyl peroxide and the mixture is heated at 120 ° C. for 2 hours. After the addition of 8 g. of diethanolamine, the heating is continued at 1000C for 4 hours. An additive concentrate in a lubricating oil is prepared by adding 50 cm3 of 350 N oil and evaporating toluene under reduced pressure to constant weight.

Example 5 A mixture of 40 g. (12.3 10-2 2 moles) of stearyl acrylate, 10 g. (70.4 10-3 mol) butyl methacrylate, 5 g. (0.05 mole) methyl methacrylate, 25 g. (22.3 10-2 mol) diisobutylene and 30 g. (30.6 × 10 -2 mol) of maleic anhydride is heated at 900 ° C. for 3 hours, in the presence of 1.1 g. of benzoyl peroxide, then at 110 ° C. 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 1000C, in 350 cm3 of a 200 N lubricating oil. 28 g are added thereto. of dimethylaminopropylamine and the solution is stirred at 150 ° C. for 4 hours.

Example 6
To a solution of 33 g. (29.4 10-2 mol) diisobutylene and 40 g. (40.8 × 10 -2 mol) of maleic anhydride in 200 cm 3 of dioxane, heated to 700 ° C., a solution of 51 g is added over 4 hours. (15.1 10-2 mol) stearyl methacrylate, 37 g. (14.5 10-2 mol) lauryl methacrylate and 1.6 g. of azobisisobutyronitrile in 200 cm3 of dioxane.

Heating at 700C is continued for another 4 hours.

 Half of the solution is precipitated in an excess of methyl alcohol and the precipitate is isolated by filtration, washed with alcohol and dried under reduced pressure to constant weight. In this way, 74 g is obtained. terpolymer having a number average molecular weight of 4700, the contents of maleic anhydride and diisobutylene being 46 and 24 mol%, respectively.

Example 7
To the remainder of the reaction solution of Example 6 is added 200 cm 3 of a 100 N lubricating oil and the dioxane is distilled under reduced pressure to constant weight.

40 g are added to the residue. trimethylolpropane and 0.6 g.

of para-toluenesulfonic acid and the mixture is heated at 1500C for 4 hours.

The infrared spectrum of the solution shows the disappearance of the absorption at the frequencies corresponding to the bonds
C = O of the anhydride groups, the absorption frequency of the new ester-type C = O bonds formed coincides with that of the C = O ester bonds of the methacrylates, located around 1725-1,735 cm -1.

Example 8
The solutions of the various terpolymers described above were added to several lubricating oils and the lowering of the flow temperature was determined according to the AFMOR NFT 60-105 or ASTM D 97 standard.
As is apparent from the examination of Table 1 below, the terpolymers of the invention are very effective agents for lowering the lubricant flow temperature.

Table 1

<tb> Product <SEP> of <SEP> Percentage <SEP> in <SEP> Wt <SEP> Oil <SEP> Temperature
<tb> the <SEP> example of <SEP><SEP> upproofing <SEP> terpolymer <SEP> OC
<tb><SEP> - <SEP> 0 <SEP><SEP> 200 <SEP> N <SEP> - <SEP> 15
<tb> - <SEP> 0 <SEP> 350 <SEP> N <SEP> 9 <SEP>
<tb><SEP> 1 <SEP> 0.5 <SEP> 200 <SEP> N <SEP> - <SEP> 30
<tb><SEP> 1 <SEP> 0.5 <SEP> 350 <SEP> N <SEP> - <SEP> 27
<tb><SEP> 2 <SEP> 0.5 <SEP> 200 <SEP> N <SEP> - <SEP> 30
<tb><SEP> 3 <SEP> 0.5 <SEP> 350 <SEP> N <SEP> - <SEP> 24
<tb><SEP> 4 <SEP> 0.5 <SEP> 350 <SEP> N <SEP> - <SEP> 30
<tb><SEP> 4 <SEP> 0.3 <SEP> 350 <SEP> N <SEP> - <SEP> 27
<tb><SEP> 5 <SEP> 0.5 <SEP> 200 <SEP> N <SEP> - <SEP> 35
<tb><SEP> 6 <SEP> 0.5 <SEP> 200 <SEP> N <SEP> - <SEP> 26
<tb><SEP> 6 <SEP> 0.5 <SEP> 350 <SEP> N <SEP> - <SEP> 24
<tb><SEP> 7 <SEP> 0.5 <SEP> 200 <SEP> N <SEP> - <SEP> 26
<Tb>
The dispersancy power of certain anti-freeze additives described above was determined according to the spot method described by GATES VA et al. in SAE Preprint n0572 (1955) or by A. Schilling in "Motor Oils and Motor Lubrication" Edt.Technip, Volume I, p.89 (1962).

