DE69419456T2 - Fatty acid ester treated with a pour point, as a biodegradable internal combustion engine fuel - Google Patents

Description

The present invention relates to interesterified animal oils and vegetable oils which contain at least one pour point depressant and one antioxidant. In addition to pour point depressants and antioxidants, the interesterified natural oil can also contain additional additives and a normally liquid fuel.

The successful use of esters of transesterified natural oils as environmentally friendly, i.e. biodegradable, base fluids for industrial applications and also as fuel additives when mixed with normally liquid fuels depends on improving their viscosity properties at low temperatures. For example, a methyl ester obtained from the transesterification of rapeseed oil is suitable as an environmentally friendly diesel fuel. However, this methyl ester has a pour point of -12ºC and solidifies at -13.6ºC, which leads to clogged filters and engine damage. In order to take advantage of the biodegradability of transesterified esters of natural oils, a lowering of the pour point is necessary.

U.S. Patent 2,243,198 (Dietrich, May 27, 1941) relates to non-viscous, normally liquid hydrocarbon oils and, more particularly, to the preparation of fuel oils having improved flow properties under low temperature conditions. The flow properties of fuel oil are improved by the addition of a hydrogenated castor oil derivative to a non-viscous, normally liquid hydrocarbon oil. A hydrogenated castor oil derivative is defined as the product obtained by reacting hydrogenated castor oil with either its own hydroxyl groups or with another organic compound selected from the classes of alcohols, aldehydes, acids, isocyanates and isothiocyanates.

US-PS 4,364,743 (Erner, December 21, 1982) relates to a fuel source for oil combustion devices, which is itself a fuel or can be mixed with petroleum middle distillates. Fatty acids of the general formula

can provide such a fuel, in which

(a) the radical R is (1) an alkyl group having 1 to 12 carbon atoms, (2) an alkoxyalkyl group, wherein the alkoxy part contains 1 to 4 carbon atoms and the alkyl part is an ethyl or propyl group, (3) a cyclopentyl or cyclohexyl group and (4) a hydroxyethyl and hydroxypropyl group;

(b) n = 11-22;

(c) a = 2n+1, 2n-1, 2n-3, 2n-5 or 2n-7; and

(d) x has the value 0 or 1.

U.S. Patent 4,575,382 (Sweeney et al., March 11, 1986) relates to a middle distillate fuel containing a vegetable oil having improved thermal stability properties. The vegetable oils that can be used include soybean oil, peanut oil and sunflower oil.

US Patent 4,695,411 (Stern et al., September 22, 1987) relates to a process for producing a major portion of ethyl esters useful as gas oil substitute motor fuel by transesterification of an animal or vegetable oil optionally containing free acids.

US-PS 5,160,506 (Schur et al., November 3, 1992) relates to a liquid fuel mixture comprising a C3 and/or at least one C4 alkane and at least one oil component and optionally at least one additive, a process for its preparation and its use for two-stroke engines.

WO 92/11345 relates to mixtures of fatty acid lower alkyl esters with improved cold stability, containing

a) 58-95% by weight of at least one ester with an iodine number of 50-150, derived from fatty acids with 12-22 carbon atoms and lower aliphatic alcohols with 1-4 carbon atoms,

b) 4-40% by weight of at least one ester of fatty acids with 6-14 carbon atoms and lower aliphatic alcohols with 1-4 carbon atoms and

c) 0.1-2 wt.% of at least one polymeric ester.

According to the present invention there is provided a composition comprising:

(A) Esters from the transesterification of at least one animal or vegetable triglyceride oil of the general formula

with an alcohol R⁴OH, where the radicals R¹, R² and R³ are aliphatic groups having 6 to 24 carbon atoms and the radical R⁴ is an aliphatic group having 1 to 10 carbon atoms;

(B) a pour point depressant and

(C) (4) an antioxidant comprising (a) and (b) and (c) according to claim 1.

In addition to components (A), (B) and (C)(4), the composition may also comprise an additive (C)(1)-(3) and/or (D) a normally liquid fuel.

Various preferred features and embodiments of the invention are illustrated below in a non-limiting manner.

(A) The interesterified esters

In the practice of this invention, a natural oil, including animal fat or vegetable oils, is reacted with an alcohol to obtain interesterified esters. These natural oils include triglycerides of the general formula

in which R¹, R² and R³ are aliphatic hydrocarbyl groups containing 6 to 24 carbon atoms. The term "hydrocarbyl group" as used in the specification and claims refers to a group containing a carbon atom directly bonded to the rest of the molecule. The aliphatic hydrocarbyl groups include the following:

(1) Aliphatic hydrocarbon groups; i.e., alkyl groups such as heptyl, nonyl, undecyl, tridecyl, heptadecyl; alkenyl groups with a single double bond such as heptenyl, nonenyl, undecenyl, tridecenyl, heptadecenyl, heneicosenyl; alkenyl groups with 2 or 3 double bonds such as 8,11-heptadecadienyl and 8,11,14-heptadecatrienyl. All isomers of these are included, but straight-chain groups are preferred.

(2) substituted aliphatic hydrocarbon groups; i.e., groups containing non-hydrocarbon substituents which, in the context of this invention, do not alter the predominantly hydrocarbon character of the group. Suitable substituents are known; examples are hydroxy, carbalkoxy (especially lower carbalkoxy) and alkoxy (especially lower alkoxy) groups, where the term "lower" refers to groups having less than 7 carbon atoms.

(3) Heterogroups; i.e., groups which, while having predominantly aliphatic hydrocarbon character within the context of this invention, contain atoms other than carbon present in a chain or ring otherwise composed of aliphatic carbon atoms. Suitable heteroatoms are known and include, for example, oxygen, nitrogen and sulfur.

Animal fats including beef tallow oil and menhaden oil are suitable. Suitable vegetable oils include sunflower oil, cottonseed oil, safflower oil, corn oil, soybean oil, canola oil, meadowfoam oil or any of the above-mentioned vegetable oils that are genetically modified so that the monounsaturated content exceeds the normal value. For example, a synthetic triglyceride made by reacting 1 mole of glycerin with 3 moles of oleic acid has an oleic acid content of 100% and therefore a monounsaturated content of 100%. Normal sunflower oil has an oleic acid content of 25-30%. By genetically modifying the sunflower seeds, a sunflower oil with an oleic acid content of 60% to 90% can be obtained.

Preferably, the monounsaturated character is derived from an oleyl residue, i.e. R¹CO, R²CO and R³CO is the residue of oleic acid. The preferred triglyceride oils are high oleic triglyceride oils (at least 60%). Typical high oleic vegetable oils used in the present invention include high oleic safflower oil, high oleic corn oil, high oleic rapeseed oil, high oleic sunflower oil, high oleic soybean oil, high oleic cottonseed oil and high oleic palm oil.

A preferred high oleic vegetable oil is high oleic sunflower oil obtained from Helianthus sp. This product is available from SVO Enterprises, Eastlake, Ohio as Sunyl® High Oleic Sunflower Oil. Sunyl 80 is a high oleic triglyceride where the acid residues comprise 80% oleic acid. Another preferred high oleic vegetable oil is high oleic canola oil obtained from Brassica compestris or Brassica napus and is also available from SVO Enterprises as RS® High Oleic Canola Oil. RS80 refers to a canola oil where the acid residues comprise 80% oleic acid.

The alcohols used to form the transesterified esters have the general formula R⁴OH, in which the radical R⁴ is an aliphatic group having 1 to 24 carbon atoms. The radical R⁴ can be straight-chain or branched and saturated or unsaturated. Examples of The alcohols used to form the transesterified esters have the general formula R⁴OH, in which the radical R⁴ is an aliphatic group having 1 to 24 carbon atoms. The radical R⁴ can be straight-chain or branched-chain and saturated or unsaturated. Examples of alcohols are: methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol and the isomeric butyl, pentyl, hexyl, heptyl, octyl, nonyl, dodecyl, pentadecyl and octadecyl alcohols. The alcohol is preferably methyl alcohol.

The transesterification generally takes place by mixing at least 3 moles of R4OH per 1 mole of triglyceride. A catalyst, if used, comprises alkali metal or alkaline earth metal alkoxides having 1 to 6 carbon atoms. Preferred catalysts are sodium or potassium methoxide, calcium or magnesium methoxide, the ethoxides of sodium, potassium, calcium or magnesium, and the isomeric propoxides of sodium, potassium, calcium or magnesium. The most preferred catalyst is sodium methoxide.

The transesterification conveniently takes place at a temperature from room temperature to the decomposition temperature of any reactant or product. Usually the upper temperature limit is not higher than 150ºC and preferably not higher than 120ºC.

During transesterification, mixed esters are obtained according to the following reaction equation:

Transesterification is an equilibrium reaction. To shift the equilibrium to the right, it is usually necessary to either use a large excess of alcohol or to remove the glycerol formed. If an excess of alcohol is used,

TEXT MISSING

Example A-1

A 12 liter four-necked flask is charged with 7056 parts (8 moles) of high oleic rapeseed oil, 1280 parts (40 moles) of absolute methyl alcohol and 70.5 parts (1.30 moles) of sodium methoxide. The contents are heated to a reflux temperature of 73ºC and held at this temperature for 3 hours and 76 parts (0.65 moles) of 85% phosphoric acid are added dropwise over 0.4 hour to neutralize the catalyst. Excess methyl alcohol is then removed by heating to 100ºC while blowing with nitrogen at 5.66 L/h (0.2 cfh) and later under a reduced pressure of 40 mbar (30 mm Hg). The contents are filtered to yield 6952 parts of the interesterified methyl ester of high oleic rapeseed oil.

Example A-2

The procedure of Example A-1 is essentially repeated except that the high oleic rapeseed oil is replaced by high oleic sunflower oil to give the interesterified methyl ester of high oleic sunflower oil.

Example A-3

A 5-liter, four-necked flask is charged with 759 parts (12.5 moles) of isopropyl alcohol. At room temperature, 5.75 parts (0.25 moles) of elemental sodium are slowly added. When the sodium is completely reacted, 2205 parts (25 moles) of high oleic sunflower oil are added. The contents are heated to 85ºC and held at that temperature for 4 hours, after which the catalyst is neutralized with 9.67 parts (0.083 moles) of 85% phosphoric acid. The contents are stripped to 120ºC at 36 mbar (27 mm Hg) to yield 2350 parts of the interesterified isopropyl ester of high oleic sunflower oil.

Example A-4

The procedure of Example A-3 is essentially repeated except that the catalyst is prepared by reacting 690 parts (15 moles) of absolute ethyl alcohol with 6.9 parts (0.3 moles) of sodium metal. The product obtained is the interesterified ethyl ester of high oleic sunflower oil.

Example A-5

The procedure of Example A-3 is essentially repeated except that the catalyst is prepared by reacting 910 parts (15 moles) of n-propyl alcohol with 6.9 parts (0.3 moles) of sodium metal. The product obtained is the interesterified n-propyl ester of high oleic sunflower oil.

Example A-6

The procedure of Example A-3 is essentially repeated except that the catalyst is prepared by reacting 1114.5 parts (15 moles) of n-butyl alcohol with 6.9 parts (0.3 moles) of sodium metal. The product obtained is the interesterified n-butyl ester of high oleic sunflower oil.

Example A-7

The procedure of Example A-3 is essentially repeated except that the catalyst is prepared by reacting 1300 parts (12.5 moles) of n-hexyl alcohol with 5.75 parts (0.25 moles) of sodium metal. The product obtained is the interesterified n-hexyl ester of high oleic sunflower oil.

Example A-8

Using the catalyst prepared in Example A-3, safflower oil is transesterified with isopropyl alcohol to obtain the transesterified isopropyl esters of safflower oil.

Example A-9

Using the catalyst prepared in Example A-4, cottonseed oil is transesterified with ethyl alcohol to obtain the transesterified ethyl esters of cottonseed oil.

Example A-10

Using the catalyst prepared in Example A-6, corn oil is transesterified with n-butyl alcohol to obtain the transesterified n-butyl esters of corn oil.

Example A-11

The procedure of Example A-9 is essentially repeated except that beef tallow oil is used in place of cottonseed oil. The product obtained is the interesterified ethyl ester of beef tallow oil.

