FIELD OF THE INVENTION

This invention relates to improved nitrogen-containing dispersants useful in lubricating oils and fuels.

BACKGROUND OF THE INVENTION

Polyisobutenyl succinimides, prepared from the reaction of polyisobutenyl succinic anhydride and ethylene polyamines (e.g., tetraethylene pentamine) are widely used in commercial lubricating oils as dispersants and have also been suggested for use in fuels as dispersants.

U.S. Patent 2,921,085 relates to the preparation of beta-aminopropionamides by reaction of an alkyl amine with an acrylate to form an alkyl aminopropionate and reaction of the latter compound with an amine. The resulting compounds are disclosed to have utility as surface active agents, specifically as emulsifying, wetting, foaming and detergent agents.

U.S. Patent 3,337,609 relates to adducts of hydroxyalkyl alkylene polyamines and acrylates. The resulting adducts are added to polyepoxides to provide compositions which are suitable for use as a barrier coating for polyethylene surfaces, and for additional end uses, such as in molding. In addition, the adducts are disclosed to be useful as catalysts in resin preparation and as corrosion inhibitors in water systems for ferrous metals.

U.S. Patent 3,417,140 relates to the preparation of amido-amine compositions, which are useful as epoxy resin curing agents, by reacting a polyalkylene polyamine and a fatty amine (comprising a mono- or diamine having as one of the substituents on a nitrogen atom a hydrocarbyl radical having 8 to 24 carbon atoms) with an alpha-beta unsaturated carbonylic compound. It is disclosed that this reaction occurs through the Michael addition of an amine group across the unsaturated group of the carbonylic compound and through the condensation of an amine group with the carbonylic group.

U.S. Pate t 3,247,163 also relates to curing agents for polyepoxide compositions, which curing agents are prepared by reacting an organic amine and an acrylate.

U.S. Patent 3,445,441 relates to amino-amido polymers characterized by being a reaction product of at least a polyamine and an acrylate type compound, such as methyl or ethyl acrylate, and methyl or ethyl methacrylate. The patent states that the polymers are useful in a wide variety of applications, such as floculating agents, water clarifying additives, corrosion inhibitors in oil and gas wells, and as lube oil additives. The patent further discloses that the polymers may be derivitized, including acylation with monocarboxylic acids and polycarboxylic acids, aliphatic dicarboxylic acids, aromatic dicarboxylic acids, for example, diglycolic, phthalic, succinic, etc., acids.

U.S. Patent 3,903,003 relates to lubricating compositions containing an amido-amine reaction product of a terminally carboxylated isoprene polymer which is formed by reacting, a terminally carboxylated substantially completely hydrogenated polyisoprene having an average molecular weight between about 20,000 and 250,000 and a

nitrogen compound of the group consisting of polyalkylene amines and hydroxyl polyalkylene amines.

U.S. Patent 4,493,771 relates to scale inhibiting with compounds containing quaternary ammonium and methylene phosphonic acid groups. These compounds are derivatives of polyamines in which the amine hydrogens have been substituted with both methylene phosphonic acid groups or their salts and hydroxypropyl quaternary ammonium halide groups. The patent discloses that any amine that contains reactive amino hydrogens can be utilized, for example, polyglycol amines, amido-amines, oxyacylated amines, and others .

U.S. Patent 4,459,241 contains a similar disclosure to U.S. Patent 4,493,771.

U.S. Patent 4,857,217 and European Patent Publication 319,299 relate to dispersants derived from amido-amines or thioamido-amine characterized by being a reaction product of a polyamine and disclosed alpha, beta-unsaturated compounds. The disclosed polyamines include alicyclic diamines such as 1 , 4 -di ( aminometh 1 ) cyclohexane .

SUMMARY OF THE INVENTION

According to the present invention, improved dispersants are provided which comprise adducts of (A) polymer-substituted mono- and dicarboxylic acid or anhydrides and (B) an amido-amine characterized by being a reaction product of an alpha, beta-unsaturated compound of the formula:

R >1 ^x -- C C - C - Y (I)

wherein X is sulfur or oxygen, Y is -OR ⁴ , -SR ⁴ , or -NR ⁴ (R ⁵ ) , and R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl, and bis (para-amino cyclohexyl) methane or its oligomers. The preferred dispersants comprise adducts of polyisobutenyl-substituted succinic a d or anhydride and amido-amine adducts of alkyl methacrylates (or alkyl acrylates) and bis (para-amino cyclohexyl) methane oligomers.

It has been found that the dispersants of the present invention exhibit improved dispersing properties compared to conventional polyisobutenyl succinimide dispersants, as illustrated by reduced sludge and/or varnish deposits on engine parts.

The dispersants of this invention can also provide enhanced resistance to degradation of fluoroelastomeric engine seals in use of these dispersants in crankcase lubricating oils for internal combustion engines (e.g., gasoline engines, diesel engines, methanol-containing fueled engines, etc.).

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides improved dispersants ich comprise adducts of (A) polymer-substituted mono- and dicarboxylic acid or anhydrides and (B) an amido-amine characterized by being a reaction product of (i) an alpha, beta-unsaturated compound of the formula:

R ² R ³ X R ¹ - C = C - C - Y (I) wherein X is sulfur or oxygen, Y is -OR ⁴ , -SR ⁴ , or -NR ⁴ (R ⁵ ) , and R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the

same or different and are hydrogen or substituted or unsubstituted hydrocarbyl, and (ii) bis (para-amino cyclohexyl) methane and oligomers thereof.

XAJ Polvmer-Substituted Acid/Anh dride Materials

The long chain hydrocarbyl polymer-substituted mono- or dicarboxylic acid material, i.e., acid, anhydride or acid ester used in this invention, includes the reaction produ a long chain hydrocarbon polymer, generally a polyo. .n, with a monounsaturated carboxylic reactant comprising at least one member selected from the group consisting of (i) monounsaturated C ₄ to C ₁₀ dicarboxylic acid (preferably wherein (a) the carboxyl groups are vicinyl, (i.e. located on adjacent carbon atoms) and (b) at least one, preferably both, of said adjacent carbon atoms are part of said mono unsaturation) ; (ii) derivatives of (i) such as anhydrides or C to C ₅ alcohol derived mono- or di-esters of (i) ; (iii) monounsaturated C ₃ to C _1Q monocarboxylic acid wherein the carbon-carbon double bond is conjugated to the carboxy group, i.e, of the structure

0

II

-C=C-C- ; and (iv) derivatives of (iii) such as C to C ₅ alcohol derived monoesters of (iii). Upon reaction with the polymer, the monounsaturation of the monounsaturated carboxylic reactant becomes saturated. Thus, for example, maleic anhydride becomes a polymer substituted succinic anhydride, and acrylic acid becomes a polymer substituted propionic acid.

Typically, from about 0.7 to about 4.0 (e.g., 0.8 to 2.6), preferably from about 1.0 to about 2.0, and most preferably from about 1.1 to about 1.7 moles of said

monounsaturated carboxylic reactant are charged to the reactor per mole of polymer charged.

Normally, not all of the polymer reacts with the monounsaturated carboxylic reactant and the reaction mixture will contain non-acid substituted polymer. The polymer-substituted mono- or dicarboxylic acid material (also referred to herein as " functional ized" polymer or polyolefin) , non-acid substituted polyolefin, and any other polymeric by-products, e.g. chlorinated polyolefin, (also referred to herein as "unfunctionalized" polymer) are collectively referred to herein as "product residue" or "product mixture" . The non-acid substituted polymer is typically not removed from the reaction mixture (because such removal is difficult and would be commercially infeasible) and the product mixture, stripped of any monounsaturated carboxylic reactant is employed for further reaction with the amine or alcohol as described hereinafter to make the dispersant.