According to this method, the ratio of the diameters is established after 24 hours, of the two concentric spots formed by depositing a drop of oil containing 2% by weight of additive and 1% by weight of sludge, on a sheet of filter paper. ,
The results are determined at 200C (A), 2000C (B) and after cooling to 200C (C).

 As indicated by the results summarized in Table 2 below, the terpolymers which lower the flow temperature of the lubricants according to the invention can also be good dispersing agents, which can be used even at the usual low concentrations of point-depressing additives. flow.

Table 2

<tb> Product <SEP> of <SEP> Example <SEP> Can <SEP> Dispersing
<tb><SEP> (A) <SEP> - (B) <SEP> (c)
<tb><SEP> 2 <SEP> 0.80 <SEP> 0.75 <SEP> 0.78
<tb><SEP> 2+ <SEP> 0.68 <SE> 0.69 <SEP> 0.70
<tb><SEP> 3 <SEP> 0.82 <SEP> 0.77 <SEP> 0.79
<tb><SEP> 4 <SEP> 0.75 <SEP> 0.71 <SEP> 0.71
<tb><SEP> 5 <SEP> 0.83 <SEP> 0.81 <SEP> 0, <SEP> 81
<tb><SEP> 5+ <SEP> 0.72 <SEP>0; 71 <SEP> 0.71
<tb><SEP> 7 <SEP> 0.74 <SEP> 0.76 <SEP> 0.78
<Tb>
In both cases, 0.5% by weight of
terpolymer.

Claims (17)

1. terpolymer soluble in lubricating oils, characterized in that it comprises  A / acrylic ester units having the formula

 said terpolymer having a number average molecular weight of 500 to 250,000.

 and (C) patterns of the formula  or R3 and R4, which are 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, -OR5, -NH2 and -BLACKS, where R5 represents an organic radical; monovalent derivative of a compound containing at least one function selected from hydroxyl functions and amine functions

 B / dicarboxylic units having the general formula in which R 1 represents a hydrogen atom or a methyl radical and R 2 represents an alkyl radical of 1 to 30 carbon atoms <tb> <SEP> e00R2 <tb> <SEP> 4 <SEP> 2 <SEP> 1 <SEP> 9 <tb> General <SEP> R1 2. Terpolymer according to claim 1, characterized in that the units (A) represent from 20 to 90 mol%, the units (B) from 5 to 65 mol%, and the units (C) from 5 to 40% by weight. in moles of all the units of the terpolymer. 3. terpolymer according to claim 2, characterized in that the units (A) represent from 40 to 75 mol%, the units (-B) from 10 to 40 mol% and the units (C) from 10 to 30% in moles of all the units of the terpolymer. 4. terpolymer according to one of claims 1 to 3, characterized in that the number average molecular weight is 3,000 to 70,000. 5. terpolymer according to one of claims 1 to 4, characterized in that the units (A) derived from at least one acrylate or alkyl methacrylate of 4 to 18 carbon atoms. 6. Terpolymer according to claim 5, characterized in that the units (A) are derived from at least one acrylate or methacrylate chosen from acrylates and methacrylates of butyl, lauryl or stearyl. Terpolymer according to one of claims 1 to 6, characterized in that the units (B) are derived from at least one compound selected from maleic, fumaric, citraconic and mesaconic anhydrides, the corresponding acids, the corresponding derivatives having at least one less an ester or amide function and the corresponding imides. 8. Terpolymer according to claim 7, characterized in that the units (B) are derived from maleic anhydride. 9. terpolymer according to one of claims 1 to 8, characterized in that the units (C) derive from diisdoutylene.  10. terpolymer according to one of claims 1 to 9, characterized in that the molar proportion of the units (B) is at least equal to that of the units (C). 11. Process for the preparation of a terpolymer according to one of claims 1 to 10, characterized in that, under polymerization conditions, in the presence of a free-radical generating compound, suitable proportions of at least one acrylic ester, at least one ethylenically unsaturated dicarboxylic compound, and diisobutylene. 12. The method of claim 11, characterized in that lion involves a molar proportion of p-dicarboxylic compound ethylenically unsaturated at least equal to that of diisobutylene. 13. Method according to one of claims 11 and 12, characterized in that the polymerization reaction is carried out in a lubricating oil or a neutral mineral oil. 14. Method according to one of claims 11 to 13, characterized in that in the polymerization step the ethylenically unsaturated t-dicarboxylic compound involved is an anhydride and in that it implements a subsequent step reaction with a suitable proportion of at least one compound having at least one selected from hydroxyl functions and amine functions, so as to esterify, amidify or imidify at least a portion of the anhydride units present. 15. Lubricating oil composition, characterized in that it comprises a major proportion of at least one lubricating oil and a minor proportion of at least one terpolymer according to one of claims 1 to 10. 16. Composition according to claim 15, characterized in that the terpolymer proportion is 0.01 to 4% by weight. 17. Composition according to claim 16, characterized in that the proportion of terpolymer is 0.5 to 2% by weight.