Example A-12

The procedure of Example A-10 is essentially repeated except that menhaden oil is used instead of corn oil. The product obtained is the interesterified n-butyl ester of menhaden oil.

Example A-13

The procedure of Example A-1 is essentially repeated except that rapeseed oil is used instead of high oleic rapeseed oil. The product obtained is the interesterified methyl ester of rapeseed oil.

Example A-14

The procedure of Example A-1 is essentially repeated except that soybean oil is used instead of high oleic rapeseed oil. The product obtained is the interesterified methyl ester of soybean oil.

(B) The pour point depressant

A disadvantage of using interesterified esters is the difficulties associated with the solidification of the interesterified esters at low temperatures (below -10ºC). These difficulties arise from a natural stiffening of the interesterified esters at low temperatures, analogous to the stiffening of honey or molasses at a reduced temperature. To maintain the "pourability" or "flowability" of the interesterified esters, a pour point depressant is added to the oil.

Pour point depressants (PPD) useful in this invention are carboxyl group-containing copolymers in which many of the carboxyl groups are esterified and the remaining carboxyl groups, if present, are neutralized by reaction with amino compounds; acrylate polymers, nitrogen-containing acrylate polymers, and methylene-linked aromatic compounds.

Carboxyl group-containing copolymers

This PPD is an ester of a carboxyl group-containing copolymer, the copolymer having a reduced specific viscosity of 0.05 to 2, the ester being substantially free of titratable acid, i.e. i.e., at least 90% esterified, and characterized by the presence of attached polar groups within the polymeric structure: (i) a relatively high molecular weight carboxylic acid ester group, wherein the carboxylic acid ester group has at least 8 to 24 aliphatic carbon atoms in the ester group, (ii) a relatively low molecular weight carboxylic acid ester group having no more than 7 aliphatic carbon atoms in the ester group, and optionally (iii) a carbonyl polyamino group derived from a polyamino compound having a primary or secondary amino group, wherein the molar ratio of (i): (ii) is (1-20): 1, preferably (1-10): 1 and wherein the molar ratio of (i): (ii): (iii) is (50-100): (5-50): 0.1-15).

An essential characteristic of this ester is that the ester is a mixed ester, i.e., an ester in which both a high molecular weight ester group and a low molecular weight ester group are present in combination, particularly in the ratio mentioned above. Such combined presence is critical with respect to the viscosity properties of the mixed ester, both in terms of its viscosity modifying properties and its thickening effect on lubricant compositions in which the ester is used as an additive.

With regard to the size of the ester groups, it is emphasized that an ester group is represented by the general formula

-C(O)(OR)

and that the number of carbon atoms in an ester group is the combined total number of carbon atoms of the carbonyl group and the carbon atoms of the ester group, i.e., the (OR) group.

An optional property of this ester is the presence of a polyamino group derived from a single amino compound, that is, a compound in which at least one primary or secondary amino group and at least one monofunctional amino group is present. Such polyamino groups improve the dispersibility of such esters in lubricant compositions and additive concentrates for lubricant compositions when they are present in the mixed esters in the proportions specified above.

Another important characteristic of the mixed ester is the extent of esterification relative to the extent of neutralization of the unesterified carboxyl groups of the carboxyl group-containing copolymer by converting them to the optional polyamino-containing groups. For simplicity, the relative proportions of the high molecular weight ester groups to the low molecular weight ester groups and to the polyamino groups are expressed in molar ratios of (50-100):(5-50)(0.1-15). The preferred ratio is (70-85):(15-30):(3-4). It is to be noted that the bond described as a carbonyl-polyamino group can be imide, amide or amidine and insofar as any of these bonds are used within the present invention, the term "carbonyl-polyamino" is considered to be a convenient collective term. In a particularly advantageous embodiment of the invention, such a bond is an imide or predominantly imide.

Another important characteristic of the mixed ester is the molecular weight of the carboxyl group-containing copolymer. For convenience, the molecular weight is expressed as the "reduced specific viscosity" of the copolymer, which is a widely accepted term for indicating the molecular size of a polymeric substance. The reduced specific viscosity (abbreviated RSV) used here is the value of according to the formula

RSV = Relative Viscosity - 1 / Concentration

where the relative viscosity is determined by measuring the viscosity of a solution of 1 g of the copolymer in 10 ml of acetone and the viscosity of acetone at 30ºC ± 0.02ºC using a dilution viscometer. To calculate the RSV using the above formula, the concentration is adjusted to 0.4 g of the copolymer per 100 ml of acetone. A more detailed discussion of reduced specific viscosity, also known as specific viscosity, and its relationship to the average molecular weight of a copolymer can be found in Paul J. Flory, Principles of Polymer Chemistry, 1953 edition, pages 308ff.

While copolymers with a reduced specific viscosity of 0.05 to 2 are present in the mixed ester, the preferred copolymers have a reduced specific cal viscosity of 0.1 to 1. In most cases, copolymers with a reduced specific viscosity of 0.1 to 0.8 are particularly preferred.

From a standpoint of utility, both commercial and economic, preferred are esters in which the high molecular weight ester group contains 8 to 24 aliphatic carbon atoms and the low molecular weight ester group contains 3 to 5 carbon atoms and the carbonylamino group is derived from a primary aminoalkyl-substituted tertiary amine, particularly from heterocyclic amines. Specific examples of these high molecular weight carboxylic acid ester groups, i.e., the (OR) group of the ester residue (i.e., -(O)(OR)), include heptyloxy, isooctyloxy, decyloxy, dodecyloxy, tridecyloxy, tetradecyloxy, pentadecyloxy, octadecyloxy, eicosyloxy, tricosyloxy and tetracosyloxy. Specific examples of low molecular weight groups include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, sec-butyloxy, isobutyloxy, n-pentyloxy, neopentyloxy, n-hexyloxy, cyclohexyloxy, cyclopentyloxy, 2-methylbutyl-1-oxy and 2,3-dimethylbutyl-1-oxy. In most cases, alkoxy groups of appropriate size include the high and low molecular weight ester groups. Polar substituents may be present in such ester groups. Examples of polar substituents are chlorine, bromine, ether and nitro groups.

Examples of the carbonylpolyamino group include those derived from polyamino compounds having a primary or secondary amino group and at least one monofunctional amino group, such as a tertiary amino group or a heterocyclic amino group. Such compounds may thus be tertiary amino-substituted primary or secondary amines or other substituted primary or secondary amines in which the substituent is derived from pyrroles, pyrrolidones, caprolactams, oxazolidones, oxazoles, thiazoles, pyrazoles, pyrazolines, imidazoles, imidazolines, thiazines, oxazines, diazines, oxycarbamyl, thiocarbamyl, uracils, hydantoins, thiohydantoins, guanidines, ureas, sulfonamides, phosphoramides, phenothiazines and amidines. Examples of such polyamino compounds include dimethylaminoethylamine, dibutylaminoethylamine, 3-dimethylamino-1-propylamine, 4-methylethylamino-1-butylamine, pyridylethylamine, N-morpholinoethylamine, tetrahydropyridylethylamine, bis-(dimethylamino)-propylamine, bis-(diethylamino)-ethylamine, N,N-dimethyl-p-phenylenediamine, Pip eridylethylamine, 1-aminoethylpyrazole, 1-(methylamino)pyrazoline, 1-methyl-4-aminooctylpyrazole, 1-aminobutylimidazole, 4-aminoethylthiazole, 2-aminoethylpyridine, o-aminoethyl-N,N-dimethylbenzenesulfamide, N-aminoethylphenothiazine, N-aminoethylacetamidine, 1-amino phenyl-2-aminoethylpyridine and N-methyl-N-aminoethyl-S-ethyldithiocarbamate. Preferred polyamine compounds include the N-aminoalkyl substituted morpholines such as aminopropylmorpholine. For the most part, the polyamino compounds are those compounds which contain only one primary amino or secondary amino group and, preferably, at least one tertiary amino group. The tertiary amino group is preferably a heterocyclic amino group. In some cases, polyamino compounds may contain up to 6 amino groups, although, in most cases, they contain one primary amino group and either one or two tertiary amino groups. The polyamino compounds may be aromatic or aliphatic amines and are preferably heterocyclic amines such as aminoalkyl-substituted morpholines, piperazines, pyridines, benzopyrroles, quinolines, pyrroles, etc. Usually they are amines having 4 to 30 carbon atoms, preferably 4 to 12 carbon atoms. Polar substituents may equally be present in the polyamines.

The carboxyl-containing copolymers essentially include copolymers of alpha, beta-unsaturated acids or anhydrides such as maleic anhydride or itaconic anhydride with olefins (aromatic or aliphatic) such as ethylene, propylene, isobutene or styrene or substituted styrene, wherein the substituent is a hydrocarbyl group having 1 to about 18 carbon atoms. The styrene-maleic anhydride copolymers are particularly suitable. They are obtained by polymerizing equal molar amounts of styrene and maleic anhydride, with or without one or more additional copolymerizable comonomers. Instead of styrene, an aliphatic olefin can be used, such as ethylene, propylene or isobutene. Instead of maleic anhydride, acrylic acid or methacrylic acid or an ester thereof can be used. Such copolymers are known. If a copolymerizable comonomer is used, it should be present in a relatively small amount, e.g., less than 0.3 moles, usually less than 0.15 moles, per mole of either the olefin (e.g., styrene) or the alpha, beta-unsaturated acid or anhydride (e.g., maleic anhydride).

Various processes for the copolymerization of styrene and maleic anhydride are known. For example, the copolymerizable comonomers include the vinyl monomers such as vinyl acetate, acrylonitrile, methyl acrylate, methyl methacrylate, acrylic acid, vinyl methyl ether, vinyl ethyl ether, vinyl chloride and isobutene.

The nitrogen-containing esters of the mixed esters are most conveniently prepared by first esterifying the carboxyl group-containing copolymer with a relatively high molecular weight alcohol and a relatively low molecular weight alcohol to 100%. When the optional component (C) is employed, the high molecular weight alcohol and the low molecular weight alcohol are used to convert at least 50% and not more than 98% of the carboxyl groups of the copolymer into ester groups and then the remaining carboxyl groups are neutralized with a polyamino compound as described above. In order to introduce the appropriate amounts of the two alcohol groups into the copolymer, the ratio of the high molecular weight alcohol to the low molecular weight alcohol used in the process should be within the range of 2:1 to 9:1 on a mole basis. In most cases the ratio is 2.5:1 to 5:1. More than one high molecular weight or low molecular weight alcohol can be used in the process; commercially available alcohol mixtures such as the so-called oxo alcohols can also be used, which comprise, for example, mixtures of alcohols having 8 to 24 carbon atoms. A particularly suitable class of alcohols are the commercially available alcohols or alcohol mixtures comprising decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol and octadecyl alcohol. Other alcohols suitable for use in the process are those which, upon esterification, give the ester groups described above.

The extent of esterification, as indicated above, may range from 50% to 98% conversion of the carboxyl groups of the copolymer to ester groups. In a preferred embodiment, the extent of esterification ranges from 75% to 95%.

Esterification can be accomplished simply by heating the carboxyl group-containing copolymer and the alcohol or alcohols under typical esterification conditions. Such conditions include, for example, a temperature of at least about 80°C, preferably 150-350°C, provided that the temperature is below the decomposition point of the reaction mixture, and removing water from the esterification as the reaction proceeds. Such conditions may optionally include the use of an excess of the alcohol reactant so as to facilitate esterification, the use of a solvent or diluent such as mineral oil, toluene, benzene, xylene or the like, and an esterification catalyst such as toluenesulfonic acid, sulfuric acid, aluminum chloride, boron trifluoride-triethylamine, hydrochloric acid, ammonium sulfate, phosphoric acid, sodium methoxide. These conditions and variations thereof are known in the art.

A particularly suitable esterification process involves first reacting the carboxyl group-containing copolymer with the relatively high molecular weight alcohol and then reacting the partially esterified copolymer with the relatively low molecular weight alcohol. A variation of this process involves initial esterification with the relatively high molecular weight alcohol. Before completion of this esterification, the relatively low molecular weight alcohol is added to the reaction mass so that a mixed esterification is achieved. In each case, it has been discovered that a A two-step esterification process wherein the carboxyl group-containing copolymer is first esterified with the relatively high molecular weight alcohol to achieve 50% to 75% conversion of the carboxyl groups to ester groups and then esterified with the relatively low molecular weight alcohol to achieve the final desired degree of esterification, resulting in products having unusually advantageous viscosity properties.