Characterization of the average number of moles of monounsaturated carboxylic reactant which have reacted per mole of polymer charged to the reaction (whether it has undergone reaction or not) is defined herein as functionality. Said functionality is based upon (i) determination of the saponification number of the resulting product mixture using potassium hydroxide; and (ii) the number average molecular weight of the polymer charged, using techniques well known in the art. Functionality is defined solely with reference to the resulting product mixture. Although the amount of said reacted polymer contained in the resulting product mixture can be subsequently modified, i.e. increased or decreased by techniques known in the art, such modifications do not alter functionality as defined above. The terms "polymer substituted monocarboxylic acid material" and "polymer

substituted dicarboxylic acid material" as used herein are intended to refer to the product mixture whether it has undergone such modification or not.

Accordingly, the functionality of the polymer substituted mono- and dicarboxylic acid material will be typically at least about 0.5, preferably at least about 0.8 , and most preferably at least about 0.9 and will vary typically from about 0.5 to about 2.8 (e.g. , 0.6 to 2) , preferably from about 0.8 to about 1.4 , and most preferably from about 0.9 to about 1.3.

Exemplary of such monounsaturated carboxylic reactants are fumaric acid, itaconic acid, maleic acid, male ic anhydride , chloromaleic acid , chloromaleic anhydride, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid , and lower alkyl (e .g. , C- to C ₄ alkyl) acid esters of the foregoing, e.g. , methyl maleate, ethyl fumarate, methyl fumarate, etc.

Preferred olefin polymers for reaction with the monounsaturated carboxylic reactants to form reactant A are polymers comprising a major molar amount of C ₂ to C ₁₀ , e . g . , C ₂ to C ₅ monoo l e fin . Such olef ins include ethylene , propylene , butylene , isobutylene, pentene, octene-l, styrene, etc. The polymers can be homopolymers such as poly isobutylene, as well as copolymer s of two or more of such olefins such as copolymers of : ethylene and propylene ; bu tylene and isobutylene ; propylene and isobutylene ; etc . Mixtures of polymers prepared by polymerization of mixtures of isobutylene, butene-1 and butene-2 , e.g. , polyisobutylene wherein up to about 40% of the monomer units are derived from butene-1 and butene-2 , is an exemplary, and preferred, olefin polymer. Preferred are polyisobutenes as described in U.S. Patent 4 , 935, 576 (the disclosure of which is hereby incorporated by reference in its entirety) prepared as described therein.

Other copolymers include those in which a minor molar amount of the copolymer monomers, e.g., l to 10 mole %, is. a C ₄ to C ₁₈ non-conjugated diolefin, e.g., a copolymer of isobutylene and butadiene; or a copolymer of ethylene, propylene and 1,4-hexadiene; etc.

In some cases, the olefin polymer may be com¬ pletely saturated, for example an ethylene-propylene copolymer made by a Ziegler-Natta synthesis using hydrogen as a moderator to control molecular weight. Also useful are ethylene alpha-olefin copolymers having terminal unsaturation as described in U.S. Patent 4,668,834, the disclosure of which is hereby incorporated by reference in its entirety.

The olefin polymers used in the formation of reactant A wil have number average molecular weights within the range of about 300 to 10,000, generally from about 700 and about 5,000, preferably from about 1000 to 4,000, more preferably from about 1300 and about 3,000. Particularly useful olefin polymers have number average molecular weights within the range of about 1500 and about 3000, preferably with approximately one double bond (most preferably terminal double bond) per polymer chain. An especially useful starting material for highly potent dispersant additives useful in accordance with this invention is polyisobutylene, wherein up to about 40% of the monomer units are derived from butene-1 and/or butene-2. The number average molecular weight for such polymers can be determined by several known techniques. A convenient method for such determination is by gel permeation chromatography (GPC) which additionally provides molecular weight distribution information, see W. W. Yau, J.J. Kirkland and D.D. Bly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979.

The olefin polymers will generally have a molecular weight distribution (the ratio of the weight average molecular weight to number average molecular weight, i.e. fl _w /fl _n ) of from about 1.0 to 4.5, and more typically from about 1.5 to 3.0.

The polymer can be reacted with the monounsaturated carboxylic reactant by a variety of methods. For example, the polymer can be first halogenated, chlorinated or brominated to about 1 to 8 wt.%, preferably 3 to 7 wt. % chlorine, or bromine, based on the weight of polymer, by passing the chlorine or bromine through the polymer at a temperature of 60 to 250*C, preferably 110 to 160*C, e.g. 120 to 140'C, for about 0.5 to 10, preferably 1 to 7 hours. The halogenated polymer may then be reacted with sufficient monounsaturated carboxylic reactant at 100 to 250 *C, usually about 180' to 235*C, for about 0.5 to 10, e.g. 3 to 8 hours, so the product obtained will contain the desired number of moles of the monounsaturated carboxylic reactant per mole of the halogenated polymer. Processes of this general type are taught in U.S. Patents 3,087,436; 3,172,892; 3,272,746 and others. Alternatively, the polymer and the monounsaturated carboxylic reactant are mixed and heated while adding chlorine to the hot material. Processes of this type are disclosed in U.S. Patents 3,215,707; 3,231,587; 3,912,764; 4,110,349; 4,234,435; and in U.K. 1,440,219.

Alternately, the polymer and the monounsaturated carboxylic reactant can be contacted at elevated temperature to cause a thermal "ene" reaction to take place. Thermal "ene" reactions have been heretofore described in U.S. Patents 3,361,673 and 3,401,118, the disclosures of which are hereby incorporated by reference in their entirety.

Preferably, the polymers used in this invention contain less than 5 wt%, more preferably less than 2 wt%, and most preferably less than 1 wt% of a polymer fraction comprising polymer molecules having a molecular weight of less than about 300, as determined by high temperature gel premeation chromatography employing the corresponding polymer calibration curve. Such preferred polymers have been found to permit the preparation of reaction products, particularly when employing maleic anhydride as the unsaturated acid reactant, with decreased sediment. In the event the polymer produced as described above contains greater than about 5 wt% of such a low molecular weight polymer fraction, the polymer can be first treated by conventional means to remove the low molecular weight fraction to the desired level prior to initiating the ene reaction, and preferably prior to contacting the polymer with the selected unsaturated carboxylic reactant(s) . For example, the polymer can be heated, preferably with inert gas (e.g., nitrogen) stripping, at elevated temperature under a reduced pressure to volatilize the low molecular weight polymer components which can then be removed from the heat treatment vessel. The precise temperature, pressure and time for such heat treatment can vary widely depending on such factors as as the polymer number average molecular weight, the amount of the low molecular weight fraction to be emo e ; the particular monomers employed and other factors. Generally, a temperature of from about 60 to 100*C and a pressure of from about 0.1 to 0.9 atmospheres and a time of from about 0.5 to 20 hours (e.g., 2 to 8 hours) will be sufficient.

In this process, the selected polymer and monounsaturated carboxylic reactant and halogen (e.g., chlorine gas) , where employed, are contacted for a time and under conditions effective to form the desired polymer

substituted mono- or dicarboxylic acid material. Generally, the polymer and monounsaturated carboxylic reactant will be contacted in a unsaturated carboxylic reactant to polymer mole ratio usually from about 0.7:1 to 4:1, and preferably from about 1:1 to 2:1, at an elevated temperature, generally from about 120 to 260*C, preferably from about 160 to 240*C. The mole ratio of halogen to monounsaturated carboxylic reactant charged will also vary and will generally range from about 0.5:1 to 4:1, and more typically from about 0.7:1 to 2:1 (e.g., from about 0.9 to 1.4:1). The reaction will be generally carried out, with stirring for a time of from about 1 to 20 hours, preferably from about 2 to 6 hours.

