US20100099588A1

US20100099588A1 - Dispersant Combination for Improved Transmission Fluids

Info

Publication number: US20100099588A1
Application number: US12/523,339
Authority: US
Inventors: Calvin A. James; Craig D. Tipton; William D. Abraham; Edward J. Konzman
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 2007-01-30
Filing date: 2008-01-22
Publication date: 2010-04-22
Also published as: EP2109659B1; JP2010516866A; CA2676290C; WO2008094781A3; JP5414537B2; WO2008094781A2; CA2676290A1; EP2109659A2

Abstract

A lubricant composition of an oil, a dispersant viscosity modifier of a poly(meth)acrylate copolymer having a nitrogen-containing monomer in an amount to provide at least about 0.4 percent by weight nitrogen to the copolymer, and a succinimide dispersant prepared in the substantial absence of chlorine gives good performance as a transmission fluid.

Description

BACKGROUND OF THE INVENTION

The present invention relates to the field of additives for fluids such as automatic transmission fluids, traction fluids, fluids for continuously variable transmissions (CVTs), dual clutch automatic transmission fluids, farm tractor fluids, and engine lubricants. The fluids may also be used for lubricating devices such as gear boxes, transfer cases, and chains.
It is known to add various additives to an oil of lubricating viscosity for automatic transmission fluids (hereinafter referred to as ATF) to improve resistance to wear, decrease anti-shudder properties and provide the appropriate friction properties. Friction properties of an ATF have to be balanced to provide high dynamic torque for efficient clutch engagement capacity and high static friction for good clutch holding. The ATF also has to provide a positive friction versus speed curve slope for good anti-shudder durability. These competing requirements are difficult to balance. In addition antiwear properties need to be sufficient for gear durability.
In addition, certain modern specifications for ATFs are difficult to achieve when one uses relatively poorer oils such as API Group II oils, which contain a considerable amount of volatile and unsaturated (cycloparaffinic) components. In order to obtain automotive service credentials with reasonable and cost-effective additive treat rates with these oils, one needs to effect a careful balance of sludge handling, anti-wear, anti-oxidancy, and friction properties.
A great number of additives have been proposed for lubricating oil compositions generally. Among these are dispersant-viscosity improvers, also known as dispersant-viscosity modifiers (DVMs) as disclosed, for instance, in U.S. Pat. No. 6,881,780, Bryant et al., Apr. 19, 2005. Other additives include succinimide dispersants as disclosed, for instance, in U.S. Application 2005/0202981, Eveland et al., published Sep. 15, 2005. Additives and formulations for lubricating automatic transmissions have been described in a great number of patents and patent applications, including, recently, U.S. Application 2006/0172899, Tipton et al., Aug. 3, 2006.
The present invention, therefore, solves the problem of achieving such a balance by employing in such a formulation a high nitrogen-content dispersant viscosity modifier in combination with a succinimide dispersant prepared by a “direct alkylation” process, described below. Such formulations may also impart good friction and high temperature oxidation performance at a relatively low treat rate

SUMMARY OF THE INVENTION

The present invention provides A lubricant composition comprising:
(a) an oil of lubricating viscosity;
(b) a dispersant viscosity modifier comprising a poly(meth)acrylate copolymer containing a nitrogen-containing monomer in an amount to provide at least about 0.4 percent by weight nitrogen to said dispersant viscosity modifier; and
(c) a succinimide dispersant prepared from reaction of an amine with a hydrocarbyl-substituted succinic acylating agent prepared by reaction of a polyalkene, at least about 70 percent of the chains thereof containing a terminal vinylidene end group, with maleic anhydride in the substantial absence of chlorine.