The esterified copolymer may optionally be treated with a polyamino compound so that substantially all of the unesterified carboxyl groups of the copolymer are neutralized. Neutralization is preferably carried out at a temperature of at least about 80°C, often from 120°C to 300°C, provided that the temperature does not exceed the decomposition point of the reaction mass. In most cases, the neutralization temperature is between 150°C and 250°C. A slight excess of the stoichiometric amount of the amino compound is often desirable in order to make the neutralization substantially complete, i.e., so that no more than 2% of the carboxyl groups originally present in the copolymer remain unneutralized.

The following non-limiting examples illustrate the preparation of the mixed esters of the present invention. All parts and percentages are by weight unless otherwise indicated.

Example (B-1)

A styrene-maleic anhydride copolymer is obtained by preparing a solution of styrene (16.3 parts by weight) and maleic anhydride (12.9 parts) in a benzene-toluene solution (270 parts; weight ratio of benzene to toluene 66.5:33.5) and contacting the solution at 86°C in a nitrogen atmosphere for 8 hours with a catalyst solution prepared by dissolving 70% benzoyl peroxide (0.42 parts) in a similar benzene-toluene mixture (2.7 parts). The product obtained is a thick slurry of the copolymer in the solvent mixture. Mineral oil (141 parts) is added to the slurry while the solvent mixture is distilled off at 150°C and then at 150°C/267 mbar (200 mm Hg). To 209 parts of the stripped mineral oil copolymer slurry (reduced specific viscosity of the copolymer: 0.72) are added toluene (25.2 parts), n-butyl alcohol (4.8 parts), a commercial alcohol consisting essentially of primary alcohols having 12 to 18 carbon atoms (56.6 parts) and a commercial alcohol consisting of primary alcohols having 8 to 10 carbon atoms (10 parts), and the resulting mixture is added with 96% sulfuric acid (2.3 parts). The mixture is then stirred for 20 hours. at 150-160ºC, after which water is distilled off. An additional amount of sulfuric acid (0.18 parts) is added together with an additional amount of n-butyl alcohol (3 parts) and the esterification is continued until 95% of the carboxyl groups of the polymer have been esterified. Aminopropylmorpholine (3.71 parts; 10% in excess of the stoichiometric amount required to neutralize the remaining free carboxyl groups) is then added to the esterified copolymer and the resulting mixture is heated to 150-160ºC/13 mbar (10 mm Hg) to distill off toluene and any other volatile components. The stripped product is mixed with an additional amount of mineral oil (12 parts) and filtered. The filtrate is a mineral oil solution of the nitrogen-containing mixed ester with a nitrogen content of 0.16-0.17%.

Example (B-2)

The procedure of Example (B-1) is repeated except that the esterification is carried out in two steps, the first step being the esterification of the styrene-maleic anhydride copolymer with the commercial alcohol having 8 to 18 carbon atoms and the second step being the further esterification of the copolymer with n-butyl alcohol.

Example (B-3)

The procedure of Example (B-1) is repeated except that the esterification is carried out by initially esterifying the styrene-maleic anhydride copolymer with the commercial alcohol having 8 to 18 carbon atoms until 70% of the carboxyl groups of the copolymer have been converted to the ester groups and then continuing the esterification with any unreacted commercial alcohols and n-butyl alcohol until 95% of the carbonyl groups of the copolymer have been converted to the ester groups.

Example (B-4)

The procedure of Example (B-1) is repeated except that the copolymer is prepared by polymerizing a solution consisting of styrene (416 parts), maleic anhydride (392 parts), benzene (2153 parts) and toluene (5025 parts) in the presence of benzoyl peroxide (1.2 parts) at 65-106°C. (The resulting copolymer has a reduced specific viscosity of 0.45.)

Example (B-5)

The procedure of Example (B-1) is repeated except that the styrene-maleic anhydride is obtained by polymerizing a mixture of styrene (416 parts), maleic anhydride (392 parts), benzene (6101 parts) and toluene (2310 parts) in the presence of benzoyl peroxide (1.2 parts) at 78-92°C. (The resulting copolymer has a reduced specific viscosity of 0.91.)

Example (B-6)

The procedure of Example (B-1) is repeated except that the styrene-maleic anhydride is prepared by the following procedure: Maleic anhydride (392 parts) is dissolved in benzene (6870 parts). To this mixture is added styrene (416 parts) at 76°C, followed by the addition of benzoyl peroxide (1.2 parts). The polymerization mixture is maintained at 80-82°C for about 5 hours. (The resulting copolymer has a reduced specific viscosity of 1.24.)

Example (B-7)

The procedure of Example (B-1) is repeated except that acetone (1340 parts) is used instead of benzene as the polymerization solvent and that azobisisobutyronitrile (0.3 parts) is used instead of benzoyl peroxide as the polymerization catalyst.

Example (B-8)

A copolymer (0.86 carboxyl equivalents) of styrene and maleic anhydride (prepared from an equimolar mixture of styrene and maleic anhydride and having a reduced specific viscosity of 0.69) is mixed with mineral oil to form a slurry and then esterified with a commercially available alcohol mixture (0.77 moles; comprising primary alcohols having 8 to 18 carbon atoms) at 150-160°C in the presence of a catalytic amount of sulfuric acid until about 70% of the carboxyl groups have been converted to ester groups. The partially esterified copolymer is then further esterified with an n-butyl alcohol (0.31 moles) until 95% of the carboxyl groups of the copolymer have been converted to the mixed ester groups. The esterified copolymer is then treated with aminopropylmorpholine (slight excess to the stoichiometric amount to neutralize the free carboxyl groups of the copolymer) at 150-160ºC until the product obtained in reacts essentially neutrally (acid number of 1 against phenolphthalein indicator). The product obtained is mixed with mineral oil to form an oil solution containing 34% of the polymeric product.

Examples (B-1) to (B-8) are prepared using mineral oil as a diluent. All or part of the mineral oil may be replaced by the triglyceride oil (A). The preferred triglyceride oil is high oleic sunflower oil.

Example (B-9)

A 12 liter four-necked flask is charged with 3621 parts of the copolymer of Example (B-8) in the form of a toluene slurry. The toluene content is about 76%. With stirring, 933 parts (4.3 equivalents) of Alfol 1218 alcohol and 1370 parts of xylene are added. The contents are heated and toluene is removed by distillation. Additional xylene is added in proportions of 500, 500, 300 and 300 parts while the removal of toluene is continued, which should result in replacement of the lower boiling toluene with the higher boiling xylene. Removal of the solvent is stopped when a temperature of 140°C is reached. The flask is then fitted with an additional funnel and the reaction mixture is refluxed. At 140ºC, 23.6 parts (0.17 equivalents) of methanesulfonic acid in 432 parts (3 equivalents) of Alfol 810 alcohol are added over a period of about 20 minutes. The contents are stirred at reflux overnight while collecting water in a Dean-Stark trap. Then 185 parts (2.5 equivalents) of n-butanol containing 3.0 parts (0.02 equivalents) of methanesulfonic acid are added. This addition is carried out over a period of 60 minutes. The contents are refluxed for 8 hours and then an additional 60 parts (0.8 equivalents) of n-butanol are added and the contents are refluxed overnight. At 142ºC, 49.5 parts (0.34 equivalents) of aminopropylmorpholine are added over a period of 60 minutes. After 2 hours under reflux, 13.6 parts (equivalents) of 50% aqueous sodium hydroxide solution are added over 60 minutes and after stirring for a further 60 minutes, 17 parts of an alkylated phenol are added.

A 1 liter flask is charged with 495 parts of the above esterified product. The contents are heated to 140ºC and 337 parts of Sunyl® 80 are added. The solvent is removed at 155ºC by nitrogen blowing at 28.2 l/h (1 cfh). The final blowing conditions are 155ºC and 27 mbar (20 mm Hg). At 100ºC the contents are Filtered using diatomaceous earth. The filtrate is a solution of the nitrogen-containing mixed ester with a nitrogen content of 0.14% in vegetable oil.

In Examples (B-10) and (B-11), a copolymerizable monomer is used as part of the carboxyl group-containing copolymer.

Example (B-10)

1 mole each of maleic anhydride and styrene and 0.05 mole of methyl methacrylate are polymerized in toluene in the presence of benzoyl peroxide (1.5 parts) at 75-95°C. The resulting copolymer has a reduced specific viscosity of 0.13 and is a 12% slurry in toluene. A 2 liter four-necked flask is charged with 868 parts (1 equivalent) of the polymer together with 68 parts (0.25 equivalent) of oleyl alcohol, 55 parts (0.25 equivalent) of Neodol 45, 55 parts (0.25 equivalent) of Alfol 1218 and 36 parts (0.25 equivalent) of Alfol 8-10. The contents are heated to 115ºC and 2 parts (0.02 mol) of methanesulfonic acid are added. After a reaction time of 2 hours, toluene is distilled off. 15 parts (0.20 equivalents) of n-butanol are added dropwise over 5 hours until a neutralization number of 18.7 against phenolphthalein (which corresponds to an esterification of 89%) is reached. The neutralization number and the degree of esterification are 14.0 and 92.5% respectively. Then 1.6 parts (0.02 mol) of 50% aqueous sodium hydroxide solution are added to neutralize the catalyst. Then 5.5 parts (0.038 equivalents) of aminopropylmorpholine and 400 parts of Sunyl® 80 are added. The contents are stripped at 100ºC to 20 mbar (15 mm Hg) and filtered using a diatomaceous earth filter aid. The filtrate is the product containing 0.18% nitrogen and 54.9% Sunyl® 80.

The following example is similar to Example (B-10), but uses different alcohols and different amounts in a different order of addition.

Example (B-11)

A 2-liter four-necked flask is charged with 868 parts (1 equivalent) of the polymer of Example (B-10), 9.25 parts (0.125 equivalent) of isobutyl alcohol, 33.8 parts (0.125 equivalent) of oleyl alcohol, 11 parts (0.125 equivalent) each of 2-methyl-1-butanol, 3-methyl-1-butanol and 1-pentanol, 23.4 parts (0.125 equivalent) of hexyl alcohol and 16.25 parts (0.125 equivalent) each of 1-octanol and 2-octanol. At 110ºC, 2 parts (0.02 mole) of methanesulfonic acid are added. After 1 hour, toluene is distilled off and when the distillation is complete, the neutralization number or degree of esterification is 62.5 or 70%. At 140ºC, 31.2 parts (0.43 equivalents) of n-butanol are added dropwise over 28 hours and the neutralization number or degree of esterification is 36.0 or 79.3%. At 120ºC, 0.3 parts (0.03 mol) of methanesulfonic acid are added, followed by 20.4 parts (0.20 equivalents) of hexyl alcohol. After esterification, the neutralization number or degree of esterification is 10.5 or 95%. Then 1.9 parts (0.023 mole) of 50% sodium hydroxide solution are added, followed by 5.9 parts (0.04 equivalents) of aminopropylmorpholine and 400 parts of Sunyl® 80. The contents are filtered and the product contains 0.18% nitrogen.

Acrylate polymers

In another aspect, component (B) may comprise at least one hydrocarbon-soluble acrylate polymer of the general formula

in which the radical R⁵ is a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, the radical R⁵ is a mixture of alkyl, cycloalkyl or aromatic groups having 4 to 24 carbon atoms and x is an integer which ensures a weight average molecular weight (Mw) of the acrylate polymer of 5000 to 1 million.

Preferably, R5 is a methyl or ethyl group, and especially a methyl group. R6 is primarily a mixture of alkyl groups having from 4 to 18 carbon atoms. In one embodiment, the weight average molecular weight of the acrylate polymer is from 100,000 to 1 million, and in other embodiments, the molecular weight of the polymer is from 100,000 to 700,000 and from 300,000 to 700,000.

Specific examples of these alkyl groups R⁶ which may be contained in the polymers of the present invention include, for example, n-butyl, octyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl. The mixture of alkyl groups can be varied as long as the resulting polymer is hydrocarbon-soluble.