By the use of halogen, about 65 to 95 wt. % of the polyolefin, e.g., polyisobutylene will normally react with the monounsaturated carboxylic acid reactant. Upon carrying out a thermal reaction without the use of halogen or a catalyst, then usually only about 50 to 75 wt. % of the polyisobutylene will react. Chlorination helps increase the reactivity. For convenience, the aforesaid functionality ratios of mono- or dicarboxylic acid producing units to polyolefin, e.g., 1.1 to 1.8, etc. are based upon the total amount of polyolefin, that is, the total of both the reacted and unreacted polyolefin, used to make the product.

The reaction is preferably conducted in the substantial absence of 0 ₂ and water (to avoid competing side reactions) , and to this end can be conducted in an atmosphere of dry N ₂ gas or other gas inert under the reaction conditions. The reactants can be charged separately or together as a mixture to the reaction zone, and the reaction can be carried out continuously, semi-continuously or batchwise. Although not generally necessary, the reaction can be carried out in the presence

of a liquid diluent or solvent, e.g., a hydrocarbon diluent such as mineral lubricating oil, toluene, xylene, dichlorobenzene and the like. The polymer substituted mono- or dicarboxylic acid material thus formed can be recovered from the liquid reaction mixture, e.g., after stripping the reaction mixture, if desired, with an inert gas such as N ₂ to remove unreacted unsaturated carboxylic reactant.

If desired, a catalyst or promoter for reaction of the olefin polymer and monounsaturated carboxylic reactant (whether the olefin polymer and monounsaturated carboxylic reactant are contacted in the presence or absence of halogen (e.g., chlorine)) can be employed in the reaction zone. Such catalyst of promoters include alkoxides of Ti, Zr, V and Al, and nickel salts (e.g., Ni acetoacetonate and Ni iodide) which catalysts or promoters will be generally employed in an amount of from about 1 to 5,000 ppm by weight, based on the mass of the reaction medium.

(B) Preparation of Amido-Amine Reactant B

As described above, the present invention comprises a reaction product of an alpha, beta ethylenically unsaturated compound of Formula (I) above and bis(para-amino cyclohexyl) methane (PACM) and oligomers thereof.

(i) Bis(Para-amino Cyclohexyl)Methane and its Oligomers

The PACM and PACM oligomer materials employed in this invention comprise bis(p-amino cyclohexyl) methane (PACM) in admixture with isomers thereof and analogues thereof containing, on average, from 2 to 6 or higher (usually 3 to 4) cyclohexyl rings per PACM oligomer

molecule. The PACM structure can be represented by Formula (II):

wherein x and y are the same or different and are integers of from 0 to 4, and preferably from 0 to 2, and wherein the sum of x + y is from 1 to 4, preferably from 1 to 2.

The total nitrogen content of the PACM oligomers will comprise generally from 8 to 16 wt.%, and preferably from 10 to 14 wt.%.

The PACM oligomers can be obtained e.g., by fractionation, or distillation, as a heavies by-product or bottoms from the PACM-containing product produced by high pressure catalytic hydrogenation of methylenedianiline. The hydrogenation of methylene dianiline and the separation of PACM oligomers from the resulting hydrogenation product can be accomplished by known means, including the processes disclosed in U.S. Patents 2,511,028; 2,606,924; 2,606,925; 2,606,928; 3,914,307; 3,959,374; 4,293,687; 4,394,523, 4,448,995 and 4,754,070, the disclosures of which are incorporated herein by reference in their entirety.

Bis(p-aminocyclohexyl)methane (PACM) in admixture with isomers thereof and analogs thereof containing three and four rings with either (1) an aliphatic hydrocarbon-substituted succinic anhydride or (2) an admixture of an aliphatic hydrocarbon-substituted phenol, formaldehyde and a fatty acid, such as oleic acid. This complex bis(primary amine) composition usually contains small amounts of methylene bis-aniline as well. These

bis (primary, amine) compositions are free from secondary amines and are available in solvent solution as PACM bottoms. Typically these compositions contain (by weight) about 16-23% bis (p-aminocyclohexyl) methane, and in addition, about 1-5% methylene bis-aniline, about 4-13% of isomers of bis (p-aminocyclohexyl) methane, and about 48-62% of analogs of bis (p-aminocyclohexyl) methane containing three and four rings. These complex compositions are commercially available from Air Products Company as PACM bottoms .

(ii) Alpha. Beta Ethylenically Unsaturated Compound

The alpha, beta ethylenically unsaturated compounds employed in this invention comprise at least one member selected from the group consisting of alpha, beta ethylenically unsaturated compounds of the formula:

R ² R ³ X

R l ¹ - C • - C ' - C Li - Y (I) wherein X is sulfur or oxygen, Y is -OR ⁴ , -SR ⁴ , or -NR ⁴ (R ⁵ ) , and R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl.

When R ¹ , R ² , R ³ , R ⁴ or R ⁵ are hydrocarbyl, these groups can comprise alkyl, cycloalkyl, aryl, alkaryl, aralkyl or heterocyclic, which can be substituted with groups which are substantially inert to any component of the reaction mixture under conditions selected for preparation of the amido-amine. Such substituent groups include hydroxy, halide (e.g., Cl, Fl, I, Br) , -SH and alkylthio. When one or more of R ¹ through R ⁵ are alkyl , such alkyl groups can be straight or branched chain, and will generally contain from 1 to 20, more usually from 1 to 10, and preferably from 1 to 4, carbon atoms. Illustrative of such alkyl groups are

methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl and the like. When one or more of R ¹ through R ⁵ are aryl, the aryl group will generally contain from 6 to 10 carbon atoms (e.g., pheny1, naphthyl) .

When one or more of R ¹ through R ⁵ are alkaryl, the alkaryl group will generally contain from about 7 to 20 carbon atoms, and preferably from 7 to 12 carbon atoms. Illustrative of such alkaryl groups are tolyl, m-ethyl- phenyl, o-ethyltolyl, and m-hexyltolyl. When one or more of R ¹ through R ⁵ are aralkyl, the aryl component generally consists of phenyl or ( C ₁ to C ₆ ) alkyl-sub- stituted phenol and the alkyl component generally contains from 1 to 12 carbon atoms, and preferably from 1 to 6 carbon atoms. Examples of such aralkyl groups are benzyl, o-ethylbenzyl, and 4-isobutylbenzyl. When one or more of R ¹ and R ⁵ are cycloalkyl, the cycloalkyl group will generally contain from 3 to 12 carbon atoms, and preferably from 3 to 6 carbon atoms. Illustrative of such cycloalkyl groups are cyclopropyl, cyclobutyl, cyclohexyl, cyclooctyl, and cyclododecyl. When one or more of R through R ⁵ are heterocyclic, the heterocyclic group generally consists of a compound having at least one ring of 6 to 12 members in which on oe more ring carbon atoms is replaced by oxygen or nitrogen. Examples of such heterocyclic groups are furyl, pyra yl, pyridyl, piperidyl, dioxanyl, tetra- hydrofuryl, pyrazinyl and 1,4-oxazinyl.

The alpha, beta ethylenically unsaturated carboxylate compounds employed herein have the following formula:

l ¹ - C - C - C - OR' (III)

wherein R ¹ , R ² , R ³ , and R ⁴ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above. Examples of such alpha, beta-ethylenically unsaturated carboxylate compounds of Formula III are acrylic acid, methacrylic acid, the methyl, ethyl, isopropyl, n-butyl, and isobutyl esters of acrylic and methacrylic acids, 2-butenoic acid, 2-hexenoic acid, 2-decenoic acid, 3 -me t hy 1 - 2 - hep t enoic acid, 3-methyl-2-butenoic acid, 3-phenyl-2-propenoic acid, 3-cyclohexyl-2-butenoic acid, 2-methyl-2-butenoic acid, 2-propyl-2-propenoic acid, 2-isopropyl-2-hexenoic acid, 2, 3-dimethyl-2-butenoic acid, 3-cyσlohexyl-2-methyl-2-pen- tenoic acid, 2-propenoic acid, methyl 2-propenoate, methyl 2-methyl 2-propenoate, methyl 2-butenoate, ethyl 2-hex- enoate, isopropyl 2-decenoate, phenyl 2-pentenoate, tertiary butyl 2-propenoate, octadecyl 2-propenoate, dodecyl 2-decenoate, cyclopropyl 2,3-dimethyl-2-butenoate, methyl 3-phenyl-2-propenoate, and the like.

