Process for producing ethylene alpha-olefin polymer substituted mono- and dicarboxylic acid dispersant additives

This invention relates to a process for preparing improved oil soluble dispersant additives useful in oleaginous compositions, including fuels and lubricating oil compositions.

BACKGROUND OF THE INVENTION

Ashless nitrogen and ester containing lubricating oil dispersants have been widely used by the industry. Typically, these dispersants are prepared from a long chain hydrocarbon polymer by reacting the polymer with maleic anhydride to form the corresponding polymer which is substituted with succinic anhydride groups. Polyisobutylene has been widely used as the polymer of choice, chiefly because it is readily available by cationic polymerization from butene streams (e.g., using AlCl₃ catalysts). Such polyisobutylenes generally contain residual unsaturation in amounts of about one ethylenic double bond per polymer chain, positioned along the chain.

The polyisobutylene polymers (PIB) employed in most conventional dispersants are based on a hydrocarbon chain of a number average molecular weight (<maths id="math0001" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0001.tif" /></maths>_n) of from about 900 to about 2500. PIB having a <maths id="math0002" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0002.tif" /></maths>_n of less than about 300 gives rather poor performance results when employed in dispersants because the molecular weight is insufficient to keep the dispersant molecule fully solubilized in lubricating oils. On the other hand, high molecular weight PIB (<maths id="math0003" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0003.tif" /></maths>_n &gt;3000) becomes so viscous that conventional industrial practices are incapable of handling this product in many operations. This problem becomes much more severe as the PIB molecular weight increases to 5000 or 10,000.

Increased amounts of terminal ethylenic unsaturation in polyisobutylene (so-called "reactive polyisobutylene") has been achieved by BF₃ catalyzed polymerization of isobutylene Exemplary of references disclosing these polymers is U.S. Patent 4, 152, 499. However, such reactive polyisobutylene materials can still contain substantial amounts of unsaturation elsewhere along the chain. Further, it is difficult to produce such reactive polyisobutylene polymers at molecular weights of greater than 2,000, and, even so, the reactive polyisobutylenes themselves still suffer the above-noted viscosity increase disadvantages as molecular weights are increased. EP-A-208560 discloses polymers substituted by reaction with maleic anhydride, which polymers may include ethylene-propylene copolymers and which are described as having approximately one double bond per polymer chain.

Other polymers, such as ethylene-propylene co-polymers and terpolymers containing non-conjugated dienes, have been disclosed as suitable polymers for the preparation of ashless nitrogen and ester dispersants.

U.S. Patent 4, 234, 435, for example, discloses dispersants prepared from polyalkenes, Mn of 1,300 to about 5,000. The polyalkene can comprise homopolymers or interpolymers of C₂ to C₁₆ terminal olefins, of which ethylene-propylene copolymers are said to be examples, with specific reference to a copolymer of 80% ethylene and 20% propylene.

However, ethylene-alpha-olefin copolymers of the above molecular weights could be produced using Ziegler-Natta catalysts only in combination with H₂ as molecular weight control in order to terminate the growing copolymer chains within this molecular weight range. Without the use of H₂ or other conventional, so-called "chain stoppers", the copolymers produced with Ziegler-Natta catalysts would tend to have molecular weights greatly in excess of the above range. (Such higher copolymers, for example, are widely employed in ungrafted form as viscosity index improvers, and when grafted with nitrogen-containing groups, as described below, are conventionally employed as dispersant-viscosity index improver polymers.) The use of H₂ as a chain stopper has the disadvantage of causing the saturation of the olefinic double bond content of the copolymer. Thus, while lower molecular weight copolymers were theoretically possible to prepare, their low unsaturation content (and the accompanying low graft copolymer yields) would have made their further functionalization by a thermal "ene" reaction, e.g., with dicarboxylic acid moieties in preparing dispersants, highly unattractive.

High molecular weight ethylene-propylene polymers and ethylene-propylene-diene terpolymers, having viscosity average molecular weights of from about 20,000 to 300,000, are generally produced employing Ziegler catalysts, generally VCl₄ or VOCl₃ with a halide source, such as organoaluminum halides and/or hydrogen halides. Such high molecular weight EP and EPDM polymers find use as viscosity index improvers. See, e.g., U.S. Patents 3,563,964; 3,697,429; 4,306,041; 4,540,753; 4,575,574; and 4,666,619.

The concept of derivatizing V.I. improving high molecular weight ethylene copolymers, with acid moieties such as maleic anhydride, followed by reaction with an amine, to form a V.I.-dispersant oil additive is known in the art as indicated by the following patents.

U.S. Patent 3,316,177 teaches ethylene copolymers of at least 50,000, such as ethylene-propylene, or ethylene-propylene-diene, which are heated to elevated temperatures in the presence of oxygen so as to oxidize the polymer and cause its reaction with maleic anhydride which is present during the oxidation. The resulting polymer can then be reacted with alkylene polyamines.

U.S. Patent 3,326,804 teaches reacting ethylene copolymers with oxygen or ozone, to form a hydroperoxidized polymer, which is grafted with maleic anhydride followed by reaction with polyalkylene polyamines. Preferred are ethylene-propylene copolymers, having <maths id="math0004" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0004.tif" /></maths>_v from 100,000 to 500,000, prepared by Ziegler type catalysts.

U.S. Patent 4,160,739 teaches an ethylene copolymer (<maths id="math0005" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0005.tif" /></maths>_v = 10,000 to 200,000) which is grafted, using a free radical technique, with alternating maleic anhydride and a second polymerizable monomer such as methacrylic acid, which materials are reacted with an amine having a single primary, or a single secondary, amine group.

U.S. Patent 4,161,452 relates to graft copolymers wherein the backbone polymer is a polymeric hydrocarbon such as EP copolymer or EPDM (<maths id="math0006" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0006.tif" /></maths>_v = 10,000 to 200,000) and the grafted units are the residues of an addition copolymerizable monomer system comprising, e.g., maleic anhydride, and at least one other addition monomer.

U.S. Patent 4,171,273 reacts an ethylene copolymer (<maths id="math0007" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0007.tif" /></maths>_v = 10,000 to 100,000) with maleic anhydride in the presence of a free radical initiator and then with mixtures of C₄ to C₁₂ n-alcohol and amine such as N-aminopropylmorpholine or dimethylamino propyl amine to form a V.I.-dispersant-pour depressant additive.

U.S. Patent 4,517,104 relates to EP and EPDM viscosity index improver-dispersant additives prepared from EP polymer (<maths id="math0008" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0008.tif" /></maths>_n = 5000 to 500,000), by maleic anhydride grafting and reaction with polyamines.

The following references include disclosures of EP/EPDM polymers of <maths id="math0009" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0009.tif" /></maths>_n of 700/500,000, also prepared by conventional Ziegler catalysts.

U.S. Patent 4,089,794 teaches grafting the ethylene copolymer (<maths id="math0010" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0010.tif" /></maths>_n = 700 to 500,000) with maleic anhydride using peroxide in a lubricating oil solution, wherein the grafting is preferably carried out under nitrogen, followed by reaction with polyamine.

U.S. Patent 4,137,185 teaches reacting C₁ to C₃₀ monocarboxylic acid anhydrides, and dicarboxylic anhydrides, such as acetic anhydride, succinic anhydride, etc., with an ethylene copolymer (<maths id="math0011" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0011.tif" /></maths>_n = 700 to 500,000) reacted with maleic anhydride and a polyalkylene polyamine to inhibit cross linking and viscosity increase due to further reaction of any primary amine groups which were initially unreacted.

U.S. Patent 4,144,181 is similar to 4,137,185 in that it teaches using a sulfonic acid to inactivate the remaining primary amine groups when a maleic anhydride grafted ethylene-propylene copolymer (<maths id="math0012" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0012.tif" /></maths>_n = 700 to 500,000) is reacted with a polyamine.

U.S. Patent 4,219,432 teaches maleic anhydride grafted ethylene copolymer (<maths id="math0013" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0013.tif" /></maths>_n = 700 to 500,000) reacted with a mixture of an amine having only one primary group together with a second amine having two or more primary groups.

Related disclosures of maleic anhydride grafted, aminated ethylene-propylene polymer viscosity improver-dispersant additives useful in lubricating oil compositions are contained in U.S. Patents 4,507,515; 4,557,847; 4,632,769; 4,693,838; and 4,707,285.

U.S. Patent 4,668,834 to Uniroyal Chemical discloses preparation (via certain metallocene and alumoxane catalyst systems) and composition of ethylene-alpha olefin copolymers and terpolymers having vinylidene-type terminal unsaturation, which are disclosed to be useful as intermediates in epoxy-grafted encapsulation compositions.