The following non-limiting examples illustrate the preparation of the acrylate polymers of the present invention. All parts and percentages are by weight unless otherwise indicated.

Example (B-12)

A 2 liter four-necked flask is charged with 50.8 parts (0.20 mole) of lauryl methacrylate, 44.4 parts (0.20 mole) of isobornyl methacrylate, 38.4 parts (0.20 mole) of 2-phenoxyethyl acrylate, 37.6 parts (0.20 mole) of 2-ethylhexyl acrylate, 45.2 parts (0.20 mole) of isodecyl methacrylate and 500 parts of toluene. At 100ºC, 1 part of Vazo® 67 (2,2'-azobis-(2-methylbutyronitrile)) in 20 parts of toluene is added over 7 hours. The reaction mixture is held at 100°C for 16 hours, after which the temperature is raised to 120°C to remove toluene and 216 parts of Sunyl® 80 are added. Volatiles are removed by distillation under reduced pressure at 27 mbar (20 mm Hg) at 140°C. The contents are filtered to give the desired product.

Example (B-13)

A 2-liter four-necked flask is charged with 38.1 parts (0.15 mole) of lauryl methacrylate, 48.6 parts (0.15 mole) of stearyl acrylate, 28.2 parts (0.15 mole) of 2-ethylhexyl methacrylate, 25.5 parts (0.15 mole) of tetrahydrofurfuryl methacrylate, 33.9 parts (0.15 mole) of isodecyl methacrylate and 500 parts of toluene. At 100ºC, 1 part of Vazo® 67 in 20 parts of toluene is added dropwise over 6 hours. After the addition is complete, the reaction mixture is kept at 100ºC for 15.5 hours, toluene is distilled off and 174 parts of Sunyl® 80 are added. The contents are stripped at 140ºC at 27 mbar (20 mm Hg) and filtered to give the desired product.

An example of a commercially available methacrylate ester polymer useful in the present invention is sold under the trademark "Acryloid 702" by Rohm and Haas, wherein the R5 radical is predominantly a mixture of n-butyl, tridecyl and octadecyl groups. The weight average molecular weight (Mw) of the polymer is about 404,000 and the number average molecular weight (Mn) is about 118,000. Other commercially available methacrylate polymers useful in the present invention are sold under the trademark "Acryloid 954" by Rahm and Haas, wherein the R5 radical is predominantly a mixture of n-butyl, decyl, tridecyl, octadecyl and tetradecyl groups. The weight average molecular weight of Acryloid 954 is about 440,000 and the number average molecular weight weight is about 111,000. Each of these commercial methacrylate polymers is sold in the form of a concentrate containing about 40% by weight of the polymer in a light colored mineral lubricating base oil. When the polymer is designated by the trademark, the amount of material added is an amount of the commercial acryloid material including the oil.

Other commercially available polymethacrylates are from Rohm and Haas as Acryloid 1253, Acryloid 1265, Acryloid 1263, Acryloid 1267, from Rohm GmbH as Viskoplex 0-410, Viskoplex 10-930, Viskoplex 5029, from Societe Francaise D'Organo-Synthese as Garbacryl T-84, Garbacryl T- 78S, from Texaco as TLA 233, TLA 5010 and TC 10124. Some of these polymethacrylates may be PMA/OCP (olefin copolymer) type polymers.

Nitrogen-containing polyacrylates

Component (B) may also be a nitrogen-containing polyacrylate obtained by reacting an acrylate ester of the general formula

in which R9 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and R10 is an alkyl, cycloalkyl or an aromatic group having 4 to 24 carbon atoms, with a nitrogen-containing compound. 0.001 to 1.0 mole of the nitrogen-containing compound is used per mole of the acrylate ester. The reaction is carried out at a temperature of 50°C to 250°C. Non-limiting examples of nitrogen-containing compounds are 4-vinylpyridine, 2-vinylpyridine, 2-N-morpholinoethyl acrylate, N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl methacrylate.

The following non-limiting example illustrates the preparation of the nitrogen-containing polymethacrylate. All parts and percentages are by weight, unless otherwise indicated.

Example (B-14)

A 2-liter four-necked flask is charged with 50.8 parts (0.2 mol) lauryl methacrylate, 44.4 parts (0.20 mol) isobornyl methacrylate, 38.4 parts (0.20 mol) 2-phenoxyethyl acrylate, 37.6 parts (0.20 mol) 2-ethylhexyl acrylate, 45.2 parts (0.20 mole) isodecyl methacrylate, 21 parts (0.20 mole) 4-vinylpyridine and 500 parts toluene. At 100ºC, 1 part Vazo 67 in 20 parts toluene is added dropwise over 8 hours. After maintaining the temperature at 100ºC for an additional 20 hours, an additional 0.5 parts Vazo 67 in 10 parts toluene is added over 3 hours. The toluene is then removed by distillation and 235 parts Sunyl® 80 are added and the contents are stripped under reduced pressure to 33 mbar (25 mm Hg) at 140ºC. The contents are filtered to give a product containing 0.71% nitrogen.

Some companies that produce nitrogen-containing polyacrylates are Rohm and Haas, Rohm GmbH, Texaco, Albright & Wilson, Societe Francaise D'Organo-Synthese (SFOS).

Methylene-linked aromatic compounds

Another PPD suitable in this invention is a mixture of compounds of the general formula

Ar-(R7 )-[-Ar'(R8 )]nAr"

in which Ar, Ar' and Ar" are independently an aromatic group and each aromatic group is substituted with 0 to 3 substituents (the preferred aromatic precursor is naphthalene), R⁷ and R⁸ are independently straight chain or branched chain alkylenes having 1 to 100 carbon atoms, and n is 0 to 1000.

This PPD is characterized by the presence of compounds over a wide range of molecular weights. The molecular weight of compounds in the composition of the invention could vary from that of a simple, unsubstituted benzene to that of a polymer containing 1000 monomers of trisubstituted naphthalenes linked by alkylenes of 100 carbon atoms, with the substituents of the naphthalene containing 1 to 50 carbon atoms.

The substituents for the aromatic groups are obtained from olefins and/or chlorinated hydrocarbons.

The suitable olefins include 1-octene, 1-decene and alpha-olefins having chain lengths of C₁₂, C₁₄, C₁₆₋₁₈, C₁₅₋₂₀, C₁₅₋₂₀ and C₁₆₋₂₈. More preferably, the process of the invention with olefins which are mixtures of the above olefins. A suitable example would be the C₁₅₋₂₀ cracked waxy olefins or a mixture of 1-octene and C₁₆₋₁₈ alpha-olefin.

The chlorinated hydrocarbons could contain 1-50 carbon atoms and 2 to 84 weight percent chlorine. Preferred chlorinated hydrocarbons are obtained by chlorinating crude paraffin waxes or paraffin waxes of C18-30 chain length to a chlorine content of 5-50 weight percent. A particularly preferred chlorinated hydrocarbon contains about 24 carbon atoms and about 2.5 chlorine atoms per 24 carbon atoms.

Although Ar, Ar' and Ar" may be any aromatic group having 1 to 3 aromatic rings, Ar, Ar' and Ar" are preferably the same. In addition, Ar, Ar' and Ar" are preferably fused benzene rings, i.e., when 2 or 3 benzene rings are present, the fused rings each have 2 carbon atoms in common. In particular, Ar, Ar' and Ar" are all derived from naphthalene.

Aromatics that can be precursors of Ar, Ar' and Ar" include benzene, biphenyl, diphenylmethane, triphenylmethane, aniline, diphenylamine, diphenyl ether, phenol, naphthalene, anthracene and phenanthrene. Naphthalene is particularly preferred.

Although the aromatic radicals of the above general formula may contain 0 to 3 substituents, the compositions are intended to contain compounds having 1 or 2 substituents and will preferably contain compounds having 2 substituents. The substituents may be derived from any olefin (preferably an alpha-olefin having 8 to 30 carbon atoms) or from a chlorinated hydrocarbon having 8 to 50 carbon atoms (preferably a chlorinated hydrocarbon derived from a hydrocarbon wax having 22 to 26 carbon atoms). In addition to or instead of forming the substituents, the olefin and/or chlorinated hydrocarbon may form the alkylene linking group (the radicals R7 and R8) of the general formula. The compositions of the invention may include compounds in which each of the naphthalene groups is substituted with an alkyl group having 16 to 18 carbon atoms and a group derived from a chlorinated hydrocarbon having about 24 carbon atoms and about 2.5 chlorine atoms per 24 carbon atoms.

The desired material is a mixture of products containing alkylated naphthalenes, coupled and bridged naphthalenes, oligomers and dehydrohalogenated waxes. The Mw distribution of the final product is a more appropriate characterization of the final product.

A suitable Mw range is 300-2000. A more suitable Mw range is 500 to 10000. A preferred distribution is 400 to 112000. The most suitable distribution is 271 to 300000.

A methylene-linked aromatic PPD compound can be prepared according to the following general procedure:

(a) providing aromatic compounds having 1 to 3 aromatic rings, wherein the compounds are substituted with 0 to 3 substituents and wherein the compounds are precursors for aromatic groups Ar, Ar' and Ar", in a reaction vessel;

(b) adding a Friedel-Crafts or Lewis acid catalyst to the reaction vessel;

(c) adding a chlorinated hydrocarbon to the reaction vessel;

(d) adding an olefin to the reaction vessel and

(e) adding CH2Cl2 to the reaction vessel, wherein step (e) is carried out before or simultaneously with at least one of steps (a)-(d).

As noted above, the aromatic compounds constituting the Ar, Ar' and Ar" groups of the compound represented by the general formula are preferably naphthalene. When the aromatic compound is substituted, it is substituted with an alkyl or alkenyl group, each of which may be chlorine-substituted, branched chain or straight chain. Accordingly, according to one embodiment of the process of the invention, naphthalene is mixed with methylene chloride in a reaction flask. At this point, the methylene chloride serves as a solvent. A Friedel-Crafts or Lewis acid catalyst is then added to the mixture. The catalyst is preferably AlCl₃. After the addition of the catalyst, a chlorinated hydrocarbon (particularly a chlorinated hydrocarbon having 22 to 26 carbon atoms) is added to the reaction flask and a reaction takes place between the naphthalene and the chlorinated hydrocarbon wax such that the Naphthalene is substituted with an alkyl group derived from the chlorinated hydrocarbon wax. Moreover, the connection of naphthalene compounds will take place via methylene groups as shown in the general formula (R⁷ or R⁸ is the group CH₂).

The mixture is then cooled, preferably to a temperature in the range of 0 to 5°C. While cooling of the vessel continues, an olefin (preferably an alpha-olefin having 8 to 30 carbon atoms) is slowly added so that the temperature remains in the range of 0 to 5°C. Alkylation of the naphthalene compounds occurs so that the naphthalenes are substituted with an alkyl group derived from the olefin. The catalyst is decomposed and neutralized with a base such as lime, after which stirring is continued while the temperature is increased initially to 60°C and then to 120°C to remove the volatile components of the reaction mixture. The mixture is filtered and the desired product is isolated.

Chlorinated hydrocarbons which can form a substituent on one or more of the aromatic groups can contain from 1 to 50 carbon atoms. When a chlorinated hydrocarbon having 50 carbon atoms forms a substituent and is bonded to another substituent having 50 carbon atoms on another aromatic radical, the aromatic radicals will be connected by an alkylene group having 100 carbon atoms, i.e., (R⁷) or (R⁸) contains about 100 carbon atoms. However, the aromatic radicals Ar can be connected by a single CH₂ group, i.e., an alkylene group having a single carbon atom, where (R⁷) or (R⁸) is the group CH₂.

The general procedure for preparing this PPD can be carried out in a wide range of component ratios. To describe the ratio of components added in steps (a), (b), (c), (d) and (e), the components are designated by the letters (a'), (b'), (c'), (d') and (e'), respectively. It is only necessary that (e') be present in a sufficient amount so that at least some bonding between components (a') takes place through methylene and/or that (b'), (c') and (d') be present in sufficient amounts so that at least some substitution of (a') by (c') and (d') catalyzed by (b') takes place. Components (a), (b'), (c'), (d') and (e') may be present in weight ratios of (a') : (b') : (c') : (d') : (e') in ranges of approximately (1 : 0.01-1) : (0.5-6) : (0.5- 22) : (1-40) and in particular in the ratio (1) : (0.2) : (3) : (11) : (20); all ratios are given in parts by weight.