The alpha, beta ethylenically unsaturated carboxylate thioester compounds employed herein have the following formula:

R ² R ³ O R ¹ - C - C - C - SR ⁴ (IV) wherein R ¹ , R , R ³ , and R ⁴ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above. Examples of such alpha, beta-ethylenically unsaturated carboxylate thioesters of Formula IV are methylmercapto 2-butenoate, ethylmercapto 2-hexenoate, isopropylmercapto 2-decenoate, phenylmercapto 2-pentenoate, tertiary butylmercapto 2-propenoate, octa- decylmercapto 2-propenoate, dodecylmercapto 2-decenoate, cyclopropylmercapto 2 , 3-dimethyl-2-butenoate, methyl¬ mercapto 3-phenyl-2-propenoate, methylmercapto 2-pro-

penoate, methylmercapto 2-methyl-2-propenoate, and the like.

The alpha, beta ethylenically unsaturated carboxya ide compounds employed herein have the following formula:

R ² R ^{3 Λ} t ¹ - C - C - C - N NRR ⁴ ((RR ⁵³ )] (V) wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above. Examples of alpha, beta-ethylenically unsaturated carboxyamides of Formula V are 2-butenamide, 2-hexenamide, 2-decenami.de, 3-methyl-2-heptenamide, 3-methyl-2-butenamide, 3-phenyl-2-propenamide, 3-cyclohexyl-2-butenamide, 2-methyl-2-butenamide, 2-propyl-2-propenamide, 2-isopropyl-2-hexenamide, 2 , 3-dimethyl-2-butenamide, 3-cyclohexyl-2-methyl-2-pentenamide, N-methyl 2-butenamide, N,N-diethyl 2-hexenamide, N-isopropyl 2-decenamide, N-phenyl 2-pentenamide, N-tertiary butyl 2-propenamide, N-octadecyl 2-propenamide, N-N-didodecyl 2-decenamide, N-cyclopropyl 2 , 3-dimethy 1-2-butenamide, N-raethyl 3-phenyl-2-propenamide, 2-propenamide, 2-methyl-2-pro- penamide, 2-ethyl-2-propenamide and the like.

The alpha, beta ethylenically unsaturated thiocarboxylate compounds employed herein have the following formula*

R ² R ³ S R ¹ - C - C - C - OR ⁴ (VI) wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above. Examples of alpha, beta-ethylenically unsaturated thiocarboxylate compounds of Formula VI are 2-butenthioic acid, 2-hexenthioiσ acid, 2-decenthioic acid, 3-methyl-2-heptenthioic acid.

3-methyl-2-butenthioic acid, 3-phenyl-2-propenthioic acid, 3-cyclohexyl-2-butenthioic acid, 2-methyl-2-butenthioic acid, 2-propyl-2-propenthioic acid, 2-isopropyl-2-hex- enthioic acid, 2, 3-dimethyl-2-butenthioic acid, 3-cyclo- hexyl-2-methyl-2-pententhioic acid, 2-propenthioic acid, methyl 2-propenthioate, methyl 2-methyl 2-propenthioate, methyl 2-butenthioate, ethyl 2-hexenthioate, isopropyl 2-decenthioate, phenyl 2-pententhioate, tertiary butyl 2-propenthioate, octadecyl 2-propenthioate, dodecyl 2-decenthioate, cyclopropyl 2, 3-dimethyl-2-butenthioate, methyl 3-phenyl-2-propenthioate, and the like.

The alpha, beta ethylenically unsaturated dithioic acid and acid ester compounds employed herein have the following formula:

R ² R ³ S

R ¹ i- C I = C I - C II - SR ⁴ A (VII) wherein R ¹ , R ² , R ³ , and R ⁴ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above. Examples of alpha, beta-ethylenically aturated dithioic acids and acid esters of Formula VII are 2 -butendithioic acid,

2-hexendithioic acid, 2-decendithioic acid, 3-methyl-2-hep- tendithioic acid, 3-methyl-2-butendithioic acid,

3-phenyl-2-propendithioic acid, 3-cyclohexyl-2-buten- dithioic acid, 2 -methy 1 -2 -but endi th ioic acid,

2-propyl-2-propendithioic acid, 2-isopropyl-2-hexendithioic acid, 2 , 3-dimethyl-2-butendithioic acid, 3-cyclo- hexyl-2-methyl-2-pentendithioic acid, 2-propendithioic acid, methyl 2-propendithioate, methyl 2-methyl 2-pro- pendithioate, methyl 2-butendithioate, ethyl 2-hex- endithioate, isopropyl 2-decendithioate , phenyl

2-pentendithioate, tertiary butyl 2-propendithioate, octadecyl 2-propendithioate, dodecyl 2-decendithioate,

cyclopropyl 2 , 3 -dimethyl-2-butendithioate, methyl 3-phenyl-2-propendithioate, and the like.

The alpha, beta ethylenically unsaturated thiocarboxyamide compounds employed herein have the following formula:

R ² R ³ S _R l_ c - C - C - NR (R ⁵ ) (VIII) wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above. Examples of alpha, beta-ethylenically unsaturated thiocarboxyamides of Formula VIII are 2-butenthioamide, 2-hexenthioamide, 2-decen- thioamide, 3-methyl-2-heptenthioamide, 3-methyl-2-buten- thioamide, 3-phenyl-2-propenthioamide, 3 -cyclohexyl -2 -buten- thioamide, 2-methyl-2-butenthioamide, 2-propyl-2-propen- thioamide, 2-isopropyl-2-hexenthioamide , 2,3-di- methyl-2-butenthioamide, 3 -cyclohexyl -2 -methyl-2-penten- thioamide, N-methyl 2-butenthioamide, N,N-diethyl 2-hexenthioamide, N-isopropyl 2-decenthioamide, N-phenyl 2-pententhioamide, N-tertiary butyl 2-propenthioamide, N-octadecyl 2-propenthioamide, N-N-didodecyl 2-decen- thioamide, N-cyclopropyl 2, 3-dimethyl-2-butenthioamide, N-methyl 3-phenyl-2-propenthioamide, 2-propenthioamide, 2-methyl-2-propenthioamide, 2-ethyl-2-propenthioamide and the like.

Preferred compounds for reaction with the PACM or PACM oligomers in accordance with this invention are lower alkyl esters of acrylic and (lower alkyl) substituted acrylic acid. Illustrative of such preferred compounds are compounds of the formula:

R ³ 0 CH ₂ "=- C - COR ⁴ (IX) where R ³ is hydrogen or a C _χ to C ₄ alkyl group, such as methyl, and R ⁴ is hydrogen or a C-^ to C ₄ alkyl

group, capable of being removed so as to form an amido group, for example, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, aryl, hexyl, etc. e.g., propyl acrylate and propyl methacrylate. In the preferred embodiments these compounds are acrylic and methacrylic esters such as methyl or ethyl acrylate, methyl or ethyl methacrylate. When the selected alpha, beta-unsaturated compound comprises a compound of Formula I wherein X is oxygen, the resulting reaction product with the polyamine contains at least one amido linkage (-C(0)N<) and such materials are herein termed "amido-amines." Similarly, when the selected alpha, beta unsaturated compound of formula I comprises a compound wherein X is sulfur, the resulting reaction product with the polyamine contains thioamide linkage (-C(S)N<) and these materials are herein termed "thioamido-amines." For convenience, the following discussion is directed to the preparation and use of amido-amines, although it will be understood that such discussion is also applicable to the thioamido-amines.