DETAILED DESCRIPTION OF THE INVENTION

Various preferred features and embodiments will be described below by way of non-limiting illustration.
One component of the present invention is an oil of lubricating viscosity, which can be present in a major amount, for a lubricant composition, or in a concentrate forming amount, for a concentrate. Suitable oils include natural and synthetic lubricating oils and mixtures thereof. In a fully formulated lubricant, the oil of lubricating viscosity is generally present in a major amount (i.e. an amount greater than 50 percent by weight). Typically, the oil of lubricating viscosity is present in an amount of 75 to 95 percent by weight, and often greater than 80 percent by weight of the composition. In a concentrate, the amount of oil will be reduced, e.g., 20 to 80 percent or 30 to 60 percent.
Natural oils useful in making the inventive lubricants and functional fluids include animal oils and vegetable oils as well as mineral lubricating oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic/-naphthenic types which may be further refined by hydrocracking and hydrofinishing processes.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins, also known as polyalphaolefins; polyphenyls; alkylated diphenyl ethers; alkyl- or dialkylbenzenes; and alkylated diphenyl sulfides; and the derivatives, analogs and homologues thereof. Also included are alkylene oxide polymers and inter-polymers and derivatives thereof, in which the terminal hydroxyl groups may have been modified by esterification or etherification. Also included are esters of dicarboxylic acids with a variety of alcohols, or esters made from C5 to C12 monocarboxylic acids and polyols or polyol ethers. Other synthetic oils include silicon-based oils, liquid esters of phosphorus-containing acids, and polymeric tetrahydrofurans,
Unrefined, refined and rerefined oils, either natural or synthetic, 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. Refined oils have been further treated in one or more purification steps to improve one or more properties. They can, for example, be hydrogenated, resulting in oils of improved stability against oxidation.
In one embodiment, the oil of lubricating viscosity is an API Group II, Group III, Group IV, or Group V oil, including a synthetic oil, or mixtures thereof. These are classifications established by the API Base Oil Interchangeability Guidelines. Both Group II and Group III oils contain <0.03 percent sulfur and >99 percent saturates. Group ii oils have a viscosity index of 80 to 120, and Group III oils have a viscosity index >120, Polyalphaolefins are categorized as Group IV. The oil can also be an oil derived from hydroisomerization of wax such as slack wax or a Fischer-Tropsch synthesized wax. Group V is encompasses “all others” (except for Group 1, which contains >0.03% S and/or <90% saturates and has a viscosity index of 80 to 120). In certain embodiments, the present invention may be used in Group II oils, which may especially reveal its benefits.
The oils of the present invention can encompass oils of a single viscosity range or a mixture of high viscosity and low viscosity range oils. In one embodiment, the oil exhibits a 100° C. kinematic viscosity of 1 or 2 to 8 or 10 mm²/sec (cSt). The overall lubricant composition may be formulated using oil and other components such that the viscosity at 100° C. is 1 or 1.5 to 10 or 15 or 20 mm²/sec and the Brookfield viscosity (ASTM-D-2983) at −40° C. is less than 20 or 15 Pa-s (20,000 cP or 15,000 cP), or less than 10 Pa-s, even 5 or less.
Another component of the present invention is a dispersant viscosity modifier, in particular, a dispersant viscosity modifier comprising a polyacrylate or polymethacrylate (hereinafter referred to as “poly(meth)acrylate”) copolymer containing a nitrogen-containing monomer Such materials typically include monomer-derived units from a monomer composition comprising one or more (meth)acrylates (that is, acrylates or methacrylates) of the formula (I), in which R denotes hydrogen or methyl and R¹denotes hydrogen or a linear or branched alkyl radical having 1 to 40 carbon atoms.
Suitable monomers according to formula (I) include (meth)acrylates which are derived from saturated alcohols, such as methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, tert-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, b 2-ethylhexyl(meth)acrylate, heptyl(meth)acrylate, 2-tert-butylheptyl(meth)acrylate, octyl(meth)acrylate, 3-isopropylheptyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate, undecyl(meth)acrylate, 5-methylundecyl(meth)acrylate, dodecyl(meth)acrylate, 2-methyldodecyl(meth)acrylate, tridecyl(meth)acrylate, 5-methyltridecyl(meth)acrylate, tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, 2-methylhexadecyl(meth)acrylate, heptadecyl(meth)acrylate, 5-isopropylheptadecyl(meth)acrylate, 4-tert-butyloctadecyl(meth)acrylate, 5-ethyloctadecyl(meth)acrylate, 3-isopropyloctadecyl(meth)acrylate, octadecyl(meth)acrylate, nonadecyl(meth)acrylate, eicosyl(meth)acrylate, cetyleicosyl(meth)acrylate, stearyleicosyl(meth)acrylate, docosyl(meth)acrylate and/or eicosyttetratriacontyl(meth)acrylate; (meth)acrylates which are derived from unsaturated alcohols, such as 2-propynyl(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, oleyl(meth)acrylate; cycloalkyl(meth)acrylates, such as cyclopentyl(meth)acrylate, 3-vinylcyclohexyl(meth)acrylate, cyclohexyl(meth)acrylate, and bornyl(meth)acrylate.
Furthermore, the monomer composition may comprise one or more (meth)acrylates of the formula (I) in which R denotes hydrogen or methyl and R¹denotes an alkyl radical substituted by an OH group and having 2 to 20 carbon atoms or denotes an alkoxylated radical of the formula (II) in which R³and R⁴independently represent hydrogen or methyl, R⁵represents hydrogen or an alkyl radical having 1 to 40 carbon atoms and n represents an integer from 1 to 90.
Such (meth)acrylates are known to a person skilled in the art and include hydroxyalkyl(meth)acrylates, such as 3-hydroxypropyl methacrylate, 3,4-dihydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2,5-dimethyl-1,6-hexanediol(meth)acrylate, 1,10-decanediol(meth)acrylate, 1,2-propanediol(meth)acrylate; polyoxyethylene and polyoxypropylene derivatives of (meth)acrylic acid, such as triethylene glycol(meth)acrylate, tetraethylene glycol(meth)acrylate and tetrapropylene glycol(meth)acrylate. (The products from the polyols are believed to comprises largely the mono(meth)acrylates).