The process can be carried out over a wide range of temperatures above the freezing point and up to the boiling points of the reaction mixture present at any point in steps (a)-(e). The boiling point of (e'), ie methylene chloride, is about 40°C, but the maximum reaction temperature may vary due to the presence of other reactants higher or lower than 40ºC at atmospheric pressure. The process can be carried out at a pressure lower or higher than atmospheric pressure.

Example B-10

Naphthalene is mixed with 7 parts CH2Cl2 and 0.2 parts AlCl3. A chlorinated hydrocarbon (2.7 parts) is slowly added to the reaction mixture at 15°C. The reaction mixture is kept at room temperature for 5 hours or until the release of HCl is complete. The mixture is then cooled to about 5°C and 7.3 parts of an alpha-olefin mixture are added over 2 hours while maintaining the temperature of the reaction mixture between 0 and 10°C.

The catalyst is decomposed by careful addition of 0.8 parts of 50% aqueous NaOH solution. The aqueous layer is separated and the organic layer is purged with nitrogen and heated to 140ºC/4 mbar (3 mm Hg) to remove the volatiles. The residue is filtered to give 97% of the theoretical yield weight of the product.

(C) The additive

In addition to components (A) and (B), the composition of the invention also contains (C)(4) an antioxidant additive. The composition may also contain (C)(1)-(3). The performance can be improved by these additives in the areas of antiwear, oxidation and inhibition, rust/corrosion inhibition, metal passivation, extreme pressure, friction reduction, viscosity modification, antifoaming, emulsification, demulsification, lubricity, dispersibility and detergency.

(C) (1) is a compound of the general formula R¹¹A, in which the radical R¹¹ is an aliphatic group having 6 to 24 carbon atoms and the radical A is -COOH and/or -OH or -NO₃;

(C)(2) is a Schiff base;

(C)(3) is a carboxyl dispersant composition; and

(C)(4) is an antioxidant comprising (a) and (b) and (c) as described below.

(C)(1) The compound R¹¹A

The compound R¹¹A is either a carboxylic acid or an alcohol or a mixture thereof or an organic nitrate. When the radical A is -COOH, the radical R¹¹ preferably contains 12 to 24 carbon atoms and especially 14 to 20 carbon atoms. The most preferred carboxylic acid is oleic acid.

When the radical A is -OH, the radical R¹¹ preferably contains 6 to 12 carbon atoms. Preferred alcohols are the isomeric octyl alcohols, especially isooctyl alcohol.

When the radical A is -NO₃, the radical R¹¹ preferably contains 6 to 12 carbon atoms. Preferred nitrates are the isomeric octyl nitrates, especially 2-ethylhexyl nitrate.

(C)(2) The Schiff Base

A Schiff base that can be used in this invention has the general formula

in which the radical R¹² is an aliphatic group having 1 to 8 carbon atoms and the radical R¹³ is an aliphatic group having 1 to 18 carbon atoms or an aromatic or a substituted aromatic group having 6 to 18 carbon atoms and n has the value 0 or 1.

The Schiffache base is formed by the reaction of a primary amine with an aldehyde. The amine can be a primary monoamine, so that n has the value 0, or a primary vicinal diamine, so that n has the value 1.

The following Table I concerns the preparation of Schiff bases. The amine is added dropwise to the aldehyde or vice versa and the reaction mixture is heated until the desired amount of water is obtained. TABLE I

(C)(3) The carboxyl dispersant composition

The carboxyl dispersant composition has in its molecular structure (1) at least one polar group selected from acyl, acyloxy or hydrocarbyl imidoyl groups and (ii) at least one group in which a nitrogen or oxygen atom is directly bonded to group (i), and wherein the nitrogen or oxygen atom is also bonded to a hydrocarbyl group. The structures of the polar groups (i), defined according to IUPAC, are as follows (the radical R27 represents a hydrocarbon or similar group): Acyl: Acyloxy: Hydrocarbalimidoyl:

Group (ii) is preferably at least one group in which a nitrogen or oxygen atom is directly bonded to the polar group, wherein the nitrogen or oxygen atom is also bonded to a hydrocarbon group or a substituted hydrocarbon group, in particular an amino, alkylamino, polyalkyleneamino, hydroxy or alkyleneoxy substituted hydrocarbon group. In relation to group (ii), the dispersants are conveniently referred to as "nitrogen-bridged dispersants" and "oxygen-bridged dispersants", wherein the atom directly bonded to the polar group (i) is a nitrogen or oxygen atom, respectively.

In general, the carboxyl dispersants can be prepared by reacting a hydrocarbon-substituted succinic acid-producing compound (sometimes referred to herein as the "succinic acylating agent") with at least about one-half equivalent per equivalent of the acid-producing compound, an organic hydroxy compound or an amine having at least one hydrogen atom bonded to a nitrogen group, or a mixture of the hydroxy compound and the amine. The carboxyl dispersants (C-4) thus obtained are usually complex mixtures whose exact composition is difficult to determine. The nitrogen-containing carboxyl dispersants are sometimes referred to herein as "acylated amines". The compositions obtained by reacting the acylating agent with alcohols are sometimes referred to herein as "carboxylic ester" dispersants. The carboxyl dispersants (C-3) are either oil soluble or they are soluble in the oil-containing lubricating fluids and functional fluids of this invention.

The soluble nitrogen-containing carboxyl dispersants useful as component (C-3) in the compositions of the invention are known and have been described in many US patents, including

3,172,892 3,341,542 3,630,904

3,219,666 3,444,170 3,787,374

3,272,746 3,454,607 4,234,435

3,316,177 3,541,012

The carboxylic acid ester dispersants suitable as (C-3) have also been described in the prior art. Examples of patents describing such dispersants are US Pat. Nos. 3,381,022, 3,522,179, 3,542,678, 3,957,855 and 4,034,038. Carboxylic dispersants prepared by reacting acylating agents with alcohols and amines or amino alcohols are described, for example, in US Pat. Nos. 3,576,743 and 3,632,511.

In general, a convenient way to prepare the nitrogen-containing carboxyl dispersants (C-3) involves reacting a hydrocarbon-substituted succinic acid-producing compound ("carboxylic acid acylating agent") with an amine containing at least one hydrogen atom bonded to a nitrogen atom (i.e., H-N<). The hydrocarbon-substituted succinic acid-producing compounds include the succinic acids, anhydrides, halides and esters. The number of carbon atoms in the hydrocarbon substituent of the succinic acid-producing compound can vary over a wide range, provided that the nitrogen-containing composition (C-3) is soluble in the lubricant compositions of the present invention. Thus, the hydrocarbon substituent will generally contain an average of at least 12 aliphatic carbon atoms, and preferably an average of at least 50 aliphatic carbon atoms. In addition to oil solubility considerations, the lower limit of the average number of carbon atoms in the substituent is also based on the effectiveness of such compounds in the lubricating oil compositions of the present invention. The hydrocarbyl substituent of the succinic acid compound may contain polar groups as noted above, provided that the polar groups are not present in an amount sufficient to significantly alter the hydrocarbon character of the substituent.

The sources of the essentially hydrocarbon substituents include basically the essentially saturated high molecular weight petroleum fractions and the essentially saturated high molecular weight olefin polymers, in particular polymers of monoolefins having 2 to 30 carbon atoms. The particularly suitable polymers are the polymers of 1-monoolefins such as ethylene, propene, 1-butene, isobutene, 1-hexene, 1-octene, 2-methyl-1-heptene, 3-cyclohexyl-1-butene and 2-methyl-5-propyl-1-hexene. Polymers of medium olefins, i.e. olefins in which the olefinic bond is not in the terminal position, are also suitable. Examples of these are 2-butene, 2-pentene and 4-octene.

Also suitable are the copolymers of, for example, the olefins illustrated above with other copolymerizable olefinic substances such as aromatic olefins, cyclic olefins and polyolefins. Such copolymers include, for example, the copolymers prepared by polymerizing the following olefin pairs: isobutene with styrene; isobutene with butadiene; propene with isopropene; ethylene with piperylene; isobutene with chloroprene; isobutene with p-methylstyrene; 1-hexene with 1,3-hexadiene; 1-octene with 1-hexene; 1-heptene with 1-pentene; 3-methyl-1-butene with 1-octene, 3,3-dimethyl-1-pentene with 1-hexene; isobutene with styrene and piperylene.

The relative proportions of the monoolefins with respect to the other monomers in the copolymers affect the stability and oil solubility of the final product derived from such copolymers. Therefore, for reasons of oil solubility and stability, the copolymers contemplated for use in this invention should be substantially aliphatic and substantially saturated, i.e., they should contain at least about 80%, preferably at least 95%, on a weight basis, units derived from the aliphatic monoolefins and contain no more than about 5% olefinic linkages based on the total number of carbon-carbon covalent bonds. In most cases, the percentage of olefinic linkages should be less than 2% of the total number of carbon-carbon covalent bonds.

Specific examples of such copolymers include copolymers of 95 wt.% isobutene with 5% styrene; a terpolymer of 98% isobutene with 1% piperylene and 1% chloroprene; a terpolymer of 95% isobutene with 2% 1-butene and 3% 1-hexene; a terpolymer of 80% isobutene with 20% 1-pentene and 20% 1-octene; a copolymer of 80% 1-hexene and 20% 1-heptene; a terpolymer of 90% isobutene with 2% cyclohexene and 8% propene, and a copolymer of 80% ethylene and 20% propene.

Another source of the essentially hydrocarbon group includes saturated aliphatic hydrocarbons such as highly refined high molecular weight white oils or synthetic alkanes such as those obtained by hydrogenation of high molecular weight olefin polymers as illustrated above or high molecular weight olefinic substances.

The use of olefin polymers having molecular weights (Mn) of 700 to 10,000 is preferred. Higher molecular weight olefin polymers having molecular weights (Mn) of 10,000 to 100,000 or more also impart viscosity index improving properties to the final products of the invention. The use of such high molecular weight olefin polymers is often desirable. The substituent is preferably derived from a polyolefin characterized by an Mn of 700 to 10,000 and an Mw/Mn of 1.0 to 4.0.

In preparing the substituted succinic acylating agents of this invention, one or more of the polyalkenes described above are reacted with one or more acid reactants selected from the group consisting of maleic or fumaric acid reactants and acids or anhydrides. Usually, the maleic or Fumaric acid reactants may be maleic acid, fumaric acid, maleic anhydride, or mixtures of two or more thereof. The maleic acid reactants are usually preferred over the fumaric acid reactants because the former are more readily available and generally can be more easily reacted with the polyalkenes (or derivatives thereof) to produce the substituted succinic acid-producing compounds useful in the present invention. The most preferred reactants are maleic acid, maleic anhydride, and mixtures thereof. Due to availability and ease of reaction, maleic anhydride will usually be preferred.

For convenience and brevity, the term "maleic reactant" is often used hereinafter. The term is intended to be a collective name for acidic reactants selected from maleic and fumaric reactants, including a mixture of such reactants. The term "succinic acylating agent" is used herein to refer to the substituted succinic acid-producing compounds.

A process for preparing the substituted succinic acylating agents useful in this invention is illustrated in part in U.S. Patent 3,219,666. This process is conveniently referred to as the "two-step process." It involves first chlorinating the polyalkene until it contains, on average, at least about one chlorine atom per unit molecular weight of the polyalkene. (For the purposes of this invention, the molecular weight of the polyalkene is the weight corresponding to the Mn value.) Chlorination involves merely contacting the polyalkene with chlorine gas until the desired amount of chlorine has been incorporated into the chlorinated polyalkene. Chlorination is generally carried out at a temperature of from 75°C to 125°C. If a diluent is used in the chlorination process, it should be stable to the chlorination. Examples of suitable diluents are poly- and perchlorinated and/or fluorinated alkanes and benzenes.