U.S. Patent 4,704,491 to Mitsui Petrochemical relates to liquid ethylene alpha-olefin random copolymers, useful when hydrogenated as synthetic lubricant oil, characterized <u>inter</u><u>alia</u> by having 10-85 mol.% ethylene units, 15-90 mol.% alpha-olefin units, <maths id="math0014" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0014.tif" /></maths>_n of from 300 to 10,000 and a <maths id="math0015" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0015.tif" /></maths>_w/<maths id="math0016" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0016.tif" /></maths>_n of not more than 2.5. The patent also indicates that the liquid copolymer can be easily modified since it has a double bond capable of reacting with maleic anhydride, etc., at the molecular chain ends.

Japanese Published Patent Application 87-129,303A of Mitsui Petrochemical relates to narrow molecular weight distribution (<maths id="math0017" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0017.tif" /></maths>_w/<maths id="math0018" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0018.tif" /></maths>_n &lt;2.5 ) ethylene alpha-olefin copolymer waxes containing 85-99 mol% ethylene, which are disclosed to be used for dispersing agents, modifiers or materials to produce toners. The copolymers (having crystallinity of from 5-85%) are prepared in the presence of a catalyst system comprising Zr compounds having at least one cycloalkadienyl group and alumoxane.

European Patent 128,046 discloses (co)polyolefin reactor blends of polyethylene and ethylene higher alpha-olefin copolymers prepared by employing described dual-metallocene/alumoxane catalyst systems.

European Patent Publication 129,368 discloses metallocene/alumoxane catalysts useful for the preparation of ethylene homopolymer and ethylene higher alpha-olefin copolymers.

European Patent Application Publication 257,696 A1 relates to a process for dimerizing alpha-olefins using a catalyst comprising certain metallocene/alumoxane systems.

European Patent Publication 305,022-A1 to Mitsui Petrochemical relates to certain synthetic hydrocarbon lubricating oil compositions containing a load-withstanding additive and a liquid ethylene alpha-olefin random copolymer modified by graft copolymerization with an unsaturated carboxylic acid or derivative thereof (eg, maleic anhydride). The ethylene alpha-olefin copolymers (Mn of 300 to 12,000) are obtained using Ziegler catalysts (eg, catalyst formed from soluble V compound and an organo aluminium compound), are grafted in the presence of a free radical initiator.

PCT Published Patent Application WO 88/01626 relates to transition metal compound/alumoxane catalysts for polymerizing alpha-olefins.

<u>SUMMARY OF THE INVENTION</u>

The present invention relates to a low sediment process for producing an additive useful in fuel compositions which comprises contacting: <ul id="ul0001" list-style="none"><li>(a) an ethylene alpha-olefin polymer comprising monomer units derived from ethylene and at least one alpha-olefin of the formula H₂C=CHT¹ wherein T¹ is an alkyl group of from 1 to 18 carbon atoms, said polymer having a number average molecular weight of from 11,192 to 20,000 and wherein an average of at least 30% of said polymer chains contain terminal ethenylidene unsaturation; and</li><li>(b) at least one monounsaturated carboxylic reactant selected from the group consisting of (i) monounsaturated C₄ to C₁₀ dicarboxylic acids wherein (a) the carbonyl groups are attached to adjacent carbon atoms and (b) at least one of said adjacent carbon atoms are part of said mono unsaturation, (ii) anhydride or C₁ to C₅ alcohol derived mono-or di-ester derivatives of (i); (iii) monounsaturated C₃ to C₁₀ monocarboxylic acids wherein the carbon-carbon double bond is allylic to the carboxy group; and (iv) C₁ to C₅ alcohol derived mono-ester derivatives of (iii) under conditions and for a time sufficient to form a low sediment product mixture containing an ethylene alpha-olefin polymer substituted with said carboxylic acid moieties, wherein said product mixture is characterised by a VR value of not greater than 4.1 and by a functionality of at least 0.7.</li></ul>

The monocarboxylic acid and the dicarboxylic acid or anhydride substituted polymers of this invention are useful <u>per se</u> as additives to oleaginous compositions, such as fuels or lubricating oils, and can also be reacted with a nucleophilic reagent, such as amines, alcohols, amino alcohols and metal compounds, to form derivative products which are also useful as additives or lubricating oil additives, eg, as dispersants.

EP-A-353935 describes such interpolymers of 300 to 10,000 number average molecular weight terminally substituted with mono- or dicarboxylic acid producing moieties, and derivatives formed with amines, alcohols, amine alcohols and metal compounds.

The materials prepared by the process of the invention are different from the prior art because of their effectiveness and their ability to provide enhanced lubricating oil dispersancy, as exhibited by their enhanced sludge and varnish control properties. In fuels, the additives serve to minimize the degree of carburetor and fuel injector fouling from deposits. In addition, the additives of this invention possess superior viscometric properties.

The process of this invention permits the preparation of lubricating oil and fuel dispersant additives which are simultaneously characterized by a high active ingredient content (usually at least about 60 wt.%, up to about 95 wt.%) and by advantageous viscosity properties to permit the additives to be readily handled. In addition, the ethylene alpha-olefin polymers substituted by mono- and di-carboxylic acid producing moieties of this invention can be characterized by VR values (as hereinafter defined) of not greater than about 4.1, thereby providing advantageous viscosity modifying properties to the lubricating oils containing them. The present invention can produce such substituted polymers in a highly concentrated form as substantially halogen free materials, thereby reducing the corrositivity processing difficulties and environmental concerns which are associated with halogen-containing lubricating oil additives.

Further, dispersant materials can be prepared from the substituted polymers prepared by the process of this invention to provide fuel and lubricating oil dispersant products having VR' values of not greater than about 4.1 and VR'/VR_r ratios of less than about 1.11 (as such values and ratios are hereinafter defined). Surprisingly, the process of this invention permits the preparation of highly concentrated, substantially halogen-free dispersants from high molecular weight ethylene-alpha-olefin polymers (11,192-20,000) of superior viscosity properties.

DETAILED DESCRIPTION OF THE INVENTION

Preparation of Ethylene Alpha-olefin Polymer

The polymers employed in the process of this invention are polymers of ethylene and at least one alpha-olefin having the formula H₂C=CHR¹ wherein R¹ is straight chain or branched chain alkyl radical comprising 1 to 18 carbon atoms and wherein the polymer contains a high degree of terminal ethenylidene unsaturation. Preferably R¹ in the above formula is alkyl of from 1 to 8 carbon atoms, and more preferably is alkyl of from 1 to 2 carbon atoms. Therefore, useful comonomers with ethylene in this invention include propylene, 1-butene, hexene-1, octene-1, 4-methylpentene-1, decene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1 and mixtures thereof (e.g., mixtures of propylene and 1-butene, and the like).

Exemplary of such polymers are ethylene-propylene copolymers, ethylene-butene-1 copolymers and the like. Preferred polymers are copolymers of ethylene and propylene and ethylene and butene-1.

The molar ethylene content of the polymers employed in this invention is preferably in the range of between about 20 and about 80 percent, and more preferably between about 30 and about 70 percent. When propylene and/or butene-1 are employed as comonomer(s) with ethylene, the ethylene content of such copolymers is most preferably between about 45 and about 65 percent, although higher or lower ethylene contents may be present.

The polymers employed in the process of this invention generally possess a number average molecular weight of from 11,192 to 20,000. The number average molecular weight for such polymers can be determined by several known techniques. A convenient method for such determination is by size exclusion chromatography (also known as 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.

Consequently, such polymers generally possess an intrinsic viscosity (as measured in tetralin at 135°C) of between about 0.025 and about 0.9 dl/g, preferably of between about 0.05 and about 0.5 dl/g, most preferably of between about 0.075 and about 0.4 dl/g.

The polymers employed in this invention preferably exhibit a degree of crystallinity such that, when grafted, they are essentially amorphous.

The polymers employed in this invention are further characterized in that up to about 95% and more of the polymer chains possess terminal ethenylidene-type unsaturation. Thus, one end of such polymers will be of the formula POLY-C(T¹)=CH₂ wherein T¹ is C₁ to C₁₈ alkyl, preferably C₁ to C₈ alkyl, and more preferably C₁ to C₂ alkyl, (e.g., methyl or ethyl) and wherein POLY represents the polymer chain. The chain length of the T¹ alkyl group will vary depending on the comonomer(s) selected for use in the polymerization. A minor amount of the polymer chains can contain terminal ethenyl unsaturation, i.e. POLY-CH=CH₂, and a portion of the polymers can contain internal monounsaturation, e.g. POLY-CH=CH(T¹), wherein T¹ is as defined above.