As otherwise stated, the poly(meth)acrylate backbone may comprise acrylic or methacrylic ester monomers having an alcohol-derived moiety of the ester having 1 to 40 or 1 to 30 carbon atoms, or 2 to 24 carbon atoms, or mixtures thereof. Certain esters include methyl esters, ethyl, butyl, C9-11, and C12-18 esters. In one embodiment a suitable (meth)acrylate is methyl methacrylate. In other embodiments, mixtures of alcohols of 2 to 11 (or 9 to 11) or 1 to 4 carbon atoms, alone or further in combination with alcohols of 12 to 24 (or 12 to 18) carbon atoms may be used, as described in U.S. Pat. No. 6,881,780 or 6,124,249.
Suitable nitrogen-containing monomers for use in the DVM include nitrogen-containing (meth)acrylate (that is, acrylate or methacrylate) monomers such as amides or nitrogen-containing esters. Suitable amides include the condensation products of (meth)acrylic acid with ammonia, monoamines, diamines, or polyamines. The amine used to form the amide will normally contain at least one, and in certain embodiments exactly one, N—H group capable of condensing with carboxylic acid functionality, to form nitrogen-containing carboxylic derivatives with dispersant functionality.
Suitable amines include aromatic amines wherein a carbon atom of the aromatic ring structure is attached directly to the amino nitrogen. The amines may be monoamines or polyamines. The aromatic ring will typically be a mononuclear aromatic ring (i.e., one derived from benzene) but can include fused aromatic rings, especially those derived from naphthalene, Examples of aromatic amines include aniline, N-alkylanilines such as N-methyl aniline, and N-butylaniline, di-(para-methylphenyl)amine, naphthylamine, 4-amino-diphenylamine, N,N-dimethylphenylenediamine, 4-(4-nitrophenylazo)aniline (disperse orange 3), sulfamethazine, 4-phenoxyaniline, 3-nitroaniline, 4-aminoacetanilide 4-amino-2-hydroxy-benzoic acid phenyl ester (phenyl amino salicylate), N-(4-amino-5-methoxy-2-methyl-phenyl)-benzamide (fast violet B), N-(4-amino-2,5-dimethoxy-phenyl)-benzamide (fast blue RR), N-(4-amino-2,5-diethoxy-phenyl)-benzamide (fast blue BB), N-(4-amino-phenyl)-benzamide and 4-phenylazoaniline. Other examples include para-ethoxyaniline, para-dodecylaniline, cyclohexyl-substituted naphthylamine, and thienyl-substituted aniline. Examples of aromatic amines also include amino-substituted aromatic compounds and amines in which the amine nitrogen is a part of an aromatic ring, such as 3-aminoquinoline, 5-aminoquinoline, and 8-aminoquinoline. Also included are aromatic amines such as 2-aminobenzimidazole, which contains one secondary amino group attached directly to the aromatic ring and a primary amino group attached to the imidazole ring. Other amines include N-(4-anilinophenyl)-3-aminobutanamide (i.e., φ-NH-φ-NH—COCH₂CH(CH₃)NH₂). Additional aromatic amines include aminocarbazoles, aminoindoles, aminopyrroles, amino-indazolinones, aminoperimidines, mercaptotriazoles, aminophenothiazines, aminopyridiens, aminopyrazines, aminopyrimidines, pyridines, pyrazines, pyrimidines, aminothiadiazoles, aminothiothiadiazoles, and aminobenzotriaozles. Other aromatic amines include 3-amino-N-(4-anilinophenyl)-N-isopropyl butanamide, and N-(4-anilinophenyl)-3-{(3-aminopropyl)-(cocoalkyl)amino}butanamide. Other aromatic amines include various aromatic amine dye intermediates containing multiple aromatic rings linked by, for example, amide structures. Examples include materials of the general structure φ-CONH-φ-NH₂where the phenyl groups may be further substituted. Aromatic amines include those in which the amine nitrogen is a substituent on an aromatic carboxylic compound, that is, the nitrogen is not sp²hybridized within an aromatic ring. Certain aromatic amines, such as alkylated diphenylamines, may be used as antioxidants. To the extent that these materials will condense with a carboxylic functionality, they may also be suitable
Aromatic amines can be used alone or in combination with each other or in combination with or aliphatic or cycloaliphatic amines. The amount of such an aliphatic or cycloaliphatic amine may, in some embodiments, be a minor amount compared with the amount of the aromatic amine.
Aliphatic or cycloaliphatic amines include monoamines having, e.g., 1 to 8 carbon atoms, such as methylamine, ethylamine, and propylamine, as well as various higher amines. Aliphatic diamines or polyamines can also be used, and in certain embodiments they will have only a single primary or secondary amino group. Examples include dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, dimethylaminoethylamine, diethylaminoethylamine, dibutylaminoethylamine, 1-(2-aminoethyl)piperidine, 1-(2-aminoethyl)pyrrolidone, aminoethylmorpholine, and aminopropylmorpholine.
In certain embodiments, the amine component may comprise an amine having at least two N—H groups capable of condensing with carboxylic acid functionality, to serve to link together two polymers containing carboxylic acid functionality. Examples of such linking amines include ethylene diamine, 2,4-diaminotoluene, phenylene diamine, propylene diamine, hexamethylene diamine, and α,β-polyalkylenediamines.
The nitrogen-containing monomer units may also include one or more (meth)acrylates or (meth) acrylamides of the formula (III), in which R denotes hydrogen or methyl, X denotes oxygen or an amino group of the formula —NH—or —NR⁷—, in which R⁷represents an alkyl radical having 1 to 40 carbon atoms, and R⁶denotes a linear or branched alkyl radical substituted by at least one —NR⁸R⁹group and having 2 to 20, or 2 to 6, carbon atoms, R⁸and R⁹independently representing hydrogen or an alkyl radical having 1 to 20 or 1 to 6 carbon atoms, or in which R⁸and R⁹, including the nitrogen atom and optionally a further nitrogen or oxygen atom, form a 5- or 6-membered ring which optionally may be substituted by a C1-C6-alkyl group.
The (meth)acrylates or the (meth)acrylamides according to formula (III) include amides of (meth)acrylic acid, such as N-(3-dimethylaminopropyl)methacrylamide, N-(diethylphosphono)methacrylamide, 1-methacryloylamido-2-methyl-2-propanot, N-(3-dibutylaminopropyl)methacrylamide, N-tert-butyl-N-(diethylphosphono)methacrylamide, N,N-bis(2-diethylaminoethyl)methacrylamide, 4-methacryloylamido-4-methyl-2-pentanol, N-(methoxymethyl)methacrylamide, N-(2-hydroxyethyl)methacrylamide, N-acetylmethacrylamide, N-(dimethylaminoethyl)methacrylamide, N-methyl-N-phenyl-methacrylamide, N,N-diethylmethacrylamide, N-methylmethacrylamide, N,N-dimethylmethacrylamide, N-isopropylmethacrylamide; aminoalkyl methacrylates, such as dimethylaminoethyl methacrylate, tris(2-methyacryloyloxyethyl)amine, N-methylformamidoethyl methacrylate, 2-ureidoethyl methacrylate; heterocyclic(meth)acrylates, such as 2-(1-imidazolyl)-ethyl(meth)acrylate, 2-(4-morpholinyl)ethyl-(meth)acrylate and 1-(2-methacryloyloxyethyl)-2-pyrrolidone.