The type of amido-amine formed varies with reaction conditions. For example, a more linear amido-amine is formed where substantially equimolar amounts of the unsaturated carboxylate and polyamine are reacted. The presence of excesses of the ethylenically unsaturated reactant of Formula I tends to yield an amido-amine which is more cross-linked than that obtained where substantially equimolar amounts of reactants are employed. Where for economic or other reasons a cross-linked amido-amine using excess amine is desired, generally a molar excess of the ethylenically unsaturated reactant of about at least 10%, such as 10-300%, or greater, for example, 25-200%, is employed. For more efficient cross-linking an excess of carboxylated material should preferably be used since a cleaner reaction ensues. For example, a molar excess of

about 10-100% or greater such as 10-50%, but preferably an excess of 30-50%, of the carboxylated material. Larger excess can be employed if desired.

Preferably, the PACM oligomer reactant contains from 2 to 4 primary amine group per molecule, and the PACM or PACM oligomer and the unsaturated reactant of Formula I are contacted in an amount of from about 1 to 10, more preferably from about 2 to 6, and most preferably from about 3 to 5, equivalents of primary amine in the PACM oligomer reactant per mole of the unsaturated reactant of Formula I.

The reaction between the selected PACM or PACM oligomer and alpha, beta-ethenylically unsaturated compound is carried out at any suitable temperature. Temperatures up to the decomposition poi. s of reactants and products can be employed. In practice, one generally carries out the reaction by heating the reactants below 100*C, such as 80-90 ^* C, for a suitable period of time, such as a few hours. Where an acrylic-type ester is employed, the progress of the reaction can be judged by the removal of the alcohol in forming the amide. During the early part of the reaction alcohol is removed quite readily below 100*C in the case of low boiling alcohols such as ethanol or ethanol. As the reaction slows, the temperature is raised to push the polymerization to completion and the temperature may be raised to 150 ^* C toward the end of the reaction. Removal of alcohol is a convenient method of judging the progress and completion of the reaction which is generally continued until no more alcohol is evolved. Based on removal of alcohol, the yields are generally stoichiometric. In more difficult reactions, yield of at least 95% are generally obtained.

Similarly, it will be understood that the reaction of an ethylenically unsaturated carboxylate thioester of

Formula IV liberates the corresponding HSR ⁴ compound (e.g., H ₂ S when R ⁴ is hydrogen) as a by-product, and the reaction of an ethylenically unsaturated carboxyamide of Formula V liberates the corresponding HNR ⁴ (R ⁵ ) compound (e.g., ammonia when R ⁴ and R ⁵ are each hydrogen) as by-product.

The reaction time involved can vary widely depending on a wide variety of factors. For example, there is a relationship between time and temperature. In general, lower temperature demands longer times. Usually, reaction times of from' about 2 to 30 hours, such as 5 to 25 hours, and preferably 3 to 10 hours will be employed.

Although one can employ a solvent (e.g., a polar solvent such as tetrahydrof uran, methanol, ethanol, butanol, isopropanol, ethylene glycol, dioxane, and the like) , the reaction can be run without the use of any solvent. In fact, where a high degree of cross-linking is desired, it is preferable to avoid the use of a solvent and most particularly to avoid a polar solvent such as water. However, taking into consideration the effect of solvent on the reaction, where desired, any suitable solvent can be employed, whether organic or inorganic, polar or non-polar. The preferred solvnets are the lower alkanols (e.g., methanol, ethanol, propanol and isopropanol).

The amido (or thioamido) group residues of Reactants I servs tc link 2 or more (e.g., from 2 to 10, preferably from 2 to 6) molecules of the PACM oligomer through reaction with the primary N groups of the PACM oligomer. These reaxtions are of two types: the >C=C< group in the Reactant I undergoes an ene reaction with one H ₂ H- group to form an amine group (>CHCH ₂ -NH-) and the -C(X)-Y group in the Reactant I undergoes an elimination-addition reaction with a second H ₂ N- group to

eliminate HY and to form an amido (or thioa ido) group (-C(X)-NH-) as explained above.

Preparation of the Disoersant

The selected amido-amines (B) are readily reacted with the selected polymer substituted mono- or dicarboxylic acid material (A), e.g., alkenyl succinic anhydride, by heating an oil solution containing 5 to 95 wt. % of the polymer substituted dicarboxylic acid material to about 100 to 250 ^* C, preferably 125 to 175*C, generally for 1 to 10, e.g., 2 to 6 hours until the desired amount of water is removed. The heating is preferably carried out to favor formation of imides and/or amides, rather than salts. Generally from 1 to 5, preferably from about 1.5 to 3, moles of mono- or dicarboxylic acid moiety content (e.g., grafted maleic anhydride or grafted acrylic acid content) is used per primary nitrogen equivalent of the amido-amine (B).

Preferably, the polymer substituted mono- or dicarboxylic acid producing material and amido-amine compound (B) will be contacted for a time and under conditions sufficient to form an adduct having within its structure, on average, at least 0.5 (e.g., from 0.5 to 20), and preferably at least 1 (e.g., from 1 to 15) reactive amine group (i.e., primary and/or secondary amino groups) per molecule. The progress of this reaction can be followed by infra-red analysis.

The dispersant-forming reaction can be conducted in a polar or non-polar solvent (e.g., xylene, toluene, benzene and the like) , and is preferably conducted in the presence of a mineral or synthetic lubricating oil.

Preferably, the dispersant-forming reaction is conducted in a reaction zone in the substantial absence of a polar organic solvent to avoid competing side reactions

with those polar organic solvents (e.g., alcohols) which are reactive with the selected reactant (A) and to minimize the costs of, and waste streams generated in, the removal of such polar solvents from the dispersant products of this invention. Preferably, the dispersant-forming step's reaction zone contains not more than about 1 wt.% of polar organic solvent, based on the amount of amido-amine reactant (B) charged to this reaction zone. If polar organic solvents are employed in the formation of the amido-amine compound as described above, the solvent can be removed by distillation (e.g., under reduced pressure), insert gas stripping (e.g., N ₂ ) and the like.

The reaction can be conducted in a batchwise, semicontinuous or continuous manner, in one or more separate reaction vessels, which can comprise any of the conventional vessels employed for dispersant forming processes (e.g., stirred reactors). Generally, the reaction will be conducted under N or another inert gas to avoid oxidation of the reactants due to the presence of 0 ₂ containing gas (e.g. , air) . Inert gas sparging of the reaction mass can be employed continuously or semi-continuously to remove water of reaction from the product mixture.

The nitrogen-containing dispersant materials of the instant invention as described above are post-treated by contacting said nitrogen-containing dispersant materials with one or more post-treating reagents selected from the group consisting of boron oxide, boron oxide hydrate, boron halides, boron acids, esters of boron acids, carbon disulfide, sulfur, sulfur chlorides, alkenyl cyanides, aldehydes,, ketones, urea, thio-urea, guanidine, dicyanodiamide, hydrocarbyl phosphates, hydrocarbyl phosphites, hydrocarbyl thiophosphates, hydrocarbyl thiophosphites , c^ to C ₃₀ hydrocarbyl substituted

succinic acids and anhydrides (e.g., succinic anhydride, dodecyl succinic anhydride and the like) , maleic anhydride (or any of the above discussed monounsaturated carboxylic reactants useful in forming this invention) , phosphorus sulfides, phosphorus oxides, phosphoric acid, hydrocarbyl thiocyanates, hydrocarbyl isocyanates, hydrocarbyl isothiocyantes, epoxides, episulfides, formaldehyde or formaldehyde-producing compounds plus phenols, and sulfur plus phenols.