The polymer employed in this invention comprises polymer chains, at least about 30 percent of which possess terminal ethenylidene unsaturation. Preferably at least about 50 percent, more preferably at least about 60 percent, and most preferably at least about 75 percent (e.g. 75-98%), of such polymer chains exhibit terminal ethenylidene unsaturation. The percentage of polymer chains exhibiting terminal ethyenylidene unsaturation may be determined by FTIR spectroscopic analysis, titration, or C¹³NMR.

The polymer and the composition employed in this invention may be prepared as described in U.S. Patent 4,668,834, in European Patent Publications 128,046 129,368, and 0260999.

The polymers for use in the present invention can be prepared by polymerizing monomer mixtures comprising ethylene in combination with other monomers such as alpha-olefins having from 3 to 20 carbon atoms (and preferably from 3-4 carbon atoms, i.e., propylene, butene-1, and mixtures thereof) in the presence of a catalyst system comprising at least one metallocene (e.g., a cyclopentadienyl-transition metal compound) and an alumoxane compound. The comonomer content can be controlled through the selection of the metallocene catalyst component and by controlling the partial pressure of the various monomers.

The catalysts employed in the production of the reactant polymers are organometallic coordination compounds which are cyclopentadienyl derivatives of a Group 4b metal of the Periodic Table of the Elements (56th Edition of Handbook of Chemistry and Physics, CRC Press [1975]) and include mono, di and tricyclopentadienyls and their derivatives of the transition metals. Particularly desirable are the metallocene of a Group 4b metal such as titanium, zirconium, and hafnium. The alumoxanes employed in forming the reaction product with the metallocenes are themselves the reaction products of an aluminum trialkyl with water.

In general, at least one metallocene compound is employed in the formation of the catalyst. As indicated, supra, metallocene is a metal derivative of a cyclopentadiene. The metallocenes usefully employed in accordance with this invention contain at least one cyclopentadiene ring. The metal is selected from the Group 4b preferably titanium, zirconium, and hafnium, and most preferably hafnium and zirconium. The cyclopentadienyl ring can be unsubstituted or contain one or more substituents (e.g., from 1 to 5 substituents) such as, for example, a hydrocarbyl substituent (e.g., up to 5 C₁ to C₅ hydrocarbyl substituents) or other substituents, e.g. such as, for example, a trialkyl silyl substituent. The metallocene can contain one, two, or three cyclopentadienyl rings; however, two rings are preferred.

Useful metallocenes can be represented by the general formulas:         I.   (Cp)_mMR_nX_q wherein Cp is a cyclopentadienyl ring, M is a Group 4b transition metal, R is a hydrocarbyl group or hydrocarboxy group having from 1 to 20 carbon atoms, X is a halogen, and m is a whole number from 1 to 3, n is a whole number from 0 to 3, and q is a whole number from 0 to 3.         II.   (C₅R'_k)_gR"_s(C₅R'_k)MQ_3-g and         III.   R"_s(C₅R'_k)₂MQ' wherein (C₅R'_k) is a cyclopentadienyl or substituted cyclopentadienyl, each R' is the same or different and is hydrogen or a hydrocarbyl radical such as alkyl, alkenyl, aryl, alkylaryl, or arylalkyl radical containing from 1 to 20 carbon atoms, a silicon containing hydrocarbyl radical, or hydrocarbyl radicals wherein two carbon atoms are joined together to form a C₄-C₆ ring, R" is a C₁-C₄ alkylene radical, a dialkyl germanium or silicon, or a alkyl phosphine or amine radical bridging two (C₅R'_k) rings, Q is a hydrocarbyl radical such as aryl, alkyl, alkenyl, alkylaryl, or aryl alkyl radical having from 1-20 carbon atoms, hydrocarboxy radical having from 1-20 carbon atoms or halogen and can be the same or different from each other, Q' is an alkylidene radical having from 1 to about 20 carbon atoms, s is 0 or 1, g is 0, 1 or 2, s is 0 when g is 0, k is 4 when s is 1, and k is 5 when s is 0, and M is as defined above. Exemplary hydrocarbyl radicals are methyl, ethyl, propyl, butyl, amyl, isoamyl, hexyl, isobutyl, heptyl, octyl, nonyl, decyl, cetyl, 2-ethylhexyl, phenyl and the like. Exemplary silicon containing hydrocarbyl radicals are trimethylsilyl, triethylsilyl and triphenylsilyl. Exemplary halogen atoms include chlorine, bromine, fluorine and iodine and of these halogen atoms, chlorine is preferred. Exemplary hydrocarboxy radicals are methoxy ethoxy, butoxy, amyloxy and the like. Exemplary of the alkylidene radicals is methylidene, ethylidene and propylidene.

Illustrative, but non-limiting examples of the metallocenes represented by formula I are dialkyl metallocenes such as bis(cyclopentadienyl)titanium dimethyl, bis(cyclopentadienyl)titanium diphenyl, bis(cyclopentadienyl)zirconium dimethyl, bis(cyclopentadienyl)zirconium diphenyl, bis(cyclopentadienyl)hafnium dimethyl and diphenyl, bis(cyclopentadienyl)titanium di-neopentyl, bis(cyclopentadienyl)zirconium di-neopentyl, bis(cyclopentadienyl)titanium dibenzyl, bis(cyclopentadienyl)zirconium dibenzyl, bis(cyclopentadienyl)vanadium dimethyl; the mono alkyl metallocenes such as bis(cyclopentadienyl)titanium methyl chloride, bis(cyclopentadienyl)titanium ethyl chloride bis(cyclopentadienyl)titanium phenyl chloride, bis(cyclopentadienyl)zirconium hydrochloride, bis(cyclopentadienyl)zirconium methyl chloride, bis(cyclopentadienyl)zirconium ethyl chloride, bis(cyclopentadienyl)zirconium phenyl chloride, bis(cyclopentadienyl)titanium methyl bromide, bis(cyclopentadienyl)titanium methyl iodide, bis(cyclopentadienyl)titanium ethyl bromide, bis(cyclopentadienyl) titanium ethyl iodide, bis(cyclopentadienyl)titanium phenyl bromide, bis(cyclopentadienyl)titanium phenyl iodide, bis(cyclopentadienyl)zirconium methyl bromide, bis(cyclopentadienyl)zirconium methyl iodide, bis(cyclopentadienyl)zirconium ethyl bromide. bis(cyclopentadienyl)zirconium ethyl iodide, bis(cyclopentadienyl)zirconium phenyl bromide, bis(cyclopentadienyl)zirconium phenyl iodide; the trialkyl metallocenes such as cyclopentadienyltitanium trimethyl, cyclopentadienyl zirconium triphenyl, and cyclopentadienyl zirconium trineopentyl, cyclopentadienylzirconium trimethyl, cyclopentadienylhafnium triphenyl, cyclopentadienylhafnium trineopentyl, and cyclopentadienylhafnium trimethyl.

Illustrative, but non-limiting examples of II and III metallocenes which can be usefully employed are monocyclopentadienyls titanocenes such as, pentamethylcyclopentadienyl titanium trichloride, pentaethylcyclopentadienyl titanium trichloride, bis(pentamethylcyclopentadienyl) titanium diphenyl, the carbene represented by the formula bis(cyclopentadienyl)titanium=CH₂ and derivatives of this reagent such as bis(cyclopentadienyl)Ti=CH₂.Al(CH₃)₃, (Cp₂TiCH₂)₂, <chemistry id="chem0001" num="0001"><img file="EP0441548B1_D0019.tif" /></chemistry><chemistry id="chem0002" num="0002"><img file="EP0441548B1_D0020.tif" /></chemistry> substituted bis(Cp)Ti(IV) compounds such as bis(indenyl)titanium diphenyl or dichloride, bis(methylcyclopentadienyl)titanium diphenyl or dihalides; dialkyl, trialkyl, tetra-alkyl and penta-alkyl cyclopentadienyl titanium compounds such as bis(1,2-dimethylcyclopentadienyl)titanium diphenyl or dichloride, bis(1,2-diethylcyclopentadienyl)titanium diphenyl or dichloride and other dihalide complexes; silicon, phosphine, amine or carbon bridged cyclopentadiene complexes, such as dimethylsilyldicyclopentadienyl titanium diphenyl or dichloride, methyl phosphine dicyclopentadienyl titanium diphenyl or dichloride, methylenedicyclopentadienyl titanium diphenyl or dichloride and other complexes described by formulae II and III.