Other ethylenically unsaturated and copolymerizable monomers may be used along with or in place of the (meth)acrylic monomer. For instance, maleic acid or maleic anhydride can be reacted with a reactive amine to provide an amide (half amide or bis-amide) or an imide and may similarly be reacted with various aminoalcohols to provide any of a variety of ester or amide or imide compounds. Alternatively, maleic anhydride itself may be copolymerized or grafted onto a polymer chain to give a succinic anhydride moiety which may be further reacted with an amine or aminoalcohol. Other monomers that may be reacted with amines or aminoalcohols to provide a nitrogen-containing monomer include vinyl substituted nitrogen heterocyclic monomers such as N-vinyl imidazole, N-vinyl pyrrolidinone, and N-vinyl caprolactam; dialkylaminoalkyl(meth)acrylate monomers, in which the alkyl or amino alkyl groups may independently contain 1 to 8 carbon atoms; dialkylaminoalkyl(meth)acrylamide monomers, and teriary alkyl(meth)acrylamides such as t-butyl acrylamide. Other monomers include piperazine N-alkylmethacrylamide, morpholine N-alkylacrylamide, N-2-aminoethyl-N′-hydroxyethyl methacrylamide, and N-2-aminoethyl-N′-pyridinyl methacylamide. Furthermore, the monomer composition may comprise other monomers such as styrene compounds. These include styrene, substituted styrenes having an alkyl substituent in the side chain, such as alpha-methylstyrene and alpha-ethylstyrene, substituted styrenes having an alkyl substituent on the ring, such as vinyltoluene and p-methylstyrene, halogenated styrenes, such as monochlorostyrenes, dichlorostyrenes, tribrotnostyrenes and tetrabromostyrenes.
The amount of the nitrogen-containing monomer may be an amount suitable to provide at least 0.4 percent by weight of nitrogen to the dispersant viscosity modifier or alternatively 0.4 to 2 percent or to 1.5 percent or to 1.2 percent or to 1.0 percent, or alternatively 0.5 to 0.8 percent. The amount of nitrogen-containing monomer required to deliver this amount of nitrogen to the polymer will depend, of course, on the particular monomer and its nitrogen content. For example, the monomer dimethylaminopropyl methacrylamide, having two nitrogens, is itself about 16.5 percent by weight nitrogen. Suitable amounts of such monomers generally within the copolymer may thus be 1 to 10 percent by weight, or 2.5 to 6 percent or 3 to 5 percent or about 4 percent.
The dispersant viscosity modifier may be prepared by several different processes. In one embodiment, the nitrogen-containing copolymer is obtained by reacting, together, (meth)acrylate ester monomers and the nitrogen-containing monomer. In another embodiment, the nitrogen-containing monomer is grafted onto a preformed (meth)acrylate copolymer backbone, or maleic anhydride may be grafted and subsequently reacted with amine. In yet another embodiment, the polymer can be prepared by reacting a suitable amine with a (meth)acrylate copolymer, liberating the alcohol functionality from a portion of the ester groups.
The dispersant viscosity modifier may be prepared in an organic diluent, and specific amounts and types of diluent can affect the low temperature viscosity properties of lubricants containing them.
The molecular weight (number average molecular weight, M_n) of the dispersant viscosity modifier may be 10,000 to 300,000, or 20,000 to 150,000, or 30,000 to 100,000.
The amount of the dispersant viscosity modifier employed in final lubricating compositions may be 0.5 to about 10 weight percent, or 0.6 to 5% or 0.75 to 4.0% or 1 to 3.5% or 1.5 to 3.35%. In a concentrate, the amount of the dispersant viscosity modifier will be correspondingly greater, e.g., 2 to 50 or 5 to 45 or 10 to 35 percent by weight.
Another component of the present invention is a succinimide dispersant prepared by a certain method, sometimes referred to as “direct alkylation.” Succinimide dispersants generally are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical alkenyl succinimides have a variety of chemical structures including typically
where each R¹is independently an alkyl group, frequently a polyisobutyl group with a molecular weight of 500-5000, and R²are alkylene groups, commonly ethylene (C₂H₄) groups. Such molecules are commonly derived from reaction of an alkenyl acylating agent with a polyamine, and a wide variety of linkages between the two moieties is possible beside the simple imide structure shown above, including a variety of amides and quaternary ammonium salts. Also, a variety of modes of linkage of the R¹groups onto the imide structure are possible, including various cyclic linkages. Succinimide dispersants are more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892.
The succinimide dispersants of the present invention are prepared from hydrocarbyl-substituted succinic acylating agents which are in turn prepared by the so-called “direct alkylation” or “thermal” route, as contrasted with the so-called “chlorine” route. These routes differ in the method by which a polyalkylene (typically polyisobutylene, but also copolymers including ethylene copolymer) substituent is prepared and by which it is affixed to a maleic, that is, succinic acid or anhydride moiety. In an example of preparing a substrate for a conventional or “chlorine” process, isobutylene is polymerized in the presence of AlCl3 to produce a mixture of polymers comprising predominantly trisubstituted olefin (III) and tetrasubstituted olefin (IV) end groups, with only a very small amount (for instance, less than 20 percent) of chains containing a terminal vinylidene group (I). In contrast, for preparation of a substrate for a “chlorine-free” or “thermal” or “direct alkylation” process, isobutylene is polymerized in the presence of BF3 catalyst to produce a mixture of polymers comprising predominantly (for instance, at least 70 percent) terminal vinylidene groups, with smaller amounts of tetrasubstituted end groups and other structures. A thermal process for preparing polyisobutene-substituted maleic anhydride is described in European patent publication EP 0 355 895 A2. The intermediate polyisobutene materials from a non-chlorine process, sometimes referred to as “high vinylidene PIB,” are also described in U.S. Pat. No. 6,165,235, Table 1 of which is summarized below:

TABLE 1

	(a) Typical
PIB	Percent in	(b) Typical Percent in
Terminal Groups	Conventional PIB	High Vinylidene PIB

	4-5%	50-90%

	0-2%	6-35%

	63-67% tri-substituted	absent or minor

	22-28% tetrasubstituted IV and IVA	1-15%



	5-8%	0-4%

OTHER	0-10%

Note Structure I may also be present in high-vinylidene PIB at 70-90%. In other embodiments, the invention may usefully use polyisobutylene containing at least 70%, e.g., 70 to 90%, of structures I and II, combined.

Conventional polyisobutylene reacts with maleic anhydride in the presence of a “catalytic” amount, that is, a “promoting” amount (or typically a molar amount) of chlorine by a series of chlorination, dehydrochlorination, and Diets-Alder reactions, more fully described in U.S. Pat. No. 6,165,235, to provide a significant amount of di-succinated polymeric material which is believed to have predominantly the general structure (VI):
where R is —H or —CH₃and PIB represents a polyisobutene residue after reaction. A certain amount of mono-reacted cyclic material can also be present, as shown:
and, in one instance, the hydrocarbyl-substituted succinic anhydride of (a) contains on average 1.1 or 1.3 to 1.8 succinic anhydride moieties per hydrocarbyl group. It is also believed that a minor amount (e.g., up to 7 or 15 or 18 percent, e.g., 7 to 15 percent) of the product may contain a succinic anhydride moiety attached to the hydrocarbyl group by one sort or another of non-cyclic linkage.
In contrast, high vinylidene polyisobutylene which is typically used in the present invention is believed to react with maleic anhydride in the absence of chlorine by a series of thermal “ene” reactions to produce a mixture of mono- and di-succininated polymeric material, the latter believed to have predominantly the general structure (VII):
the double bond being located at either position about the central carbon atom. Preparation of Acylating Agents from Polyisobutylene Made from a BF₃Process and their reaction with amines is disclosed in U.S. Pat. No. 4,152,499. Similar adducts can be made using polymers other than polyisobutylene; for instance U.S. Pat. No. 5,275,747 discloses derivatized ethylene alpha-olefin polymers with terminal ethenylidene unsaturation which can be substituted with mono- or dicarboxylic acid producing moieties. These materials from the direct alkylation or thermal process may also contain a small amount of materials with cyclic structure. The subsequently formed dispersant may contain at least one succinic moiety which is attached to the hydrocarbyl substituent through a non-cyclic linkage.
The two types of products, described above are presented in this text both in terms of their structure and in terms of their method of manufacture (chlorine versus non-chlorine or thermal or direct alkylation process) for the purpose of completeness and clarity in description, and because it to be understood that further investigation may show that the structures depicted may prove to be incomplete or even to some extent incorrect. Nevertheless it is important to recognize that the materials prepared by the chlorine process are different from those prepared by the non-chlorine route, and these differences, whatever they may ultimately prove to be, are important in the definition of the materials suitable for use in the present invention. Applicants do not intend to be bound by any theoretical explanations.
The hydrocarbyl substituents on the succinic anhydride component should normally be of sufficient length to provide a desired degree of solubility in a lubricating oil. Such substituent will typically have a molecular weight of at least 300, at least 800, or at least 1200, Typical upper limits to the molecular weight may be determined by considerations of solubility, cost, or other practical considerations, and may be up to 5000 or up to 2500. Thus, for instance, the hydrocarbyl substituents can have a molecular weight of 300 to 5000 or 800 to 2500.
The hydrocarbyl-substituted succinic anhydride (or reactive equivalent thereof) is condensed an amine (or a mixture of amines) to form the succinimide dispersant. Amines which can be used in preparing such dispersants include polyamines, such as aliphatic, cycloaliphatic, heterocyclic or aromatic polyamines. Examples of the polyamines include alkylene polyamines, hydroxy containing polyamines, arylpolyamines, and heterocyclic polyamines.
Alkylene polyamines are represented by the formula
wherein n typically has an average value 1, or 2 to 10, or to 7, or to 5, and the “Alkylene” group has 1, or 2 to 10, or to 6, or to 4 carbon atoms. Each R₅is independently hydrogen, or an aliphatic or hydroxy-substituted aliphatic group of up to 30 carbon atoms. Such alkylenepolyamines include polymethylenepolyamines, ethylenepolyamines, butylenepolyamines, propylenepolyamines, and pentylenepolyamines. The higher homologs and related heterocyclic amines such as piperazines and N-aminoalkyl-substituted piperazines are also included. Specific examples of such polyamines are ethylenediamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tris-(2-aminoethyl)amine, propylenediamine, trimethylenediamine, tripropylenetetramine, tetraethylenepentamine (TEPA), hexaethyleneheptamine, and pentaethylenehexamine. Higher homologs obtained by condensing two or more of the above-noted alkylene amines are similarly useful as are mixtures of two or more of the aforedescribed polyamines. Such polyamines are described in detail under the heading Ethylene Amines in Kirk Othmer's “Encyclopedia of Chemical Technology”, 2d Edition, Vol. 7, pages 22-37, Interscience Publishers, New York (1965). Other useful types of polyamine mixtures are those resulting from stripping of the above-described polyamine mixtures to leave as residue what is often termed polyamine bottoms or, more specifically, polyethyleneamine bottoms.
Another useful polyamine is a condensation reaction between a hydroxy compound and a polyamine reactant containing at least one primary or secondary amino group, as. described in U.S. Pat. No. 5,053,152 and PCT publication WO86/05501.
The dispersants described herein may be post-treated by reaction with any of a variety of agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids such as terephthalic acid, hydrocarbon-substituted succinic anhydrides, nitrites, epoxides, boron compounds, and phosphorus compounds. References detailing such treatment are listed in U.S. Pat. No. 4,654,403. In particular, borated dispersants may be prepared by reacting the dispersant with a boron compound such as boric acid or an alkali or mixed alkali metal and alkaline earth metal borate. These metal borates are generally a hydrated particulate metal borate which are known in the art. Alkali metal borates include mixed alkali and alkaline metal borates. These metal borates are available commercially. The boron content of the succinimide dispersant, if borated, may be 0.1 to about 1 weight percent or 0.2 to 0.6 or to 0.5 weight percent.
The nitrogen content of the dispersant may be 1 to 10 percent by weight, or 1 to 5%, or 1.5 to 3%, or 3 to 8%, or 5 to 6% (on an active chemical or diluent-free basis). The dispersant may have a total base number (TBN) of 5 to 180 or 10 to 170 or 15 to 150 or 40 to 130 or 60 to 120, again, on an active chemical basis (factoring out the presence of any diluent).
The amount of the dispersant in compositions of the present invention may be 0.1 to 10 weight percent, or 0.5 to 7% or 1 to 5% or 2 to 3%. These amounts are particularly suitable for fully formulated lubricants. In concentrates, the amounts may be correspondingly greater, e.g., 5 to 70 or 10 to 50 or 15 to 35 or 20 to 30 percent by weight.
Other components may also be present in the composition, including those components that are commonly present in lubricants including lubricants for transmissions. Suitable materials include antioxidants (such as dialkyl diarylamines, sulfur compounds such as hydroxyalkyl alkyl sulfides (e.g., 1-(tert-dodecylthio)-2-propanol), and hindered phenols including hindered phenolic esters such as those represented by the formula:
wherein R¹¹is a straight chain or branched chain alkyl group containing 2 to 22 carbon atoms, e.g., 2 to 8, 2 to 6, or 4 to 8 carbon such as 4 or 8 carbon atoms. R¹¹may be desirably a 2-ethylhexyl group or an n-butyl group.