For example, the nitrogen containing dispersants can be treated with a boron compound selected from the class consisting of boron oxide, boron halides, boron acids and esters of boron acids in an amount to provide from about 0.1 atomic proportion of boron for each mole of said nitrogen composition to about 20 atomic proportions of boron for each atomic proportion of nitrogen of said nitrogen composition. Usefully the borated dispersants of the invention contain from about 0.05 to 2.0 wt.%, e.g., 0.05 to 0.7 wt.% boron based on the total weight of said borated nitrogen-containing dispersant compound. The boron, which appears to be in the product as dehydrated boric acid polymers (primarily (HB0 ) ₃ ), is believed to attach to the dispersant as amine salts, e.g., the metaborate salt of said amine dispersants.

Treating is readily carried out by adding from about 0.05 to 4, e.g. 1 to 3 wt.% (based on the weight of said nitrogen compound) of said boron compound, preferably boric acid which is most usually added as a slurry to said nitrogen compound and heating with stirring at from about 135*C. to 190, e.g., 140-170'C, for from 1 to 5 hours followed by nitrogen stripping at said temperature ranges. Or, the boron treatment can be carried out by adding boric acid to the hot reaction mixture of the dicarboxylic acid material and amine while removing water.

- 26 -

Since post-treating processes involving the use of these post-treating reagents is known insofar as application to reaction products of amine-containing ashless dispersants, further descriptions of these processes herein is unnecessary. In order to apply the prior art processes to the compositions of this invention, all that is necessary is that reaction conditions, ratio of reactants, and the like as described in the prior art, be applied to the novel compositions of this invention. The following U.S. patents are expressly incorporated herein by reference for their disclosure of post-treating processes and post-treating reagents applicable to the compositions of this invention: U.S. Pat. Nos. 3,087,936; 3,200,107;

3,254,025 3,256,185 3,278,550 3,282,955; 3,284,410 .3,338,832 3,344,069 3,373,111; 3,367,943 3,390,086 3,403,102 3,470,098; 3,502,677 3,513,093 3,533,945 3,639,242; 3,708,522 3,859,318 3,865,813 3,369,021; 3,184,411 3,185,645 3,245,908 3,245,910- 3,558,743 3,573,205 3,692,681 3,865,740; 3,954,639 3,458,530 3,390,086 3,185,704, 3,551,466 3,415,750 3,312,619 3,718,663; 3,652,616 4,338,205, 4,428,849 4,839,070; 4,839,071; 4,839,072; 4,839,073; U. 1,085,903; U.K. Pat. No. 1,162,436.

The nitrogen containing dispersant materials of this invention can also be treated with polymerizable lactones (such as epsilon-caprolactone) to form dispersant adducts having the moiety -[C(O) (CH ₂ ) _z O] _m H, wherein z is a number of from 4 to 8 (e.g., 5 to 7) and has an average value of from about 0 to 100 (e.g., 0.2 to 20). The dispersants of this invention can be post-treated with a C ₅ to C ₉ lactone, e.g., epsilon-caprolactone, by heating a mixture of the dispersant material and lactone in

a reaction vessel in the absence of a solvent at a temperature of about 50 ^* C to about 200*C, more preferably from about 75*C to about 180'C, and most preferably from about 90*C to about 160*C, for a sufficient period of time to effect reaction. Optionally, a solvent for the lactone, dispersant material and/or the resulting adduct may be employed to control viscosity and/or the reaction rates.

In one preferred embodiment, the C ₅ to C _g lactone, e.g., epsilon-caprolactone, is reacted with a dispersant material in a 1:1 mole ratio of lactone to dispersant material. In practice, the ration of lactone to dispersant material may vary considerably as a means of controlling the length of the seguence of the lactone units in the adduct. For example, the mole ratio of the lactone to the dispersant material may vary from about 10:1 to about 0.1:1, more preferably from about 5:1 to about 0.2:1, and most preferably from about 2:1 to about 0.4:1. It is preferable to maintain the average degree of polymerization of the lactone monomer below about 100, with a degree of polymerization on the order of from about 0.2 to about 50 being preferred, and from about 0.2 to about 20 being more preferred. For optimum dispersant performance, sequences of from about 1 to about 5 lactone units in a row are preferred.

Catalysts useful in the promotion of the lactone-dispersant material reactions are selected from the group consisting of stannous octanoate, stannous hexanoate, tetrabutyl titanate, a variety of organic based acid catalysts and amine catalysts, as described on page 266, and forward, in a book chapter authored by R.D. Lundberg and E. F. Cox, entitled "Kinetics and Mechanisms of Polymerization: Ring Opening Polymerization", edited by Frisch and Reegen, published by Marcel Dekker in 1969, wherein stannous octanoate is an especially preferred

catalyst. The catalyst is added to the reaction mixture at a concentration level of about 50 to about 10,000. parts per weight of catalyst per one million parts of the total ^' reaction mixture.

Exemplary of adducts formed by reaction of dispersant materials if this invention and epsilon- caprolactone are those adducts illustrated by the following equation:

[C(CH ₂ ) ₅ 0] _m H O

wherein is as defined above and wherein "E" is the polymer substituent group. The reactions of such lactones with dispersant materials containing nitrogen or ester groups is more completely described in U.S. Patents 4,486,326; 4,820,432; 4,828,742; 4,851,524; 4,866,135; 4,866,139; 4^866,140; 4,866,141; 4,866,142; and 4,866,187, the disclosure of each of which is hereby incorporated by reference in its entirety.

Further aspects of the present invention reside in the formation of metal complexes of the novel dispersant additives prepared in accordance with this invention. Suitable metal complexes may be formed in accordance with known techniques of employing a reactive metal ion species during or after the formation of the present dispersant materials. Complex forming metal reactants include the metal nitrates, thiocyanates, halides, carboxylates, phosphates, thio-phosphates, sulfates, and borates of transition metals such as iron, cobalt, nickel, copper, chromium, manganese, molybdenum, tungsten, ruthenium, palladium, platinum, cadmium, lead, silver, mercury, antimony and the like. Prior art disclosures of these complexing reactions may be also found in U.S. Patents 3,306,908 and Re. 26,433, the disclosures of which are hereby incorporated by reference in their entirety.

The processes of these incorporated patents, as applied to the compositions of this invention, and the post-treated compositions thus produced constitute a further aspect of this invention.

OLEAGINOUS COMPOSITIONS The dispersants of the present invention can be incorporated into a lubricating oil (or a fuel in any convenient way. Thus, these mixtures can be added directly to the lubricating oil (or fuel) by dispersing or dissolving the same in the lubricating oil (or fuel) at the desired level of concentration of the dispersant. Such blending into the additional lubricating oil (or fuel) can occur at room temperature or elevated temperatures. Alternatively, the dispersants can be blended with a suitable oil-soluble solvent/diluent (such as benzene, xylene, toluene, lubricating base oils and petroleum distillates, including the various normally liquid fuels

described in detail below) to form a concentrate, and then blending the concentrate with a lubricating oil (or fuel) to obtain the final formulation. Such dispersant concentrates will typically contain (on an active i ingredient (A.I.) basis) from about 3 to about 45 wt.%, and preferably from about 10 to about 35 wt.%, dispersant additive, and typically from about 30 to 90 wt.%, preferably from about 40 to 60 wt.%, base oil, based on the concentrate weight.

The oil-soluble additives of the present invention possess very good dispersant and antioxidant properties as measured herein in a wide variety of environments.