Illustrative but non-limiting examples of the zirconocenes of Formula II and III which can be usefully employed are, pentamethylcyclopentadienyl zirconium trichloride, pentaethylcyclopentadienyl zirconium trichloride, the alkyl substituted cyclopentadienes, such as bis(ethylcyclopentadienyl)zirconium zirconium dimethyl, bis(beta-phenylpropylcyclopentadienyl) zirconium dimethyl, bis(methylcyclopentadienyl)zirconium dimethyl, bis(n-butylcyclopentadienyl)zirconium dimethyl bis(cyclohexylmethylcyclopentadienyl)zirconium dimethyl bis(n-octyl-cyclopentadienyl)zirconium dimethyl, and haloalkyl and dihydride, and dihalide complexes of the above; dialkyl, trialkyl, tetra-alkyl, and penta-alkyl cyclopentadienes, such as bis(pentamethylcyclopentadienyl)zirconium diphenyl, bis(pentamethylcyclopentadienyl)zirconium dimethyl, bis(1,2-dimethylcyclopentadienyl)zirconium dimethyl and mono and dihalide and hydride complexes of the above; silicon, phosphorus, and carbon bridged cyclopentadiene complexes such as dimethylsilyldicyclopentadienyl zirconium dimethyl, methyl halide or dihalide, and methylene dicyclopentadienyl zirconium dimethyl, methyl halide, or dihalide. Mono, di and tri-silyl substituted cyclopentadienyl compounds such as bis(trimethylsilylcyclopentadienyl)zirconium dichloride and dimethyl bis(1,3-di-trimethylsilylcyclopentadienyl)zirconium dichloride and dimethyl and bis(1,2,4-tri-trimethylsilylcyclopentadienyl)zirconium dichloride and dimethyl. Carbenes represented by the formulae Cp₂Zr=CH₂P(C₆H₅)₂CH₃, and derivatives of these compounds such as <chemistry id="chem0003" num="0003"><img file="EP0441548B1_D0021.tif" /></chemistry>

Mixed cyclopentadienyl metallocene compounds such as cyclopentadienyl (pentamethyl cyclopentadienyl)zirconium dichloride, (1,3-di-trimethylsilylcyclopentadienyl) (pentamethylcyclopentadienyl) zirconium dichloride, and cyclopentadienyl(indenyl) zirconium dichloride can be employed.

Bis(cyclopentadienyl)hafnium dichloride, bis(cyclopentadienyl)hafnium dimethyl, bis(cyclopentadienyl)vanadium dichloride and the like are illustrative of other metallocenes.

Some preferred metallocenes are bis(cyclopentadienyl)zirconium dimethyl, bis(cyclopentadienyl)zirconium dichloride; bis(cyclopentadienyl)titanium dichloride; bis(methylcyclopentadienyl) zirconium dichloride; bis(methylcyclopentadienyl)titanium dichloride; bis(n-butylcyclopentadienyl)zirconium dichloride; dimethylsilyldicyclopentadienyl zirconium dichloride; bis(trimethylsilycyclopentadienyl)zirconium dichloride; and dimethylsilyldicyclopentadienyl titanium dichloride; bis(indenyl)zirconium dichloride; bis(4,5,6,7-tetrahydroindenyl )zirconium dichloride; the racemic and/or meso isomer of 1,2-ethylene-bridged bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride; the racemic and/or meso isomer of 1,1-dimethylsilyl-bridged bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride; and the racemic and/or meso isomer of 1,1-dimethylsilyl-bridged bis(methylcyclopentadienyl)zirconium dichloride.

The alumoxane compounds useful in the polymerization process may be cyclic or linear. Cyclic alumoxanes may be represented by the general formula (R-Al-O)_n while linear alumoxanes may be represented by the general formula R(R-Al-O)n'AlR₂. In the general formula R is a C₁-C₅ alkyl group such as, for example, methyl, ethyl, propyl, butyl and pentyl, n is an integer of from 3 to 20, and n' is an integer from 1 to about 20. Preferably, R is methyl and n and n' are 4-18. Generally, in the preparation of alumoxanes from, for example, aluminum trimethyl and water, a mixture of the linear and cyclic compounds is obtained.

The alumoxane can be prepared in various ways. Preferably, they are prepared by contacting water with a solution of aluminum trialkyl, such as, for examples, aluminum trimethyl, in a suitable organic solvent such as toluene or an aliphatic hydrocarbon. For example, the aluminum alkyl is treated with water in the form of a moist solvent. In an alternative method, the aluminum alkyl such as aluminum trimethyl can be desirably contacted with a hydrated salt such as hydrated copper sulfate or ferrous sulfate. Preferably, the alumoxane is prepared in the presence of a hydrated ferrous sulfate. The method comprises treating a dilute solution of aluminum trimethyl in, for example, toluene, with ferrous sulfate represented by the general formula FeS0₄.7H₂O. The ratio of ferrous sulfate to aluminum trimethyl is desirably about 1 mole of ferrous sulfate for 6 to 7 moles of aluminum trimethyl. The reaction is evidenced by the evolution of methane.

The mole ratio of aluminum in the alumoxane to total metal in the metallocenes which can be usefully employed can be in the range of about 0.5:1 to about 1000:1, and desirably about 1:1 to about 100:1. Preferably, the mole ratio will be in the range of 50:1 to about 5:1 and most preferably 20:1 to 5:1.

The solvents used in the preparation of the catalyst system are inert hydrocarbons, in particular a hydrocarbon that is inert with respect to the catalyst system. Such solvents are well known and include, for example, isobutane, butane, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, toluene, xylene and the like.

Polymerization is generally conducted at temperatures ranging between about 20° and about 300°C, preferably between about 30° and about 200°C. Reaction time is not critical and may vary from several hours or more to several minutes or less, depending upon factors such as reaction temperature, the monomers to be copolymerized, and the like. One of ordinary skill in the art may readily obtain the optimum reaction time for a given set of reaction parameters by routine experimentation.

The catalyst systems described herein are suitable for the polymerization of olefins in solution over a wide range of pressures. Preferably, the polymerization will be completed at a pressure of from about 10 to about 3,000 bar, and generally at a pressure within the range from about 40 bar to about 2,000 bar, and most preferably, the polymerization will be completed at a pressure within the range from about 50 bar to about 1,500 bar.

After polymerization and, optionally, deactivation of the catalyst (e.g., by conventional techniques such as contacting the polymerization reaction medium with water or an alcohol, such as methanol, propanol, isopropanol, etc., or cooling or flashing the medium to terminate the polymerization reaction), the product polymer can be recovered by processes well known in the art. Any excess reactants may be flashed off from the polymer.

The polymerization may be conducted employing liquid monomer, such as liquid propylene, or mixtures of liquid monomers (such as mixtures of liquid propylene and 1-butene), as the reaction medium. Alternatively, polymerization may be accomplished in the presence of a hydrocarbon inert to the polymerization such as butane, pentane, isopentane, hexane, isooctane, decane, toluene, xylene, and the like.

In those situations wherein the molecular weight of the polymer product that would be produced at a given set of operating conditions is higher than desired, any of the techniques known in the prior art for control of molecular weight, such as the use of hydrogen and/or polymerization temperature control, may be used in the process of this invention. If so desired, the polymerization may be carried out in the presence of hydrogen to lower the polymer molecular weight. Care should be taken to assure that terminal ethenylidene unsaturation is not reduced to less than about 30 percent of the polymer chains.

However, the polymers are preferably formed in the substantial absence of added H₂ gas, that is, the absence of H₂ gas added in amounts effective to substantially reduce the polymer molecular weight. More preferably, the polymerizations will be conducted employing less than 5 wppm, and more preferably less than 1 wppm, of added H₂ gas, based on the moles of the ethylene monomer charged to the polymerization zone.

When carrying out the polymerization in a batch-type fashion, the reaction diluent (if any), ethylene and alpha-olefin comonomer(s) are charged at appropriate ratios to a suitable reactor. Care must be taken that all ingredients are dry, with the reactants typically being passed through molecular sieves or other drying means prior to their introduction into the reactor. Subsequently, either the catalyst and then the cocatalyst, or first the cocatalyst and then the catalyst are introduced while agitating the reaction mixture, thereby causing polymerization to commence. Alternatively, the catalyst and cocatalyst may be premixed in a solvent and then charged to the reactor. As polymer is being formed, additional monomers may be added to the reactor. Upon completion of the reaction, unreacted monomer and solvent are either flashed or distilled off, if necessary by vacuum, and the low molecular weight copolymer withdrawn from the reactor.