The compositions of the present invention may also include at least one phosphorus acid, phosphorus acid salt, phosphorus acid ester or derivative thereof, including sulfur-containing analogs thereof. Suitable amounts include 0.002-1.0 weight percent. The phosphorus acids, salts, esters or derivative include phosphoric acid, phosphorous acid, phosphorus acid esters and salts thereof, phosphites, phosphorus-containing amides, phosphorus-containing carboxylic acids or esters, phosphorus-containing ethers, and mixtures thereof.
In one embodiment, the phosphorus acid, ester or derivative can be an organic or inorganic phosphorus acid, phosphorus acid ester, phosphorus acid salt, or derivative thereof. The phosphorus acids include the phosphoric, phosphonic, phosphinic, and thiophosphoric acids including dithiophosphoric acid as well as the monothiophosphoric, thiophosphinic and thiophosphonic acids. One group of phosphorus compounds are alkylphosphoric acid mono alkyl primary amine salts as represented by the formula
where R¹, R², R³are alkyl or hydrocarbyl groups or one of R¹and R²can be H. The materials can be a 1:1 mixture of dialkyl and monoalkyl phosphoric acid esters. Compounds of this type are described in U.S. Pat. No. 5,354,484, Other suitable materials include phosphates and phosphites, e.g., dialkyl hydrogen phosphites such as dibutyl hydrogen phosphite or mixed di(C16 alkyl/C18 alkenyl)hydrogen phosphonates, i.e., dialkyl hydrogen phosphonates such as dilauryl hydrogen phosphonate. Such materials may be present in amounts of 0.01 to 2 percent by weight, or 0.02 to 1.0% or 0.05 to 0.5%.
Eighty-five percent phosphoric acid is a suitable material for addition to the fully-formulated compositions. The phosphoric acid may be added as such, if desired, or may be pre-reacted with some other component of the composition. It may be included at a level of 0.01-0.3 weight percent based on the weight of the composition, or alternatively 0.02 to 0.25% or 0.03 to 0.2%, or to 0.1 percent. The total amount of phosphorus in the lubricant composition, from all sources, is, in certain embodiments, 0.005 to 0, 5 or 0.01 to 0.2 weight percent.
In certain embodiments the lubricant may contain multiple species of phosphorus compounds, for instance, an inorganic phosphorus acid such as phosphoric acid and a phosphorus ester such as dibutyl hydrogen phosphite or dilauryl hydrogen phosphite.
The formulations may also contain any of a variety of friction modifiers. These may include secondary and tertiary amines as described in U.S. application 2006/0172899, see in particular paragraph 0010 and the examples in Table II thereof. These amines are represented by the formula R¹R²NR³, where R¹and R²are each independently an alkyl group of at least 6 carbon atoms and R³is a hydroxyl-containing alkyl group, a hydroxyl-containing alkoxyalkyl group, an amine-containing alkyl group, a hydrocarbyl group, or hydrogen, provided that when R³is H, then at least one of R¹and R²is an alkyl group of 8 to 16 carbon atoms. Also included are friction modifiers containing at least two hydrocarbon groups, derived from the reaction of a carboxylic acid with an amino alcohol, as disclosed in WO 04/007652, and also friction modifiers derived from the reaction of a carboxylic acid or reactive equivalent thereof with an aminoalcohol, wherein the friction modifier contains at least two hydrocarbyl groups of at least 6 carbon atoms, as disclosed in U.S. application US-2005-0250655. Other friction modifiers which are known and commercially available include fatty phosphites, fatty acid amides, fatty epoxides, borated fatty epoxides, other fatty amines, glycerol esters including glycerol partial esters, borated glycerol esters and partial esters, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, sulfurized olefins, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines, metal salts of alkyl salicylates, amine salts of alkylphosphoric acids, and mixtures thereof. Specific examples of many of these materials are set forth in the above-mentioned US application 2006/0172899, see paragraphs 0058 through 0068.
In certain embodiments, the lubricant composition may contain a detergent. Detergents are typically neutral or basic (overbased) salts of acidic materials. Overbased materials are generally single phase, homogeneous Newtonian systems characterized by a metal content in excess of that which would be present for neutralization according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. The overbased materials are prepared by reacting an acidic material (typically an inorganic acid or lower carboxylic acid, preferably carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (e.g., mineral oil, naphtha, toluene, xylene) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter such as a phenol or alcohol. The acidic organic material will normally have a sufficient number of carbon atoms to provide a degree of solubility in oil. The amount of excess metal is commonly expressed in terms of metal ratio. The term “metal ratio” is the ratio of the total equivalents of the metal to the equivalents of the acidic organic compound. A neutral metal salt has a metal ratio of one. A salt having 4.5 times as much metal as present in a neutral salt will have metal excess of 3.5 equivalents, or a ratio of 4.5.
Such overbased materials are well known to those skilled in the art. Patents describing techniques for making basic salts of sulfonic acids, carboxylic acids, phenols, phosphoric acids, and mixtures of any two or more of these include U.S. Pat. Nos. 2,501,731; 2,616,905; 2,616,911; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and 3,629,109. Other overbased materials are salixarate detergents, which include overbased materials prepared from salicylic acid (which may be unsubstituted) with a hydrocarbyl-substituted phenol, such entities being linked through CH₂or other alkylene bridges. It is believed that the salixarate derivatives have a predominantly linear although both linear and macrocyclic structures are encompassed by the term “salixarate,” Salixarate derivatives and methods of their preparation are described in greater detail in U.S. Pat. No. 6,200,936 and PCT Publication WO 01/56968.
The lubricants of the present invention may also contain pour point depressants. These are known materials and include those based on poly(alkyl(meth)acrylates) where the alkyl group may be long chain groups such as lauryl or stearyl; maleic anhydride/styrene copolymers esterified with aliphatic alcohols of, e.g., 13-16 carbons and optionally further reacted with an amine and optionally including other monomers such methyl methacrylate; alkylated aromatic compounds such as alkylated naphthalene; and copolymers of vinyl acetate with esters such as C18-22 fumarates. The amount of pour point depressant may be 0.1 to 0.5 or 0.2 to 0.4 percent by weight.
Also included can be known materials such as corrosion inhibitors (e.g., triazoles such as tolyltriazole, or thiadiazoles such as dimercaptothiadiazoles and derivatives thereof), dyes, fluidizing agents, odor masking agents, and antifoam agents. Organic borate esters and organic borate salts may also be included. Seal swell agents such as sulfolanes (e.g., thiophene, 3-(decyloxy) tetrahydro-1,1-dioxide) or phthalate esters (e.g., dihexyl phthalates) may be also present, typically in amounts of 0.1% or more, e.g., 0.1 to 2.5 or 0.2 to 2.0 percent.
As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:
hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form a ring);
substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);
hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.
It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. For instance, metal ions (of, e.g., a detergent) can migrate to other acidic or anionic sites of other molecules. The products formed thereby, including the products formed upon employing the composition of the present invention in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present invention; the present invention encompasses the composition prepared by admixing the components described above.