For the purposes of this invention, the second step of the two-step chlorination process is the reaction of the chlorinated polyalkene with the maleic acid reactant at a temperature usually in the range of 100°C to 200°C. The molar ratio of chlorinated polyalkene to maleic acid reactant is usually 1:1. (For the purposes of this invention, 1 mole of the chlorinated polyalkene is the weight of the chlorinated polyalkene equal to the Mn of the unchlorinated polyalkene.) However, a stoichiometric excess of the maleic acid reactant may be used, e.g., a molar ratio of 1:2. If an average of more than about 1 chlorine atom per molecule of the polyalkene is introduced during the chlorination step, then more than 1 mole of the maleic acid reactant per molecule of the chlorinated polyalkene. Because of this, it is more convenient to express the ratio of chlorinated polyalkene to the maleic reactant in terms of equivalents. (For the purposes of this invention, the equivalent weight of chlorinated polyalkene is the weight equal to the Mn divided by the average number of chlorine atoms per molecule of the chlorinated polyalkene, while the equivalent weight of a maleic reactant is its molecular weight.) Therefore, the ratio of chlorinated polyalkene to the maleic reactant will normally be such as to provide from about 1 equivalent of the maleic reactant per mole of the chlorinated polyalkene to about 1 equivalent of the maleic reactant per equivalent of the chlorinated polyalkene, it normally being desirable to provide an excess of maleic reactant, for example, a 5 to 25 weight percent excess. Unreacted excess maleic acid reactant can be stripped from the reaction product, usually under reduced pressure, or reacted during a further step of the process, as explained below.

The resulting polyalkene-substituted succinic acylating agent is optionally chlorinated again if the desired number of succinic groups is not present in the product. If any excess maleic reactant from the second step is present at the time of this subsequent chlorination, this excess will react when additional chlorine is introduced during the subsequent chlorination. Otherwise, additional maleic reactant is introduced during and/or after the additional chlorination step. This technique can be repeated until the total number of succinic groups per equivalent weight of substituent groups reaches the desired level.

Another method for preparing substituted succinic acylating agents useful in this invention utilizes a method described in U.S. Patent No. 3,912,764 and British Patent No. 1,440,219.

According to this process, the polyalkene and the maleic acid reactant are first reacted by heating them together in a "direct alkylation" process. When the direct alkylation step is completed, chlorine is introduced into the reaction mixture to accelerate the reaction of the remaining unreacted maleic acid reactants. According to these patents, from 0.3 to 2 or more moles of the maleic anhydride per mole of the olefin polymer, i.e., polyalkylene, are used in this reaction. The direct alkylation step is carried out at temperatures of 180-250°C. During this step of chlorine introduction, a temperature of 160-225°C is used. In the Using this process to prepare the substituted succinic acylating agents of this invention, it would be necessary to employ sufficient maleic reactant and chlorine to introduce at least 1.3 succinic groups into the final product per equivalent weight of polyalkene.

Another method for preparing the substituted succinic acylating agents of this invention is the so-called "one-step process." This process is described in U.S. Patents 3,215,707 and 3,231,587.

Basically, the one step process involves preparing a mixture of the polyalkene and the maleic reactant containing the necessary amounts of these two compounds to provide the desired substituted succinic acylating agents of this invention. That is, there must be at least 1 mole of maleic reactant per mole of polyalkene so that there can be at least one succinic group per equivalent weight of substituent groups. Chlorine is then introduced into the mixture, usually by passing chlorine gas through the mixture with stirring while maintaining a temperature of at least about 140°C.

A variation of this process involves the addition of additional maleic reactant during or after the chlorine feed, but, for reasons explained in U.S. Patents 3,215,707 and 3,231,587, this variation is not as preferred as initially mixing all of the polyalkene and all of the maleic reactant prior to the introduction of the chlorine.

If the polyalkene is sufficiently fluid at 140°C and above, there is usually no need to use an additional substantially inert, normally liquid solvent/diluent in the one-step process. However, if a solvent/diluent is used, it is preferably a chlorination-resistant solvent/diluent, as set forth above. Again, poly- and perchlorinated and/or -fluorinated alkanes, cycloalkanes and benzenes can be used for this purpose.

During the one-step process, chlorine can be added continuously or intermittently. The rate of addition is not critical, although to maximize chlorine utilization, the rate of addition should be approximately equal to the rate of chlorine consumption during the course of the reaction. If the rate of addition of chlorine exceeds the rate of chlorine consumption, chlorine will escape from the reaction mixture. It is often advantageous to use a closed system, including a pressure, greater than atmospheric pressure to prevent chlorine loss and thus maximize the use of chlorine.

The minimum temperature at which the reaction will occur at a reasonable rate in the one-step process is 140°C. Therefore, the minimum temperature at which the process is normally carried out is in the vicinity of 140°C. The preferred temperature range is usually between 160 and 220°C. Higher temperatures such as 250°C or even higher temperatures may be used, but usually with little benefit. In fact, temperatures above 220°C are often detrimental to the preparation of the individual acylated succinic acid compositions of the invention because they tend to "crack" the polyalkenes (i.e., reduce their molecular weight by thermal decomposition) and/or decompose the maleic acid reactant. For this reason, maximum temperatures of 200-210°C are normally not exceeded. The upper limit of the suitable temperature in the one-step process is determined primarily by the decomposition point of the components in the reaction mixture, including the reactants and the desired products. The decomposition point is the temperature at which sufficient decomposition of any reactant or product occurs to affect the production of the desired products.

In the one-step process, the molar ratio of maleic reactants to chlorine is chosen so that at least about 1 mole of chlorine per mole of maleic reactant is incorporated into the product. In addition, for practical reasons, a slight excess, usually in the range of about 5% to about 30% by weight of chlorine, is used to compensate for any loss of chlorine from the reaction mixture. Larger amounts of excess chlorine can be used, but this does not appear to produce favorable results.

The molar ratio of polyalkene to maleic reactant is preferably selected so that at least about 1 mole of maleic reactant is present per mole of polyalkene. This is necessary for the presence of at least 1.0 succinic groups per equivalent weight of substituent group in the product. Preferably, however, an excess of maleic reactant is used. Therefore, 5 to 25% excess of maleic reactant will usually be used, relative to the amount necessary to ensure the desired number of succinic groups in the product.

The amines reacted with the succinic acid generating compounds to form the nitrogen-containing compositions (C-3) can be monoamines and polyamines.

The monoamines and polyamines must contain at least one H-N< group within their structure. They therefore have at least one primary (i.e. H₂N-) or secondary (i.e. H-N<) amino group. The amines can be aliphatic, cycloaliphatic, aromatic or heterocyclic, including aliphatic-substituted cycloaliphatic, aliphatic-substituted aromatic, aliphatic-substituted heterocyclic, cycloaliphatic-substituted aliphatic, cycloaliphatic-substituted aromatic, cycloaliphatic-substituted heterocyclic, aromatic-substituted aliphatic, aromatic-substituted cycloaliphatic, aromatic-substituted heterocyclic-substituted alicyclic and heterocyclic-substituted aromatic amines and can be saturated or unsaturated. The amines may also contain non-hydrocarbon substituents or groups so long as these groups do not significantly interfere with the reaction of the amines with the acylating agents of this invention. Such non-hydrocarbon substituents or groups include lower alkoxy, lower alkyl mercapto, nitro groups, interrupting groups such as -O- and -S- (e.g., in groups such as -CH₂CH₂-X- CH₂CH₂-, where X is -O- or -S-). In general, the amine of (C-3) can be represented by the general formula

R¹�sup4;R¹�sup5;NH

wherein R¹⁴ and R¹⁵ are each independently hydrogen or hydrocarbon, amino-substituted hydrocarbon, hydroxy-substituted hydrocarbon, alkoxy-substituted hydrocarbon, amino, carbamyl, thiocarbamyl, guanyl and acylimidoyl groups, with the proviso that only one of R¹⁴ and R¹⁵ can be hydrogen.

Except for the branched chain polyalkylenepolyamine, the polyoxyalkylenepolyamines, and the high molecular weight hydrocarbyl-substituted amines described in more detail below, the amines usually contain less than about 40 total carbon atoms and usually no more than about 20 total carbon atoms.

Aliphatic monoamines include monoaliphatic and dialiphatic substituted amines, where the aliphatic groups can be saturated or unsaturated and straight-chain or branched-chain. They are therefore primary or secondary aliphatic amines. Such amines include, for example, mono- and dialkyl-substituted amines, mono- and dialkenyl-substituted amines and amines having an N-alkenyl substituent and an N-alkyl substituent and the like. The total number of carbon atoms in these aliphatic monoamines will, as mentioned above, normally be about 40 and usually about 20. carbon atoms. Specific examples of such monoamines include ethylamine, diethylamine, n-butylamine, di-n-butylamine, allylamine, isobutylamine, cocoamine, stearylamine, laurylamine, methyllaurylamine, oleylamine, N-methyloctylamine, dodecylamine, octadecylamine. Examples of cycloaliphatic-substituted aliphatic amines, aromatic-substituted aliphatic amines and heterocyclic-substituted aliphatic amines include 2-(cyclohexyl)ethylamine, benzylamine, phenethylamine and 3-(furylpropyl)amine.

Cycloaliphatic monoamines are the monoamines in which a cycloaliphatic substituent is directly attached to the amine nitrogen through a carbon atom in the cyclic ring structure. Examples of cycloaliphatic monoamines include cyclohexylamines, cyclopentylamines, cyclohexenylamines, cyclopentenylamines, N-ethylcyclohexylamine and dicyclohexylamine. Examples of aliphatic-substituted, aromatic-substituted and heterocyclic-substituted cycloaliphatic monoamines are propyl-substituted cyclohexylamines, phenyl-substituted cyclopentylamines and pyranyl-substituted cyclohexylamine.

Aromatic amines include those monoamines in which one carbon atom of the aromatic ring structure is directly bonded to the amine nitrogen. The aromatic ring will usually be a mononuclear aromatic ring (i.e. a ring derived from benzene), but fused aromatic rings are also included, particularly those derived from naphthalene. Examples of aromatic monoamines include aniline, di(p-methylphenyl)amine, naphthylamine and N,N-dibutylaniline. Examples of aliphatic-substituted, cycloaliphatic-substituted and heterocyclic-substituted aromatic monoamines are p-ethoxyaniline, p-dodecylaniline, cyclohexyl-substituted naphthylamine and thienyl-substituted aniline.

The polyamines from which (C-3) is derived basically include alkyleneamines which essentially correspond to the general formula

in which t is an integer preferably less than 10, the radical A is a hydrogen atom or a group consisting essentially of hydrocarbons and preferably having up to 30 carbon atoms and in which the alkylene group is preferably a lower alkylene group having less than 8 carbon atoms. The alkyleneamines basically include methyleneamines, ethyleneamines, hexylenamines, heptylenamines, octylenamines and other polymethyleneamines. Specific examples are: ethylenediamine, triethylenetetramine, Propylenediamine, decamethylenediamine, octamethylenediamine, di-(heptamethylene)triamine, tripropylenetetramine, tetraethylenepentamine, trimethylenediamine, pentaethylenehexamine, di-(trimethylene)triamine. Higher homologues such as those obtained by condensing two or more of the alkyleneamines illustrated above are equally suitable.

Ethylene amines are particularly suitable. They are described in detail under the heading "Ethylene Amines" in Kirk Othmer's "Encyclopedia of Chemical Technology", Vol. 5, pages 898-905, Interscience Publishers, New York (1950). Such compounds are most conveniently prepared by the reaction of an alkylene chloride with ammonia. The reaction results in the formation of a rather complex mixture of alkylene amines, including cyclic condensation products such as piperazines. These mixtures can be used in the process of the invention. On the other hand, quite satisfactory products can also be obtained by the use of pure alkylene amines. An alkylene amine which is particularly suitable both for reasons of economy and for reasons of the effectiveness of the products derived therefrom is a mixture of ethylene amines prepared by the reaction of ethylene chloride and ammonia and having a composition corresponding to that of tetraethylene pentamine.

Hydroxyalkyl-substituted alkyleneamines, i.e., alkyleneamines having one or more hydroxyalkyl substituents on the nitrogen atoms, are equally contemplated for use in the present invention. The hydroxyalkyl-substituted alkyleneamines are preferably those in which the alkyl group is a lower alkyl group, i.e., a group having less than about 6 carbon atoms. Examples of such amines include N-(2-hydroxyethyl)ethylenediamine, N,N'-bis(2-hydroxyethyl)ethylenediamine, 1-(2-hydroxyethyl)piperazine, mono(hydroxypropyl)piperazine, dihydroxypropyl-substitutedtetraethylenepentamine, N-(3-hydroxypropyl)tetramethylenediamine, and 2-heptadecyl-1-(2-hydroxyethyl)imidazoline.