The polymerization may be conducted in a continuous manner by simultaneously feeding the reaction diluent (if employed), monomers, catalyst and cocatalyst to a reactor and withdrawing solvent, unreacted monomer and polymer from the reactor so as to allow a residence time of ingredients long enough for forming polymer of the desired molecular weight and separating the polymer from the reaction mixture.

Most preferably, the polymers used in this invention are substantially free of ethylene homopolymer.

Preparation of Ethylene Alpha-olefin Polymer Substituted Mono- or Dicarboxylic Acid Material

The ethylene alpha-olefin polymer substituted mono- or dicarboxylic acid material, i.e., acid, anhydride or acid ester prepared according to this invention, includes the reaction product of ethylene alpha-olefin polymer with a monounsaturated carboxylic reactant comprising at least one member selected from the group consisting of (i) monounsaturated C₄ to C₁₀ dicarboxylic acid 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 C₁ to C₅ alcohol derived mono- or di-esters of (i); (iii) monounsaturated C₃ to C₁₀ monocarboxylic acid wherein the carbon-carbon double bond is allylic to the carboxy group, i.e, of the structure <chemistry id="chem0004" num="0004"><img file="EP0441548B1_D0022.tif" /></chemistry> and (iv) derivatives of (iii) such as C₁ to C₅ alcohol derived mono- or di-esters 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 unreacted polymer. The unreacted 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 ethylene-alpha-olefin polymer substituted monocarboxylic acid material and ethylene-alpha-olefin polymer substituted dicarboxylic acid material are intended to refer to the product mixture whether it has undergone such modification or not.

Accordingly, the functionality of the ethylene-alpha-olefin polymer substituted mono- and dicarboxylic acid material will be typically at least 0.7, preferably at least 0.8, and most preferably at least 0.9 and will vary typically from 0.7 to 2.8, preferably from 0.8 to 1.4, and most preferably from 0.9 to 1.3.

Exemplary of such monounsaturated carboxylic reactants are fumaric acid, itaconic acid, maleic acid, maleic anhydride, chloromaleic acid, chloromaleic anhydride, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and lower alkyl (e.g., C₁ to C₄ alkyl) acid esters of the foregoing, e.g., methyl maleate, ethyl fumarate, methyl fumarate, etc.

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.

While chlorination normally helps increase the reactivity of polyolefins with monounsaturated carboxylic reactant, it is not necessary with the present polymers due to their high terminal bond content and reactivity. Preferably, therefore, the polymer and the monounsaturated carboxylic reactant are 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. It has been surprisingly found that the terminally ethylenically-unsaturated ethylene alpha-olefin polymers used in this invention readily undergo such thermal "ene" reactions under conditions in which the formation of sediment, or other by-products contributing to product haze, is greatly minimized or avoided altogether. The improved low sediment ene reaction product mixture is preferably formed using a polymer (more preferably, ethylene-propylene copolymers) having a number average molecular weight of from 11,192 to 20,000, and a polydispersity of less than about 4, preferably less than about 3, e.g., from 1.1 to 3.5, most preferably from 1.2 to 3.

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 ene reaction products, particularly when employing maleic anhydride as the unsaturated acid reactant, with substantially no visibly observable 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 removed, 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 are contacted for a time and under conditions effective to form the desired ethylene alpha-olefin polymer substituted mono- or dicarboxylic acid material. Generally, the polymer and monounsaturated carboxylic reactant will be contacted in a polymer to unsaturated carboxylic reactant mole ratio usually from about 1:1 to 1:10, and preferably from about 1:1 to 1:5, at an elevated temperature, generally from about 120 to 260°C, preferably from about 160 to 240°C. 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. The reaction is preferably conducted in the substantial absence of O₂ and water (to avoid competing side reactions), and to this end can be conducted in an atmosphere of dry N₂ 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 N₂ to remove unreacted unsaturated carboxylic reactant.

The "ene" reaction product mixture thereby obtained has been surprisingly found to have a substantially reduced content of sediment or other solid by-products as impurities and can be employed, without filtering, centrifuging, clarification, phase separation or other conventional product purification treatments, as, e.g., an additive to lubricating oils or as intermediate in the preparation of derivative products for use in lubricating oils, as will be more completely described hereinafter.

The ene reaction product mixture is further improved by being substantially free of chlorine, that is, by having a chlorine content of less than about 25 ppm by weight, preferably less than about 10 ppm by weight.

The ene reaction product mixture comprising the desired ethylene-alpha-olefin substituted mono- or dicarboxylic acid material (e.g., ethylene-propylene polymer-substituted succinic anhydride) formed by the process of this invention will generally contain unreacted polymer, (that is, polymer which is unsubstituted by the mono- or dicarboxylic acid moiety), in a concentration of less than about 40 wt.% (e.g., from 5 to 35 wt.% ), more preferably less than about 30 wt.% (e.g from 10 to 25 wt.%) and will be generally characterized by a VR value ("viscosity ratio" value) of not greater than about 4.1, usually not greater than about 4.0, preferably from about 2.0 to 3.9, and most preferably from about 3.0 to 3.8. As used herein, the term "VR value" is intended to mean quotient determined by the expression (IV):<maths id="math0019" num=""><math display="block"><mrow><mtext>VR = </mtext><mfrac><mrow><mtext>VISb</mtext></mrow><mrow><mtext>VISa</mtext></mrow></mfrac></mrow></math><img file="EP0441548B1_D0023.tif" /></maths> wherein VISa is the kinematic viscosity (KV) of the ene reaction product mixture at 100°C in units of centistokes (as determined by ASTM Method No. D445) and VISb is the cold cranking simulator (CCS) viscosity of the ene reaction product mixture at -20°C in units of poise (as determined by ASTM Method No. D2602), wherein the measurements are made upon a 2 wt% solution of the ene reaction product mixture in an oil (herein termed the "reference oil") comprising S150N (solvent 150 neutral) mineral lubricating oil (Exxon Company U.S.A.), wherein the such reference oil is characterized by an ASTM D445 kinematic viscosity of 5.2 cSt (100°C) and an ASTM D2602 CCS viscosity of 19.2 poise (± 0.4 poise) (at -20°C). The "VR_r" value of the reference oil will then be about 3.7 ± 0.1.

Illustrative, therefore, of the improved ene reaction products of this invention are the following ethylene-propylene copolymer-substituted succinic acids and succinic anhydrides (EPSA), ethylene-butene-1 copolymer-substituted succinic acids and succinic anhydrides (EBSA) summarized in Table A below: <tables id="tabl0001" num="0001"><img file="EP0441548B1_D0024.tif" /></tables>

It will be understood that the ethylene alpha-olefin polymers of this invention which are charged to the reaction zone can be charged alone or together with (e.g., in admixture with) other polyalkenes derived from alkenes having from 1 to 20 carbon atoms (butene, pentene, octene, decene, dodecene, tetradodecene and the like) and homopolymers of C₃ to C₁₀, e.g., C₂ to C₅, monoolefins, and copolymers of C₂ to C₁₀, e.g., C₂ to C₅, monoolefins, said additional polymer having a number average molecular weight of at least about 900, and a molecular weight distribution of less than about 4.0, preferably less than about 3.0 (e.g, from 1.2 to 2.8). Preferred such additional olefin polymers comprise a major molar amount of C₂ to C₁₀, e.g. C₂ to C₅ monoolefin. Such olefins include ethylene, propylene, butylene, isobutylene, pentene, octene-1, styrene, etc. Exemplary of the additionally charged homopolymers is polypropylene, polyisobutylene, and poly-n-butene the like as well as interpolymers of two or more of such olefins such as copolymers of: ethylene and propylene (prepared by conventional methods other than as described above for the preferred ethylene alpha-olefin copolymers employed in this invention, that is, ethylene-propylene copolymers which are substantially saturated, wherein less than about 10 wt% of the polymer chains contain ethylenic unsaturation); butylene and isobutylene; propylene and isobutylene; etc. Other copolymers include those in which a minor molar amount of the copolymer monomers, e.g., 1 to 10 mole %, is a C₄ to C₁₈ non-conjugated diolefin, e.g., a copolymer of isobutylene and butadiene: or a copolymer of ethylene, propylene and 1,4-hexadiene; etc. The additional such olefin polymers charged to the reaction will usually have number average molecular weights of at least about 900, more generally within the range of about 1200 and about 5,000, more usually between about 1500 and about 4,000. Particularly useful such additional olefin polymers have number average molecular weights within the range of about 1500 and about 3,000 with approximately one double bond per chain. An especially useful additional such polymer is polyisobutylene. Preferred are mixtures of such polyisobutylene with ethylene-propylene copolymers wherein at least 30 wt% of the copolymer chains contain terminal ethenylidene monounsaturation as described above.