EXAMPLES

Lubricant formulations of a type generally suitable for use in automatic transmission fluids are prepared with certain variations as detailed below. Each formulation is prepared in a mixture of API Group II and Group III oils and each contains 250 ppm red dye and 27-28 ppm commercial foam inhibitor. The formulations also contain 1.4 weight percent nitrogen- and sulfur-containing antioxidants, 0.2 wt. % nitrogen-containing friction modifiers, 0.15 wt. % (meth)acrylic polymer pour point depressant, 0.11 wt. % dialkyl hydrogen phosphite, 0.1 wt. % phosphoric acid (85%), and 0.02 wt. % corrosion inhibitor. Additional components are shown in the following Table:


Example	1	2*	3*	4*	5	6*	7	8*	9*

“DA” dispt^a	2.07			2.07	3.08	3.08	2.07
“Cl” dispt^b		2.44	2.44					2.44	2.44
DVM low N^c			1.65	1.65		1.65			1.65
DVM high N^d	1.65	1.65			1.65		1.65	1.65
Test results
Oxidation test: %	−3.9	17	30.3	7.7	−14.8	−4.2	—	—	—
viscosity change
GM oxidation test	—	—	—	—	—	—	Pass	near	Fail
overall								Fail
TAN increase	—	—	—	—	—	—	2.8	3.1	2.6
Sludge, clutch	—	—	—	—	—	—	8.6	7.5	7.7
housing
Sludge, clutch	—	—	—	—	—	—	8.8	7.5	6.9
piston
Cu ppm in	—	—	—	—	—	—	139	187	273
drain, end of test