Higher homologues such as those obtained by condensation of the above-illustrated alkyleneamines or hydroxyalkyl-substituted alkyleneamines through amino groups or through hydroxy groups are equally suitable. It is clear that condensation through amino groups leads to a higher amine accompanied by removal of ammonia and that condensation through the hydroxy groups leads to a product with ether linkages accompanied by removal of water.

Heterocyclic mono- and polyamines can also be used to prepare the nitrogen-containing compositions (C-3). As used herein, the terminology "heterocyclic mono- and polyamine(s)" is intended to describe the heterocyclic amines that contain at least one primary or secondary amino group and at least one nitrogen atom as a heteroatom in the heterocyclic ring. However, as long as at least one primary or secondary amino group is present in the heterocyclic mono- and polyamines, the heteroatom in the ring can be a tertiary amine nitrogen atom; i.e., a nitrogen atom that does not contain a hydrogen atom directly bonded to the ring nitrogen atom. Heterocyclic amines can be saturated or unsaturated and can contain various substituents such as nitro, alkoxy, alkylmercapto, alkyl, alkenyl, aryl, alkaryl, or aralkyl substituents. In general, the total number of carbon atoms in the substituents will not exceed 20. Heterocyclic amines may contain heteroatoms other than nitrogen atoms, particularly oxygen and sulfur. Obviously, they may contain more than one nitrogen heteroatom. The 5- and 6-membered heterocyclic rings are preferred.

Among the suitable heterocycles are aziridines, azetidines, azolidines, tetra- and dihydropyridines, pyrroles, indoles, piperidines, imidazoles, di- and tetrahydroimidazoles, piperazines, isoindoles, purines, morpholines, thiomorpholines, N-aminoalkylmorpholines, N-aminoalkylthiomorpholines, N-aminoalkylpiperazines, N,N'-diaminoalkylpiperazines, azepines, azozines, azonines, azezines and tetra-, di- and perhydro derivatives of any of the foregoing compounds and mixtures of two or more of these heterocyclic amines. Preferred heterocyclic amines are the saturated 5- and 6-membered heterocyclic amines containing only nitrogen, oxygen and/or sulfur in the hetero ring, especially the piperidines, piperazines, thiomorpholines, morpholines, pyrrolidines and the like. Piperidine, aminoalkyl-substituted piperidines, piperazine, aminoalkyl-substituted piperazines, morpholine, aminoalkyl-substituted morpholines, pyrrolidine and aminoalkyl-substituted pyrrolidines are particularly preferred. Usually, the aminoalkyl substituents are substituted on a nitrogen atom forming part of the heterocycle. Specific examples of such heterocyclic amines include N-aminopropylmorpholine, N-aminoethylpiperazine and N,N'-diaminoethylpiperazine.

The nitrogen-containing compositions (C-3) obtained by reacting the succinic acid-producing compounds and the amines described above can be amine salts, amides, imides, imidazolines and mixtures thereof. To prepare the nitrogen-containing composition (C-3), one or more of the succinic acid-producing compounds and one or more of the amines are heated, optionally in the presence of a normally liquid, substantially inert organic liquid Solvent/diluent at an elevated temperature generally in the range of 80ºC to the decomposition point of the mixture or product. Normally temperatures in the range of 100ºC to 300ºC are used, provided that 300ºC is not above the decomposition point.

The succinic acid generating compound and the amine are reacted in sufficient amounts to provide at least about one-half of an equivalent of the amine per equivalent of the acid generating compound. Generally, the maximum amount of amine present will be about 2 moles of amine per equivalent of the succinic acid generating compound. For the purposes of this invention, 1 equivalent of the amine is the amount of amine equal to the total weight of amine divided by the total number of nitrogen atoms present. Therefore, octylamine has an equivalent weight equal to its molecular weight; ethylenediamine has an equivalent weight equal to one-half of its molecular weight, and aminoethylpiperazine has an equivalent weight equal to one-third of its molecular weight. The number of equivalents of succinic acid generating compound will vary with the number of succinic acid groups present therein, and generally there will be 2 equivalents of acylating reagent for each succinic acid group in the acylating agents. Conventional techniques can be used to determine the number of carboxyl functions (e.g., acid number, saponification number) and hence the number of equivalents of acylating reagent available for reaction with the amine. Additional details and examples of methods for preparing the nitrogen-containing compositions of the present invention by reacting succinic acid generating compounds and amines are contained, for example, in U.S. Patents 3,172,892, 3,219,666, 3,272,746 and 4,234,435.

Oxygen-bridged dispersants include the esters of the carboxylic acids described above, such as those described in the aforementioned U.S. Patents 3,381,022 and 3,542,678. As such, they contain acyl or, optionally, acylimidoyl groups. (An oxygen-bridged dispersant containing an acyloxy group as the polar group would be a peroxide, which would likely not be stable under all conditions of use of the compositions of the invention.) These esters are preferably prepared by conventional methods, usually the reaction (often in the presence of an acid catalyst) of the carboxylic acid generating compound with an aromatic compound such as a phenol or naphthol. The preferred hydroxy compounds are alcohols having up to 40 aliphatic carbon atoms. These can be monohydric alcohols such as methanol, ethanol, isooctanol, dodecanol, cyclohexanol, neopentyl alcohol, and monomethyl esters of ethylene glycol, or polyhydric alcohols including ethylene glycol, diethylene glycol, dipropylene glycol, tetramethylene glycol, pentaerythritol, tris-(hydroxymethyl)-aminomethane (THAM) and glycerin. Carbohydrates (e.g. sugar, starches, cellulose) are also suitable, as are partially esterified derivatives of polyhydric alcohols with at least three hydroxyl groups.

A particularly preferred hydroxy compound which is reacted with the succinic acid-producing compound is an organic hydroxy compound of the general formula

in which R¹⁶ and R¹⁷ are aliphatic groups which independently contain 1 to 8 carbon atoms, R¹⁸ is an aliphatic group having 1 to 8 carbon atoms and n is a number from 1 to 3. Preferably R¹⁶, R¹⁷ and R¹⁷ contain up to 3 carbon atoms and n is 1. The most preferred hydroxy compound is N,N-dimethylethanolamine.

The reaction is usually carried out at a temperature above 100ºC and typically at 150-300ºC. The esters may be neutral or acidic or they may contain unesterified hydroxyl groups according to a ratio or equivalents of acid generating compound to hydroxy compound equal to, greater than or less than 1:1.

It will be appreciated that the oxygen-bridged dispersants are normally essentially neutral or acidic. For the purposes of this invention, they are among the preferred ester dispersants.

It is possible to prepare mixed oxygen and nitrogen-bridged dispersants by simultaneously or, preferably, sequentially reacting the acylating agent with nitrogen-containing and hydroxy reagents in a ratio of 10:1 and 1:10, on an equivalent weight basis. The methods for preparing the mixed oxygen and nitrogen-bridged dispersants are generally the same as for the individual dispersants described, with the exception that two sources are used for group (ii). As noted above, substantially neutral or acidic dispersants are preferred, and a typical method for preparing mixed oxygen and nitrogen-bridged dispersants of this type (which are particularly preferred) is to react the acylating agent first with the hydroxy reagent and subsequently reacting the intermediate so obtained with a suitable nitrogen-containing reagent in an amount to obtain a substantially neutral or acidic product. The following non-limiting examples illustrate the process for preparing the carboxylic acid dispersant compositions useful in this invention:

Example (C-3)-1

A polyisobutenyl succinic anhydride is prepared by reacting a chlorinated polyisobutylene with maleic anhydride at 200°C. The polyisobutenyl group has an average molecular weight of 850 and the resulting alkenyl succinic anhydride has an acid number of 113 (corresponding to an equivalent weight of 500). To a mixture of 500 g (1 equivalent) of this polyisobutenyl succinic anhydride and 160 g of toluene is added 35 g (1 equivalent) of diethylenetriamine at room temperature. The addition is carried out in portions over a period of 15 minutes and an initial exothermic reaction causes the temperature to rise to 50°C. The mixture is then heated and a water-toluene azeotrope is distilled from the mixture. When no more water passes over, the mixture is heated to 150ºC under reduced pressure to remove the toluene. The residue is diluted with 350 g of mineral oil and this solution has a nitrogen content of 1.6%.

Example (C-3)-2

The procedure of Example (C-3)-1 is repeated using 31 g (1 equivalent) of ethylenediamine as the amine reactant. The nitrogen content of the resulting product is 1.4%.

Example (C-3)-3

The procedure of Example (C-3)-1 is repeated using 55.5 g (1.5 equivalents) of an ethyleneamine mixture having a composition corresponding to that of triethylenetetramine. The product obtained has a nitrogen content of 1.9%.

Example (C-3)-4

The procedure of Example (C-3)-1 is repeated using 55.0 g (1.5 equivalents) of triethylenetetramine as the amine reactant. The resulting product has a nitrogen content of 2.9%.

Example (C-3)-5

An acylated nitrogen composition is prepared according to the procedure of Example (C-3)-1 except that the reaction mixture contains 3800 g of the polyisobutenyl succinic anhydride, 376 g of a mixture of triethylenetetramine and diethylenetriamine (75:25, weight ratio) and 2785 g of mineral oil. The product has a nitrogen content of 2%.

Example (C-3)-6

A mixture of 510 parts (0.28 mole) of polyisobutene (Mn = 1845; Mw = 5325) and 59 parts (0.59 mole) of maleic anhydride is heated to 110°C. The mixture is heated to 190°C in 7 hours, during which time 43 parts (0.6 mole) of gaseous chlorine is added below the surface. At 190-192°C, an additional 11 parts (0.16 mole) of the chlorine is added over 3.5 hours. The reaction mixture is stripped with nitrogen while heating at 190-193°C for 10 hours. The residue is the desired polyisobutene-substituted succinic acylating agent having a saponification equivalent number of 87, determined according to ASTM Method D-94.

A mixture is prepared by adding 10.2 parts (0.25 equivalents) of a commercially available mixture of ethylene polyamines containing from about 3 to about 10 nitrogen atoms per molecule to 113 parts mineral oil and 161 parts (0.2 equivalents) of the substituted succinic acylating agent at 130°C. The reaction mixture is heated to 150°C in 2 hours and stripped with nitrogen. The reaction mixture is filtered to give the filtrate as an oil solution of the desired product.

Example (C-3)-7

A mixture of 100 parts (0.495 moles) polyisobutene (Mn = 2020; Mw = 6049) and 115 parts (1.17 moles) maleic anhydride is heated to 100°C. This mixture is heated to 184°C in 6 hours, during which time 85 parts (1.2 moles) of gaseous chlorine are added subsurface. At 184-189°C, an additional 59 parts (0.83 moles) of chlorine are added over 4 hours. The reaction mixture is stripped with nitrogen by heating at 186-190°C for 26 hours. The residue is the desired polyisobutene substituted succinic acylating agent having a saponification equivalent number of 87 as determined according to ASTM Method D-94.

A mixture is prepared by adding 57 parts (1.38 equivalents) of a commercial mixture of ethylene polyamines containing about 3 to 10 nitrogen atoms per molecule to 1067 parts of mineral oil and 893 parts (1.38 equivalents) of the substituted succinic acylating agent at 140-145°C. The reaction mixture is heated to 155°C in 3 hours and stripped with nitrogen. The reaction mixture is filtered to give the filtrate as an oil solution of the desired product.

Example (C-3)-8

1000 parts (3.09 mol) of hexadecyl succinic anhydride are mixed with 278 parts (3.12 mol) of N,N-dimethylethanolamine. The ingredients are heated to 93ºC and kept at this temperature for 1 hour. The product has a nitrogen content of 3.3%.

(C)(4) The antioxidant

Antioxidants that can be used according to the invention include alkylphenols, benzotriazoles and aromatic amines. The alkylphenol has the formula

The benzotriazole compound has the general formula

in which the radical R²³ is a methyl group. If the radical R²³ contains a carbon atom, the benzotriazole compound can be a tolyltriazole of the formula

Tolyltriazole is available under the trademark Cobratec TT-100 from Sherwin-Williams Chemical.