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.

Preparation of Nucleophilically-substituted Derivative Products

The polymer substituted carboxylic acids/anhydrides/esters of this invention, prepared as described above, can be contacted with a nucleophilic reactant, e.g., amines, alcohols, including polyols, amino-alcohols, reactive metal compounds, etc. to form the novel dispersants of this invention.

Amine compounds useful as nucleophilic reactants for reaction with the polymer substituted mono- or dicarboxylic acid materials include mono- and (preferably) polyamines, of about 2 to 60, preferably 2 to 40 (e.g. 3 to 20), total carbon atoms and about 1 to 12, preferably 3 to 12, and most preferably 3 to 9 nitrogen atoms in the molecule. These amines may be hydrocarbyl amines or may be hydrocarbyl amines including other groups, e.g, hydroxy groups, alkoxy groups, amide groups, nitriles, imidazoline groups, and the like. Hydroxy amines with 1 to 6 hydroxy groups, preferably 1 to 3 hydroxy groups are particularly useful. Preferred amines are aliphatic saturated amines, including those of the general formulas: <chemistry id="chem0005" num="0005"><img file="EP0441548B1_D0025.tif" /></chemistry> wherein R, R', R" and R''' are independently selected from the group consisting of hydrogen; C₁ to C₂₅ straight or branched chain alkyl radicals; C₁ to C₁₂ alkoxy C₂ to C₆ alkylene radicals; C₂ to C₁₂ hydroxy amino alkylene radicals; and C₁ to C₁₂ alkylamino C₂ to C₆ alkylene radicals; and wherein R''' can additionally comprise a moiety of the formula: <chemistry id="chem0006" num="0006"><img file="EP0441548B1_D0026.tif" /></chemistry> wherein R' is as defined above, and wherein r and r' can be the same or a different number of from 2 to 6, preferably 2 to 4; and t and t' can be the same or different and are numbers of from 0 to 10, preferably 2 to 7, and most preferably about 3 to 7, with the proviso that the sum of t and t' is not greater than 15. To assure a facile reaction, it is preferred that R, R', R", R''', r, r', t and t' be selected in a manner sufficient to provide the compounds of Formulas Va and Vb with typically at least one primary or secondary amine group, preferably at least two primary or secondary amine groups. This can be achieved by selecting at least one of said R, R', R" or R''' groups to be hydrogen or by letting t in Formula Vb be at least one when R''' is H or when the VI moiety possesses a secondary amino group. The most preferred amine of the above formulas are represented by Formula Vb and contain at least two primary amine groups and at least one, and preferably at least three, secondary amine groups.

Non-limiting examples of suitable amine compounds include: 1,2-diaminoethane; 1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane; polyethylene amines such as diethylene triamine; triethylene tetramine; tetraethylene pentamine; polypropylene amines such as 1,2-propylene diamine; di-(1,2-propylene)triamine; di-(1,3-propylene) triamine; N,N-dimethyl-1,3-diaminopropane; N,N-di-(2-aminoethyl ) ethylene diamine; N,N-di(2-hydroxyethyl)-1,3-propylene diamine; 3-dodecyloxypropylamine; amine; N-dodecyl-1,3-propane diamine; tris hydroxymethylaminomethane (THAM); diisopropanol amine: diethanol amine; triethanol amine; mono-, di-, and tri-tallow amines; amino morpholines such as N-(3-aminopropyl)morpholine; and mixtures thereof.

Other useful amine compounds include: alicyclic diamines such as 1,4-di(aminomethyl)cyclohexane, and heterocyclic nitrogen compounds such as imidazolines, and N-aminoalyl piperazines of the general formula (VII ): <chemistry id="chem0007" num="0007"><img file="EP0441548B1_D0027.tif" /></chemistry> wherein p₁ and p₂ are the same or different and are each integers of from 1 to 4, and n₁, n₂ and n₃ are the same or different and are each integers of from 1 to 3. Non-limiting examples of such amines include 2-pentadecyl imidazoline; N-(2-aminoethyl)piperazine; etc.

Commercial mixtures of amine compounds may advantageously be used. For example, one process for preparing alkylene amines involves the reaction of an alkylene dihalide (such as ethylene dichloride or propylene dichloride) with ammonia, which results in a complex mixture of alkylene amines wherein pairs of nitrogens are joined by alkylene groups, forming such compounds as diethylene triamine, triethylenetetramine, tetraethylene pentamine and isomeric piperazines. Low cost poly(ethyleneamines) compounds averaging about 5 to 7 nitrogen atoms per molecule are available commercially under trade names such as "Polyamine H", "Polyamine 400", "Dow Polyamine E-100", etc.

Useful amines also include polyoxyalkylene polyamines such as those of the formula (VIII): <chemistry id="chem0008" num="0008"><img file="EP0441548B1_D0028.tif" /></chemistry> where m has a value of about 3 to 70 and preferably 10 to 35; and the formula (IX): <chemistry id="chem0009" num="0009"><img file="EP0441548B1_D0029.tif" /></chemistry> where n''' has a value of about 1 to 40 with the provision that the sum of all the n''' values is from about 3 to about 70 and preferably from about 6 to about 35, and R⁴ is a polyvalent saturated hydrocarbon radical of up to ten carbon atoms wherein the number of substituents on the R⁴ group is represented by the value of "a", which is a number of from 3 to 6. The alkylene groups in either formula (VIII) or (IX) may be straight or branched chains containing about 2 to 7, and preferably about 2 to 4 carbon atoms.

The polyoxyalkylene polyamines of formulas (VIII) or (IX) above, preferably polyoxyalkylene diamines and polyoxyalkylene triamines, may have average molecular weights ranging from about 200 to about 4000 and preferably from about 400 to about 2000. The preferred polyoxyalkylene polyoxyalkylene polyamines include the polyoxyethylene and polyoxypropylene diamines and the polyoxypropylene triamines having average molecular weights ranging from about 200 to 2000. The polyoxyalkylene polyamines are commercially available and may be obtained, for example, from the Jefferson Chemical Company, Inc. under the trade name "Jeffamines D-230, D-400, D-1000, D-2000, T-403", etc.

A particularly useful class of amines are the polyamido and related amines disclosed in U.S. Patent 4,857,217 (the disclosure of which is hereby incorporated by reference in its entirety), which comprise reaction products of a polyamine and an alpha, beta unsaturated compound of the formula: <chemistry id="chem0010" num="0010"><img file="EP0441548B1_D0030.tif" /></chemistry> wherein X is sulfur or oxygen, Y is -OR⁸, -SR⁸, or -NR⁸(R⁹), and R⁵, R⁶, R⁷, R⁸ and R⁹ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl. Any polyamine, whether aliphatic, cycloaliphatic, aromatic, heterocyclic, etc., can be employed provided it is capable of adding across the acrylic double bond and amidifying with for example the carbonyl group (-C(O)-) of the acrylate-type compound of formula X, or with the thiocarbonyl group (-C(S)-) of the thioacrylate-type compound of formula X.

When R⁵, R⁶, R⁷, R⁸ or R⁹ in Formula X 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 R⁵ through R⁹ 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 R⁵ through R⁹ are aryl, the aryl group will generally contain from 6 to 10 carbon atoms (e.g., phenyl, naphthyl).

When one or more of R⁵ through R⁹ 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-ethylphenyl, o-ethyltolyl, and m-hexyltolyl. When one or more of R⁵ through R⁹ are aralkyl, the aryl component generally consists of phenyl or (C₁ to C₆) alkyl-substituted 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 R⁵ and R⁹ 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 R⁵ through R⁹ are heterocyclic, the heterocyclic group generally consists of a compound having at least one ring of 6 to 12 members in which on or more ring carbon atoms is replaced by oxygen or nitrogen. Examples of such heterocyclic groups are furyl, pyranyl, pyridyl, piperidyl, dioxanyl, tetrahydrofuryl, pyrazinyl and 1,4-oxazinyl.