Accordingly, the additives are used by incorporation and dissolution into an oleaginous material such as fuels and lubricating oils. When the additives of this invention are used in normally liquid petroleum fuels such as middle distillates boiling from about 65* to 430 ^# C, including kerosene, diesel fuels, home heating fuel oil, jet fuels, etc., a concentration of the additives in the fuel in the range of typically from about 0.001 to about 0.5, and preferably 0.005 to about 0.15 weight percent, based on the total weight of the composition, will usually be employed. The properties of such fuels are well known as illustrated, for example, by ASTM Specifications D #396-73 (Fuel Oils) and D #439-73 (Gasolines) available from the American Society for Testing Materials ("ASTM"), 1916 Race Street, Philadelphia, Pennsylvania 19103. Normally liquid fuel compositions comprising non-hydrocarbonaceous materials such as alcohols, ethers, organo-nitro compounds and the like (e.g., methanol, ethanol, diethyl ether, methyl ethyl ether, nitromethane) are also within the scope of the invention. Such materials can be mixed with the hydrocarbon fuel in varying amounts of up to about 10-20% or more. For example, alcohols such

as methanol, ethanol, propanol and butanol, and mixtures of such alcohols are included in commercial fuels in amounts of up to about 10%. Other examples of materials which can be mixed with the fuels include diethyl ether, methyl ethyl ether, methyl tertiary butyl ether, and nitromethane. Also within the scope of the invention are liquid fuels derived from vegetable or mineral sources such as corn, alfalfa, shale and coal. Normally liquid fuels which are mixtures of one or more hydrocarbonaceous fuels and one or more non-hydrocarbonaceous materials are also contemplated.

The fuel compositions of this invention can contain, in addition to the products of this invention, other additives which are well known to those of skill in the art. These can include anti-knock agents such as tetraalkyl lead compounds, lead scavengers such as haloalkanes, deposit preventers or modifiers such as triaryl phosphates, dyes, cetane improvers, antioxidants such as 2 , 6-ditertiary-butyl-4-methylphenol, rust inhibitors, bacteriostatic agents, gum inhibitors, metal deactivators, upper cylinder lubricants and the like.

The additives of the present invention find their primary utility in lubricating oil compositions which employ a base oil in which the additives are dissolved or dispersed. Such base oils may be natural or synthetic. Base oils suitable for use in preparing the lubricating oil compositions of the present invention include those conventionally employed as crankcase lubricating oils for spark-ignited and compression-ignited internal combustion engines, such as automobile and truck engines, marine and railroad diesel engines, and the like. Advantageous results are also achieved by employing the additives of the present invention in base oils conventionally employed in and/or adapted for use as power transmitting fluids, universal tractor fluids and hydraulic fluids, heavy duty

- 32 -

hydraulic fluids, power steering fluids and the like. Gear lubr icants , industr ia l o i l s , pump oils and other lubricating oil compositions can also benefit from the incorporation therein of the additives of the present invention.

These lubricating oil formulations conventionally contain several different types of additives that will supply the characteristics that are required in the formulations. Among these types of additives are included vi scos ity index improvers , antioxidants , corros ion inhibitors , detergents , dispersants (especially ashless dispersants such as polyisobutylene succinimides and borated derivatives thereof) , pour point depressants , antiwear agents, friction modifiers, etc. as described in U. S. Patent 4 , 797 , 219, the disclosure of which is hereby incorporated by reference in its entirety. Some of these numerous additives can provide a multiplicity of effects, e.g. , a dispersant-oxidation inhibitor. This approach is well known and need not be further elaborated herein.

In the preparation of lubricating oil formulations it is common practice to introduce the additives in the form of 10 to 80 wt . % , e . g . , 20 to 80 wt . % active ingredient concentrates in hydrocarbon oil , e.g. , mineral lubricating oil, or other suitable solvent. Usually these concentrates may be diluted with 3 to 100, e.g. , 5 to 40 parts by weight cf lubricating oil, per part by weight of the additive package, in forming finished lubricants, e.g. , crankcase motor oils . The purpose of concentrates, of course, is to make the handling of the various materials less difficult and awkward as well as to facilitate solution or dispersion in the final blend . Thus , a dispersant would be usually employed in the form of a 40 to 50 wt. % concentrate, for example, in a lubricating oil fraction.

The additives of the present invention will be generally used in admixture with a lube oil basestock, comprising an oil of lubricating viscosity, including natural and synthetic lubricating oils and mixtures thereof.

Natural oils include animal oils and vegetable oils (e.g., castor, lard oil) liquid petroleum oils and hydrorefined, solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic and mixed paraffinic-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These are exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-poly isopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of poly-ethylene glycol having a molecular weight of 500-1000, diethyl ether of polypropylene glycol having a molecular weight of 1000-1500) ; and mono- and poly- carboxylic esters thereof, for example, the acetic acid esters, mixed C ₃ -C ₈ fatty acid esters and C ₁₃ Oxo acid diester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl

alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol) . 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 ph thai ate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C ₅ to C ₁ monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol , dipentaerythritol and tripentaerythritol .

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxysiloxane oils and silicate oils comprise another useful class of synthetic lubricants; they include tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra- (p-tertbutylphenyl) silicate, hexa-(4-methyl-2-pentoxy)disiloxane, poly (methyl )siloxanes and poly ( ethylphenyl ) siloxanes . Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decyl phosphonic acid) and polymeric tetrahydrofurans.

Unrefined, refined and rerefined oils can be used in the lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation or ester oil obtained directly from an

esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques, such as distillation, solvent extraction, acid or base extraction, filtration and percolation are known to those skilled in the art. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.

Compositions when containing these conventional additives are typically blended into the base oil in amounts effective to provide their normal attendant function. Representative effective amounts of such additives (as the respective active ingredients) in the fully formulated oil are illustrated as follows:

Wt.% A.I. Wt.% A.I.

Compositions oad

Viscosity Modifier Detergents Corrosion Inhibitor Oxidation Inhibitor Dispersant

Pour Point Depressant Anti-Foaming Agents Anti-Wear Agents Friction Modifiers Mineral Oil Base

When other additives are employed, it may be desirable, although not necessary, to prepare additive concentrates comprising concentrated solutions or disper¬ sions of the novel dispersants of this invention (in concentrate amounts hereinabove described) , together with one or more of said other additives (said concentrate when constituting an additive mixture being referred to herein as an additive-package) whereby several additives can be added simultaneously to the base oil to form the lubricating oil composition. Dissolution of the additive concentrate into the lubricating oil may be facilitated by solvents and by mixing accompanied with mild heating, but this is not essential. The concentrate or additive-package will typically be formulated to contain the additives in proper amounts to provide the desired concentration in the final formulation when the additive-package is combined with a predetermined amount of base lubricant. Thus, the dispersants of the present invention can be added to small amounts of base oil or other compatible solvents along with other desirable additives to form additive-packages containing active ingredients in collective amounts of typically from about 2.5 to about 90%, and preferably from about 15 to about 75%, and most preferably from about 25 to about 60% by weight additives in the appropriate proportions with the remainder being base oil.

The final formulations may employ typically about 10 wt. % of the additive-package with the remainder being base oil.

All of said weight percents expressed herein (unless otherwise indicated) are based on active ingredient (A.I.) content of the additive, and/or upon the total weight of any additive-package, or formulation which will

be the sum of the A.I. weight of each additive plus the weight of total oil or diluent.

This invention will be further understood by reference to the following examples, wherein all parts are parts by weight, unless otherwise noted and which include preferred embodiments of the invention. The PACM oligomer employed below is substantially free of polar solvent (less than about 1 wt.% polar organic solvent) and contains about 12.1 wt.% total nitrogen.

Example 1

An amido-amine (I) was prepared by reacting a PACM oligomer with methylacrylate at a 4:1 ratio of equivalents of primary amine in the PACM oligomer per mole of methylacrylate in an equal volume of methanol solvent at room temperature, heated slowly to 100*C with N ₂ stripping for about 4 hours to remove the methanol and to form an amido-amine product mixture substantially free of methanol (<1 wt.%) having 11.2 wt.% total nitrogen and 2.81 milliequivalents primary nitrogen per gram of sample.