The aromatic amine has the general formula

in which the radical R²&sup4; has the general formula

in which the radical R²⁶ is a nonyl group. In a particularly advantageous embodiment, component (C) comprises a nonylated diphenylamine of the formula

(D) The fuel

The compositions of this invention, (A), (B) and (C)(4), can be added directly to fuels. Preferably, however, they are diluted with the fuel to form an additive concentrate. These concentrates typically contain from 10 to 80% by weight of the compositions of the invention and from 20 to 90% by weight of the fuel.

The fuel compositions of the present invention contain a major amount of a normally liquid fuel comprising

(1) a hydrocarbon-containing petroleum distillate fuel such as motor gasoline, according to ASTM specification D439, and diesel fuel or heating oil, according to ASTM specification D396. Normally liquid fuel compositions include non-hydrocarbon materials such as alcohols, ethers, organic nitro compounds and the like (e.g., methanol, ethanol, diethyl ether, methyl ethyl ether, nitromethane) as well as liquid fuels which are mixtures of one or more hydrocarbon fuels and one or more non-hydrocarbon materials are also within the scope of this invention. Examples of such mixtures are combinations of gasoline and ethanol and of diesel fuel and ether. Particularly preferred is gasoline, i.e. a mixture of hydrocarbons having an ASTM distillation range of 60ºC at the 10% distillation point to 205ºC at the 90% distillation point.

Other fuels that can be used are:

(2) synthetic ester base oils which are the reaction product of a monocarboxylic acid of the general formula

R¹&sup9;COOH

or a dicarboxylic acid of the general formula

with an alcohol of the general formula

R²¹(OH)n

wherein R¹⁹9 is a hydrocarbyl group having 4 to 24 carbon atoms, R²⁹0 is a hydrogen atom or a hydrocarbyl group having 4 to 50 carbon atoms, the residue R²¹ is a hydrocarbyl group having 1 to 24 carbon atoms, m is an integer from 0 to 6 and n is an integer from 1 to 6.

Suitable monocarboxylic acids are the isomeric carboxylic acids of pentanoic, hexanoic, octanoic, nonanoic, decanoic, undecanoic and dodecanoic acids. When R37 is hydrogen, suitable dicarboxylic acids are succinic, maleic, azelaic, suberic, sebacic, fumaric and adipic acid. When R37 is a hydrocarbyl group having 4 to 50 carbon atoms, suitable dicarboxylic acids are alkylsuccinic acids and alkenylsuccinic acids. Alcohols that can be used are methyl alcohol, ethyl alcohol, butyl alcohol, the isomeric pentyl alcohols, the isomeric hexyl alcohols, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, pentaerythritol, dipentaerythritol, trimethololpropane, bis-trimethololpropane. Specific examples of these esters include dibutyl adipate, di-(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, di-2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting 1 mole of sebacic acid with 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid, the ester formed by reacting 1 mole of adipic acid with 2 moles of a 9-carbon alcohol derived from the oxo process of a 1-butene dimer.

A partial list of companies that manufacture synthetic esters and their trademarks are: BASF as Glissofluid, Ciba-Geigy as Reolube, JCI as Emkarote, Oleofina as Radialube and the Emery Group of Henkel Corporation as Emery 2964, 2911, 2960, 2976, 2935, 2971, 2930 and 2957.

(3) The suitable mineral oils are mineral lubricating oils such as liquid petroleum-derived oils and solvent- or acid-treated mineral lubricating oils of the paraffin, naphthenic or mixed paraffin-naphthenic type. Also suitable are petroleum distillates such as VM & P naphtha and Stoddard solvents. Coal or shale-derived oils of lubricating viscosity are equally suitable. Synthetic lubricating oils include hydrocarbon oils and halogen-substituted hydrocarbon oils such as polymerized and copolymerized olefins (e.g. polybutylenes, polypropylenes, propylene-isobutylene copolymers and chlorinated polybutylenes); poly(1-hexenes), poly(1-octenes) and poly(1-decenes) and mixtures thereof; Alkylbenzenes (e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g. biphenyls, terphenyls and alkylated polyphenyls); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogues and homologues thereof.

Unrefined, refined and rerefined oils (as well as mixtures of two or more of any of these) can also be used in the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, shale oil obtained directly from retorting processes, a petroleum oil obtained directly from distillation or an ester oil obtained directly from an esterification process, used without further treatment, would be an unrefined oil. Refined oils are similar to unrefined oils except that they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, are known. Rerefined oils are obtained by processes similar to those used to obtain refined oils and applied to refined oils that have already been in use. Such rerefined oils are also known as reclaimed or reprocessed oils and are often additionally treated with techniques to remove spent additives and oil degradation products.

(4) Polyalphaolefins such as alkylene oxide polymers and copolymers and derivatives thereof in which the terminal hydroxyl groups have been modified, for example by esterification, etherification, represent another class of usable fuels. Examples of these are oils produced by polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g. methylpolyisopropylene glycol ether with an average molecular weight of about 1000, diphenyl ether of polyethylene glycol with a molecular weight of 500-1000, diethyl ether of polypropylene glycol with a molecular weight of 1000-1500, etc.) or mono- and polycarboxylic acid esters thereof, for example the acetic acid esters, the mixed C₃-C₈ fatty acid esters or the C₁₃-oxo acid diesters of tetraethylene glycol.

(5) Vegetable oils suitable as a fuel in this invention are those vegetable oils obtained without genetic modification, i.e. their content of monounsaturated compounds (as oleic acid) is less than 60%. Useful vegetable oils are canola oil, peanut oil, palm oil, corn oil, soybean oil, sunflower oil, cottonseed oil, safflower oil and coconut oil.

Generally, these fuel compositions contain an amount of the (A), (B), (C)(4) composition sufficient to improve one or more properties of the fuel, such as rust inhibition, dispersancy, etc. Usually Preferably, this amount is 0.005 to 0.5 vol.%, preferably 0.01 to 0.1 vol.%, based on the volume of these propellant or fuel compositions.

The propellant or fuel compositions may contain, in addition to the (A), (B), (C)(4) composition, other known additives. These include antiknock agents such as tetraalkyl lead compounds, lead volatilizers such as haloalkanes (e.g. ethylene dichloride and ethylene dibromide), deposit inhibitors or reducers such as triaryl phosphates, colorants, ignition accelerators, antioxidants such as 2,6-di-t-butyl-4-methylphenol, rust inhibitors such as alkylated succinic acids and anhydrides, bacteriostatic agents, stabilizers, metal deactivators, demulsifiers, top-lubricants and anti-icing agents.

The fuel additive compositions of this invention can be added directly to the fuel or they can be diluted with a substantially inert, normally liquid organic diluent such as naphtha, benzene, toluene, xylene or with a normally liquid fuel as described above to form an additive concentrate. These concentrates generally contain from 20 to 90% by weight of the composition of the invention and they can additionally contain one or more conventional additives known or described herein.

The fuel additive compositions of the invention can be provided in the form of a concentrate with less than the additive concentrations set forth above and then added directly to the fuel along with additional amounts of the compositions of the invention and other known additives, or they can be further diluted with additives prior to addition to the fuel until the additive concentration reaches the desired level.

The composition may comprise components (A), (B) and (C)(4) in the following ranges (parts by weight):

When the composition comprises components (A), (B) and (C)(4) with (D), the following table shows the ranges of these components in parts by weight:

The components of this invention are mixed together in accordance with the above ranges to effect dissolution.

Claims (1)

1. Composition comprising: (A) Esters from the transesterification of at least one animal or vegetable triglyceride oil of the general formula with an alcohol R⁴OH, where the radicals R¹, R² and R³ are aliphatic radicals having 6 to 24 carbon atoms and the radical R⁴ is an aliphatic radical having 1 to 10 carbon atoms; (B) a pour point depressant, and (C)(4) an antioxidant comprising (a) at least one alkylphenol of the general formula in which the radical R²² is t-butyl; and (b) a benzotriazole of the general formula in which the radical R²³ is a methyl group; and (c) at least one aromatic amine of the general formula in which the residue R²&sup4; and the radicals R²⁵ and R²⁶ are nonyl groups. 2. The composition of claim 1, wherein the vegetable triglyceride oil comprises sunflower oil, safflower oil, corn oil, soybean oil, rapeseed oil, meadowfoam oil or genetically modified sunflower oil, safflower oil, corn oil, soybean oil, rapeseed oil or meadowfoam oil. 3. A composition according to claim 1 or claim 2, wherein the transesterification is carried out in the presence of a catalyst comprising alkali or alkaline earth metal alkoxides and at a temperature from room temperature to the decomposition temperature of any reactant or product. 4. A composition according to any preceding claim, wherein the pour point depressant is a mixed ester having low temperature modification properties of a carboxy-containing copolymer, said copolymer having a reduced specific viscosity of from 0.05 to 2 and being derived from at least two monomers, one of said monomers being a low molecular weight aliphatic olefin, styrene or is a substituted styrene, wherein the substituent is a hydrocarbyl group containing from 1 to 18 carbon atoms, and the other of said monomers is an alpha, beta-unsaturated aliphatic acid, anhydride or ester thereof, said ester being substantially free of titratable acidity and characterized within its polymeric structure by the presence of at least one of each of three polar groups attached thereto derived from carboxy groups of the ester: (i) a carboxylic acid ester group having a relatively high molecular weight, wherein the carboxylic acid ester group has 8 to 24 aliphatic carbon atoms in the ester moiety. (ii) a carboxylic acid ester group having a relatively low molecular weight with 3 to 7 aliphatic carbon atoms in the ester residue, the molar ratio of (i): (ii) being (1-20): 1, and optionally (iii) a carbonylamino group derived from an amino compound having a primary or secondary amino group, wherein the molar ratio of (i) : (ii) : (iii) is (50-100) : (5-50) : (0.1- 15). 5. The composition of claim 4, wherein the carboxy-containing copolymer is a terpolymer having a molar proportion of styrene, a molar proportion of maleic anhydride and less than 0.3 molar proportions of a vinyl monomer. 6. Composition according to one of claims 1 to 3, wherein the pour point depressant is an acrylate polymer of the general formula in which the radical R⁵ is a hydrogen atom or a lower alkyl radical having 1 to about 4 carbon atoms, the radical R⁵ is a mixture of alkyl radicals having 4 to 24 carbon atoms and x is an integer providing a weight average molecular weight (Mw) of the acrylate polymer of from 5,000 to 1,000,000. 7. Composition according to one of claims 1 to 3, wherein the pour point depressant is a mixture of compounds of the general structural formula Ar-(R7 )-[-Ar'(R8 )]nAr" in which the radicals Ar, Ar' and Ar" are independently an aromatic radical having 1 to 3 aromatic rings, and the mixture includes compounds wherein radicals having 0 substituents, 1 substituent, 2 substituents and 3 substituents are present, the radicals R⁷ and R⁸ are independently an alkylene having 1 to 100 carbon atoms and n has the value 0 to 1000. 158. A composition according to any one of claims 1 to 3, wherein the pour point depressant is a nitrogen-containing polymethacrylate prepared by reacting a methacrylate ester of the general formula in which R9 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R10 is an alkyl group having 1 to 24 carbon atoms with a nitrogen-containing ester of 0.1 to 20 moles of the nitrogen-containing ester per mole of the methacrylate ester. 9. A fuel composition comprising a major amount of (D) a normally liquid fuel; the fuel comprising (1) a petroleum distillate; (2) a synthetic ester base oil comprising the reaction of a monocarboxylic acid of the general formula R¹&sup9;COOH or a dicarboxylic acid of the general formula with an alcohol of the general formula wherein R¹⁹9 is a hydrocarbyl group having 4 to 24 carbon atoms, R²⁰ is a hydrogen atom or a hydrocarbyl group having 4 to 50 carbon atoms, R²¹ is a hydrocarbyl group having 1 to 24 carbon atoms, m is 0 or an integer from 1 to 6, and t is an integer from 1 to 6; (3) a mineral oil; (4) a polyalphaolefin; and/or (5) a vegetable oil; and a minor amount of the composition according to any one of the preceding claims.