The alpha, beta ethylenically unsaturated carboxylate compounds employed herein have the following formula: <chemistry id="chem0011" num="0011"><img file="EP0441548B1_D0031.tif" /></chemistry> wherein R⁵, R⁶, R⁷, and R⁸ 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 XI 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-methyl-2-heptenoic 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-cyclohexyl-2-methyl-2-pentenoic acid, 2-propenoic acid, methyl 2-propenoate, methyl 2-methyl 2-propenoate, methyl 2-butenoate, ethyl 2-hexenoate, 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.

Preferred compounds for reaction with the polyamines 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: <chemistry id="chem0012" num="0012"><img file="EP0441548B1_D0032.tif" /></chemistry> where R⁷ is hydrogen or a C₁ to C₄ alkyl group, such as methyl, and R⁸ is hydrogen or a C₁ to C₄ 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. 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 X wherein X' is oxygen, the resulting reaction product with the polyamine contains at least one amido linkage (-C(O)N&lt;) and such materials are herein termed "amido-amines." Similarly, when the selected alpha, beta unsaturated compound of formula X comprises a compound wherein X' is sulfur, the resulting reaction product with the polyamine contains thioamide linkage (-C(S)N&lt;) 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 X 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.

In summary, without considering other factors, equimolar amounts of reactants tend to produce a more linear amido-amine whereas excess of the formula X reactant tends to yield a more cross-linked amido-amine. It should be noted that the higher the polyamine (i.e., in greater the number of amino groups on the molecule) the greater the statistical probability of cross-linking since, for example, a tetraalkylenepentamine, such as tetraethylene pentamine <chemistry id="chem0013" num="0013"><img file="EP0441548B1_D0033.tif" /></chemistry> has more labile hydrogens than ethylene diamine.

These amido-amine adducts so formed are characterized by both amido and amino groups. In their simplest embodiments they may be represented by units of the following idealized formula: <chemistry id="chem0014" num="0014"><img file="EP0441548B1_D0034.tif" /></chemistry> wherein the R¹⁰'s, which may be the same or different, are hydrogen or a substituted group, such as a hydrocarbon group, for example, alkyl, alkenyl, alkynyl, aryl, etc., and A is a moiety of the polyamine which, for example, may be aryl, cycloalkyl, alkyl, etc., and n₄ is an integer such as 1-10 or greater.

The above simplified formula represents a linear amido-amine polymer. However, cross-linked polymers may also be formed by employing certain conditions since the polymer has labile hydrogens which can further react with either the unsaturated moiety by adding across the double bond or by amidifying with a carboxylate group.

Preferably, however, the amido-amines employed in this invention are not cross-linked to any substantial degree, and more preferably are substantially linear.

Preferably, the polyamine reactant contains at least one primary amine (and more preferably from 2 to 4 primary amines) group per molecule, and the polyamine and the unsaturated reactant of formula X 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 polyamine reactant per mole of the unsaturated reactant of formula X.

The reaction between the selected polyamine and acrylate-type compound is carried out at any suitable temperature. Temperatures up to the decomposition points 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 methanol 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.

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, the reaction can be run without the use of any solvent. In fact, where a high degree of cross-linking is desired, it is preferably 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.

As an example of the amido-amine adducts, the reaction of tetraethylene pentaamine (TEPA) with methyl methacrylate can be illustrated as follows: <chemistry id="chem0015" num="0015"><img file="EP0441548B1_D0035.tif" /></chemistry>

In a preferred embodiment, the nucleophilic reactant comprises a branched chain nitrogen containing adduct formed by a process which comprises: (a) contacting in a first liquid reaction mixture a first nitrogen-containing compound having at least two reactive nitrogen moieties with a polyfunctional reactant having within its structure a first functional group reactive with a -NH- group, and at least one additional functional group reactive with a -NH- group, in an amount and under conditions sufficient to selectively react the first functional groups in the polyfunctional reactant with the reactive nitrogen moieties to form a first reaction mixture containing a first adduct; and (b) contacting the first adduct with a second nitrogen-containing compound having at least two -NH- groups in an amount and under conditions sufficient to react the additional functional groups in the first adduct with said -NH- groups in the second nitrogen-containing compound to form a second adduct characterized by having within its structure on average (i) at least two nitrogen-containing moieties derived from the second nitrogen-containing compound per nitrogen-containing moiety derived from the first nitrogen-containing compound and (ii) at least two unreacted primary or secondary amine groups per molecule.

Preferably, the branched chain nitrogen-containing adduct comprises a branched amido-amine adduct, and more preferably to a star branched amido-amine adduct, formed by (a) reacting a first nitrogen-containing compound (e.g., ammonia or an organic amine) with an alpha, beta-unsaturated compound of the formula: <chemistry id="chem0016" num="0016"><img file="EP0441548B1_D0036.tif" /></chemistry> wherein X is sulfur or oxygen, Y is -OR⁸, -SR⁸, or -NR⁸(R⁹), and R⁵, R⁶, R⁷, R⁸ and R⁹ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above for formula X, to form a first adduct containing unreacted -C(X)-Y groups; and (b) reacting the first adduct with a polyamine (e.g., a polyalkylene polyamine) to form a second adduct containing unreacted -NH- groups (preferably primary amine groups) and comprising a branched amido-amine oligomer.

The first above adduct is prepared by contacting a polyfunctional reactant with a first nitrogen-containing compound containing at least two (e.g., from 2 to 20), preferably at least 3 (e.g., from 3 to 15), and most preferably from 3 to 8, reactive nitrogen moieties (that is, the total of the nitrogen-bonded H atoms) per molecule of the first nitrogen-containing compound. The first nitrogen-containing compound will generally comprise at least one member selected from the group consisting of ammonia, organic primary monoamines and organic polyamines containing at least one primary amine group or at least two secondary amine groups per molecule.

Most preferred as the first nitrogen-containing compound are members selected from the group consisting of ammonia and organic diprimary amines having from 2 to 12 carbon atoms and from 2 to 8 nitrogen atoms per molecule. Examples of such preferred organic diprimary amines are ethylene diamine, propylene diamine, diethylene triamine, dipropylene triamine, triethylene tetraamine, tripropylene tetraamine, tetraethylene pentaamine, tetrapropylene pentaamine, polyhexamethylene diamine, phenyl diamine.

The polyfunctional reactants useful in this invention include compounds having the formula: <chemistry id="chem0017" num="0017"><img file="EP0441548B1_D0037.tif" /></chemistry> wherein each X is independently O or S, W¹ and Y are the same or different, and preferably are each groups reactive with a -NH- group (i.e., with NH₃ or with primary or secondary amine groups), T is a substituted or unsubstituted hydrocarbon moiety, "a" is 0 or 1, "b" is 0 or 1, and "c" is an integer of at least 1, with the provisos that c = 1 when a = 0 and b = 1 when a = 1 , and with the further proviso that at least two of W¹, Y and T are reactive with a -NH- group.

The W¹ and Y functional groups are the same or different and include groups selected from the group consisting of: halide, -OR⁸, -SR⁸, -N(R⁸)(R⁹), -Z¹C(O)OR⁸, -C(O)R⁸, -(R⁷)C=C(R⁵) (R⁶), -Z¹-nitrile, -Z¹-cyano, -Z¹-thiocyano, -Z¹-isothiocyano, and -Z¹-isocyano, wherein R⁵, R⁶, R⁷, R⁸ and R⁹ are the same or different and are H or substituted or unsubstituted hydrocarbyl and wherein Z¹ is C₁ to C₂₀ (preferably C₁ to C₁₀) bivalent hydrocarbylene-(preferably alkylene or arylene). If a = b = 1, and T contains at least one &gt;C=C&lt; group, W¹ and Y can together further comprise -O- or -S-, to provide as reactants a class of ethylenically unsaturated and aromatic anhydrides and sulfo-anhydrides. Preferably the W¹ and Y groups in the selected polyfunctional reactant are different, and the reactivity of the W¹ moiety with -NH-groups, under the selected reaction conditions, is greater than the reactivity of the Y moieties with such -NH- groups to permit a substantially selective reaction of the W¹ groups with the first nitrogen-containing compound as described below. The relative reactivity of these groups on a polyfunctional reactant can be readily determined by conventional methods.

T is a polyvalent organic radical whose valence is equal to c + 1, wherein "c" is an integer of at least 1, preferably 1 to 3. Ordinarily T will not contain more than 20 carbon atoms and preferably not more than 10 carbon atoms. T can therefore include divalent groups such as as saturated and unsaturated hydrocarbylene (e.g., alkylene, alkenylene, arylene, and the like). When T is substituted, it can contain one or more substituents selected from the class consisting of halo, lower alkoxy, lower alkyl mercapto, nitro, lower alkyl, carboxy and oxo. It also may contain interrupting groups such as -O-, -S-, -S(O)-, -S(O)₂-, -NH-, -C(O)- and the like.