^aA borated succinimide dispersant wherein the precursor alkylsuccinic anhydride is prepared by a direct alkylation (chlorine-free, thermal) route
^bA borated succinimide dispersant wherein the precursor alkylsuccinic anhydride is prepared by a chlorine-promoted route
^cA dispersant viscosity modifier based on a polymethacrylate copolymer containing 2 wt. % 3-dimethylaminopropyl methacrylamide comonomer (0.33% nitrogen in the polymer)
^dA dispersant viscosity modifier based on a polymethacrylate copolymer containing 4% 3-dimethylaminopropyl methacrylamide comonomer (0.66% nitrogen in the polymer). M_n= 21,300; M_w138,000.
*A comparative example
— Indicates test not run

Certain of the formulations are subject to an oxidation test to evaluate undesirable increase in viscosity of lubricants due to oxidative deterioration. The test comprises treating a sample of the oil with 200 ppm copper and 250 ppm iron and heating under air purging for about 500 hours at 157° C. The viscosity (kinematic viscosity, 100° C.) of the sample after the oxidation treatment is compare with that before treatment, and the results are expressed in terms of percent change in viscosity. The results (example 1 versus comparative examples 2, 3, and 4; example 5 versus comparative example 6) show no increase in viscosity and in fact a modest reduction in viscosity.
Certain of the formulations are subjected to a second oxidation test (“GM oxidation test”) which is a part of the specification for fluids for certain General Motors automatic transmissions, The test utilizes a motored 4L60E automatic transmission run at steady state conditions (1755 RPM and 163° C.) for 450 hours. At end of test samples are drawn from the transmission and sent for analysis. This analysis includes viscosity, total acid number (TAN), and elemental analysis. At the end of the test the transmission is also disassembled and the forward clutch piston and housing are both rated for sludge build up on a scale of 1 to 10, with higher numbers representing superior performance. All of these parameters give an indication on the level of oxidation occurring in the automatic transmission fluid.
Each of the documents referred to above is incorporated herein by reference. The mention of any document is not an admission that such document qualifies as prior art or constitutes the general knowledge of the skilled person in any jurisdiction. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word “about.” Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention can be used together with ranges or amounts for any of the other elements. As used herein, the expression “consisting essentially of” permits the inclusion of substances that do not materially affect the basic and novel characteristics of the composition under consideration.

Claims

1. A lubricant composition comprising:

(a) an oil of lubricating viscosity;

(b) a dispersant viscosity modifier comprising a poly(meth)acrylate copolymer containing nitrogen derived from a nitrogen-containing monomer in an amount to provide at least about 0.4 percent by weight nitrogen to said dispersant viscosity modifier; and

(c) a succinimide dispersant prepared from reaction of an amine with a hydrocarbyl-substituted succinic acylating agent prepared by reaction of a polyalkene, at least about 70 percent of the chains thereof containing a terminal vinylidene end group, with maleic anhydride in the substantial absence of chlorine.

2. The composition of claim 1 further comprising (d) a phosphorus acid.

3. The composition of claim 1 wherein the dispersant viscosity modifier comprises about 0.4 to about 1.2 weight percent nitrogen atoms.

4. The composition of claim 1 wherein the dispersant viscosity modifier contains about 2.5 to about 6 percent by weight units derived from said nitrogen-containing monomer

5. The composition of claim 1 wherein the nitrogen-containing monomer comprises 3-dimethylaminopropyl methacrylamide, N-vinylpyrrolidone, or dimethylaminoethyl methacrylate.

6. The composition of claim 1 wherein the dispersant viscosity modifier is a copolymer derived from monomers comprising C₆-C₁₈alkyl methacrylates and 3-dimethylaminopropyl methacrylate.

7. The composition of claim 6 wherein the C₆-C₁₈alkyl methacrylates comprise 2-ethylhexyl methacrylate.

8. The composition of claim 6 wherein monomers of the dispersant viscosity modifier further comprise a C₁-C₄alkyl methacrylate.

9. The composition of claim 1 wherein the amount of the dispersant viscosity modifier is about 0.5 to about 10 weight percent.

10. The composition of claim 1 wherein the succinimide dispersant contains at least one succinic moiety which is attached to the hydrocarbyl substituent through a non-cyclic linkage.

11. The composition of claim 1 wherein the hydrocarbyl substituent of the succinimide dispersant is a polyisobutene substituent.

12. The composition of claim 1 wherein the amine portion of the succinimide dispersant comprises a poly(alkyleneamine).

13. The composition of claim 1 wherein the succinimide dispersant is borated.

14. The composition of claim 13 wherein the boron content of the succinimide dispersant is about 0.1 to about 1 weight percent.

15. The composition of claim 1 wherein the succinimide dispersant is further treated with terephthalic acid.

16. The composition of claim 1 wherein the nitrogen content of the succinimide dispersant is about 0.8 to about 2.0 weight percent.

17. The composition of claim 1 wherein the succinimide dispersant is present in an amount of about 0.1 to about 10 weight percent.

18. A composition prepared by admixing the components of claim 1.

19. A method of lubricating a transmission, a gear box, a transfer case, or a chain, comprising supplying thereto the lubricant composition of claim 1.