Example 2

An amido-amine (II) was prepared similarly to that procedure described in Example 1, except that bis (para-amino cyclohexyl) methane ("monomer") was used instead of the PACM oligomer and except that a 2:1 PACM monomer: methylacrylate mole ratio was employed, to form an amido-amine product mixture containing 11.7 wt.% total nitrogen and 4.48 milliequivalents of primary nitrogen per gram of sample.

Example 3

An amido-amine (III) was prepared following the procedure of Example 2 except using a 1.6:1 PACM

monomer: methylacrylate mole ratio to form an amido-amine product mixture containing 11.4 wt. % total nitrogen and 3 .71 milliequivalents of primary nitrogen per gram of sample .

Example

About 100 g. of a polyisobutenyl-substituted succinic anhydride (PIBSA) derived from a polyisobutylene (fl _n of 2225) and having a Saponification No. of 37.4 (68 wt.% active ingredient) was mixed with 11.9 g. of amido-amine (I) and 29 g. of mineral lubricating oil (S150N) . The PIBSA and amido-amine (I) were contacted in a PIBSA:primary amine mole ratio of 1:1. The reaction mixture was then heated to 150'C for four hours while under light nitrogen stripping. The product was then nitrogen stripped for one hour and filtered. The product mixture oil solution analyzed for 0.69 wt.% total nitrogen.

Example 5

The procedure of Example 4 was repeated except that amido-amine (II) was employed and the polyisobutenyl succinic anhydride (PIBSA) and amido-amine (II) were contacted in a PIBSA:primary amine mole ratio of 1:1. The product mixture oil solution analyzed for 0.77 wt.% total nitrogen.

Example 6

The procedure of Example 4 was repeated except that amido-amine (III) was employed and the PIBSA and amido-amine (III) were contacted in a PIBSA:primary amine mole ratio of 1:1. The product mixture oil solution analyzed for 0.67 wt.% total nitrogen.

comparative Example 7

The procedure of Example 4 was repeated except that PACM monomer was used instead of the amido-amine (I) and the PIBSA and PACM monomer were charged in a ratio of two moles of PIBSA per mole of PACM monomer. The product mixture oil solution analyzed for 0.39 wt.% total nitrogen.

Comparative Example 8

The procedure of Comparative Example 7 was repeated except that the charge ratio was one mole of PIBSA per mole of PACM monomer and the product mixture oil solution analyzed for 0.63 wt.% total nitrogen.

The following lubricating oil compositions were prepared using the dispersants of Examples 4-5, Comparative Examples 7-8 and other comparative materials comprising commercial dispersants (A)-(C). The resulting compositions were then tested for sludge inhibition (via the SIB test) and varnish inhibition (via the VIB test) , as described below.

The SIB test has been found, after a large number of evaluations, to be an excellent test for assessing the dispersing power of lubricating oil dispersant additives.

The medium chosen for the SIB test was a used crankcase mineral lubricating oil composition having an original viscosity of about 325 SUS at 38*C that had been used in a taxicab that is driven generally for short trips only, thereby causing a buildup of a high concentration of sludge precursors. The oil that was used contained only a refined base mineral lubricating oil, a viscosity index- improver, a pour point depressant and zinc dialkyldithiophσsphate anti-wear additive. The oil contained no sludge dispersant. A quantity of such used

oil was acquired by draining and refilling the taxicab crankcase at 1000-2000 mile intervals.

The SIB test was conducted in the following manner: the aforesaid used crankcase oil, which was milky brown in color, was freed of sludge by centrifuging for one hour at about 39,000 gravities (gs.). The resulting clear bright red supernatant oil was then decanted from the insoluble sludge particles thereby separated out. However, the supernatant oil still contained oil-soluble sludge precursors which on heating under the conditions employed by this test will tend to form additional oil-insoluble deposits of sludge. The sludge inhibiting properties of the additives being tested were determined by adding to portions of the supernatant used oil, a small amount, such as 0.5, 1 or 2 weight percent, of the particular additive being tested. Ten grams of each blend being tested were placed in a stainless steel centrifuge tube and are heated at 135'C for 16 hours in the presence of air. Following the heating, the tube containing the oil being tested was cooled and then centrifuged for about 30 minutes at room temperature at about 39,000 gs. Any deposits of new sludge that form in this step were separated from the oil by decanting the supernatant oil and then carefully washing the sludge deposits with 25 ml of heptane to remove all remaining oil from the sludge and further centrifuging. The weight of the new solid sludge that has been formed in the test, in milligrams, was determined by drying the residue and weighing it. The results were reported as amount of precipitated sludge in comparison with the precipitated sludge of a blank not containing any additional additive, which blank was normalized to a rating of 10. The less new sludge precipitated in the presence of the additive, the lower the SIB value and the more effective was the additive as a sludge dispersant. In

other words, if the additive gave half as much precipitated sludge as the blank, then it would be rated 5.0 since the blank will be normalized to 10.

The VIB test was used to determine varnish inhibition. Here, each test sample consisted of 10 grams of lubricating oil containing a small amount of the additive being tested. The test oil to which the additive was admixed was of the same type as used in the above-described SIB test. Each ten gram sample was heat soaked overnight at about 140 C and thereafter centrifuged to remove the sludge. The supernatant fluid of each sample was subjected to heat cycling from about 150*C to room temperature over a period of 3.5 hours at a frequency of about 2 cycles per minute. During the heating phase, gas which was a mixture of about 0.7 volume percent S0 ₂ , 1.4 volume percent NO and balance air was bubbled through the test samples. During the cooling phase, water vapor was bubbled through the test samples. At the end of the test period, which sting cycle can be repeated as necessary to determine the inhibiting effect of any additive, the wall surfaces of the test flasks in which the samples were contained were visually evaluated as to the varnish inhibition. The amount of varnish imposed on the walls was rated to values of from 1 to 11 with the higher number being the greater amount of varnish, in comparison with a blank with no additive that is rated 11.

10.00 grams of SIB test oil were mixed with 0.05 grams of the products of the Examples as described and tested in the aforedescribed SIB and VIB tests. The data thereby obtained are summarized in Table II below.

- 42 -

Example

_A <1> _B (2) _c ( )

4

5 Comp. 7 Comp. 8

(1) Commercial borated polyisobutenyl succinimide dispersant derived from 950 fl _n PIB and polyethylene polyamine.

(2) Commercial borated polyisobutenyl succinimide dispersant derived from 1300 f^ PIB and polyethylene polyamine.

(3) Commercial borated polyisobutenyl succinimide dispersant derived from 2200 fl _n PIB and polyethylene polyamine.

The above data thereby obtained show that the dispersants of this invention have excellent SIB/VIB performance and sludge and varnish inhibiting properties.

- The improved inertness to fluoroelastomer seals was measured in test oils (S150N mineral oil) containing 6 wt.% of the dispersant candidate was used. These test oils were used to age Viton fluoroelastomer test samples for 7 days at 150'C. The change in the elongation of the test samples was measured, and the data thereby obtained is summarized in Table III below.

(1) Wt.% total N in test dispersant.

The data in Tables II and III thereby show that the dispersants of the present invention provide improved seal inertness at higher nitrogen levels which simultaneously providing improved dispersancy performance as measured by sludge performance and varnish inhibition.

A series of lubricating formulations were prepared which contained 6 vol% of the novel dispersants formed in Examples 4-6, respectively. Each lubricating composition also contained mineral lubricating oil, a mixture of overbased Mg sulfonate detergent inhibitor and overbased Ca sulfonate detergent inhibitor, zinc dialkyl dithiophosphate antiwear agent, antioxidant and ethylene propylene viscosity index improver.

The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.