Exemplary of Z¹ groups are C₁ to C₁₀ branched and straight chained alkylene such as -(CH₂)_f-wherein "f" is an integer of from 1 to 10 (e.g., -CH₂-, -C₂H₄-, -C₃H₇-, -C₄H₈-, -C₅H₁₀-, and the like), and C₆ to C₂₀ arylene, and alkyl-substituted arylene such as -Ar-, -Ar-((CH₂)_f)-, -((CH₂)_f)-Ar-, -Ar-((CH₂)_f)-Ar- and the like, wherein Ar is phenylene, methylphenylene, naphthylene, methylnaphthylene and the like and wherein f is as defined above.

Examples of polyfunctional reactants wherein W¹ is (R⁵)(R⁶)C=C(R⁷)-, a = b = 0 and c = 1 are difunctional reactants comprising alpha, beta-ethylenically unsaturated compounds selected from the group consisting of compounds of the formula: <chemistry id="chem0018" num="0018"><img file="EP0441548B1_D0038.tif" /></chemistry> wherein X is sulfur or oxygen, Y is as defined above, and is preferably -OR⁸, -SR⁸, or - NR⁸(R⁹) , wherein R⁵, R⁶, R⁷, R⁸ and R⁹ are as defined above.

Exemplary of polyfunctional reactants wherein a = b = c = 1 are compounds of the formula: <chemistry id="chem0019" num="0019"><img file="EP0441548B1_D0039.tif" /></chemistry> wherein W¹, X, Y and T are as defined above and wherein W¹ and Y are different. Preferred members of this class of reactants are compounds of the formula: <chemistry id="chem0020" num="0020"><img file="EP0441548B1_D0040.tif" /></chemistry> wherein W¹ and Y are as defined above, wherein W¹ and Y are different and wherein T' is substituted or unsubstituted divalent C₁ to C₂₀ (preferably, C₁ to C₁₀) alkylene or alkenylene, e.g -C₂H₄-, -(CH₂)₃-, -(CH₂)₄-, -CH=CH-, -C(CH₂)-CH₂-, and the like, or C₆ to C₂₀ (preferably, C₆ to C₁₄) divalent substituted or unsubstituted arylene such as phenylene, naphthylene, bisphenylene, -phenyl-O-phenyl- and the like.

Exemplary of polyfunctional reactants are compounds wherein a = b = c = 1, each X is O, T contains a &gt;C=C&lt; group and wherein W¹ and Y together comprise -O- or -S- are: <chemistry id="chem0021" num="0021"><img file="EP0441548B1_D0041.tif" /></chemistry> chloromaleic anhydride, and the like.

Exemplary of polyfunctional reactants wherein a = b = 1 and c &gt; 1 are compounds of the formula: <chemistry id="chem0022" num="0022"><img file="EP0441548B1_D0042.tif" /></chemistry> wherein W¹, X, Y, T and "c" are as defined above and wherein W¹ and Y are different.

Exemplary of the polyfunctional reactants wherein a = 0 and b = c = 1 are bisfunctional compounds of the formula: <chemistry id="chem0023" num="0023"><img file="EP0441548B1_D0043.tif" /></chemistry> wherein W¹, X and Y are as defined above and wherein W¹ and Y are different.

Also useful as polyfunctional reactants in the present invention are compounds of the formula: <chemistry id="chem0024" num="0024"><img file="EP0441548B1_D0044.tif" /></chemistry> wherein R⁵ and X are as defined above, and wherein "d1" and "d2" are each integers of from 1 to 10; compounds of the formula: <chemistry id="chem0025" num="0025"><img file="EP0441548B1_D0045.tif" /></chemistry> wherein R⁵, R⁶, and R⁷ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above, and wherein Y" comprises a reactive functional group selected from the group consisting of: halide, -OR⁸, -SR⁸, -N(R⁸)(R⁹), -Z¹C(O)OR⁸ and -(R⁷)C=C(R⁵)(R⁶), wherein R⁵ to R⁹ are as defined above; and compounds of the formula: <chemistry id="chem0026" num="0026"><img file="EP0441548B1_D0046.tif" /></chemistry> wherein R⁵, R⁶, and R⁷ are the same or different and are hydrogen or substituted or unsubstituted hydrocarbyl as defined above.

Preferred compounds for reaction with the first nitrogen-containing compound in accordance with this invention are lower alkyl esters of acrylic and lower alkyl alpha-substituted acrylic acid. Illustrative of such preferred compounds are compounds of the formula: <chemistry id="chem0027" num="0027"><img file="EP0441548B1_D0047.tif" /></chemistry> where R⁷ is hydrogen or a C₁ to C₄ alkyl group, such as methyl, and R⁸ is hydrogen or a C₁ to C₄ 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 most preferred embodiments these compounds are acrylic and methacrylic esters such as methyl or ethyl acrylate, methyl or ethyl methacrylate.

The polyfunctional reactants useful in this invention are known materials and can be prepared by conventional methods known to those skilled in the art, which need not be decribed herein.

(a) Preparation of the First Adduct

The selected first nitrogen-containing compound and polyfunctional reactant are contacted in a first reaction mixture in an amount and under conditions sufficient to react the W¹ functional groups of the latter with at least a portion of, and preferably substantially all of, the reactive nitrogen moieties in the first nitrogen-containing compound.

In preparing the first adduct, it is preferred that the moles of the polyfunctional reactant employed be at least equal to the equivalents of the reactive nitrogen moieties in the first nitrogen-containing compound (that is, the sum of the nitrogen-bonded H atoms in the first nitrogen-containing compound). Preferably, a molar excess of the polyfunctional reactant of about at least 10%, such as 10-300%, or greater, for example, 25-200%, is employed. Larger excess can be employed if desired. For example, NH₃ is herein considered to have three reactive nitrogen moieties per molecule, and preferably at least 3 (e.g., from 3.3-10) moles of the polyfunctional reactant are employed in the first reaction mixture per mole of NH₃, to form a first adduct having, on average, three N-bonded moieties derived from the polyfunctional reactant, each such moiety containing the group: <chemistry id="chem0028" num="0028"><img file="EP0441548B1_D0048.tif" /></chemistry> wherein X, Y, T, "a", "b" and "c" are as defined above. Preferably, the first adduct contains on average at least 3 groups, more preferably from 3 to 20, and most preferably from 3 to 8, groups of formula.

The polyfunctional reactant and first nitrogen compound are preferably admixed by introducing the first nitrogen compound into the liquid reaction mixture containing the polyfunctional reactant, with mixing, to provide an excess of the polyfunctional reactant during the charging of the first nitrogen compound.

The conditions of the temperature and pressure employed for contacting of the first nitrogen-containing compound and the polyfunctional reactant can vary widely but will be generally from about -10 to 40°C (preferably from about 10 to 20°C). The progress of the reaction can be followed by IR to observe the disappearance of -N-H- bonds. Lower temperatures can be used, although longer reaction times may be required. Higher temperatures can also be employed but will tend to increase the amount of the less reactive Y functional groups which react with the reactive nitrogen moieties of the first nitrogen-containing compound, thereby decreasing the desired selectivity for the reaction with the more reactive W¹ functional groups.

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, the reaction can be run without the use of any solvent. It is preferred to avoid the use of an aqueous 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. Suitable solvents include alkanols (e.g., C₁ to C₆ alkanols such as methanol, isopropanol, ethanol and the like), ethers, xylene, benzene, toluene, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and the like.

The resulting first adduct product mixture is then preferably treated, as by stripping or sparging (with, e.g, nitrogen gas) (e.g., from about 20 to about 100°C) optionally under vacuum to remove any volatile reaction by-products and unreacted polyfunctional reactant to minimize the reaction of the second nitrogen-containing compound therewith in the second stage of the process of the present invention. Therefore, the second liquid reaction mixture, wherein the second adduct is formed, is preferably substantially free of unreacted polyfunctional reactant, e.g., contains less than about 1 wt%, and more preferably about 0.1 wt% unreacted polyfunctional reactant.

The average degree of branching in the first adduct is increased as the number of reactive nitrogen moieties in the first nitrogen-containing compound increases.

The average degree of branching ("DB₁") of the first adduct can be calculated from the expression:<maths id="math0020" num=""><math display="block"><mrow><msub><mrow><mtext>DB</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><msub><mrow><mtext> = [3(n</mtext></mrow><mrow><mtext>a</mtext></mrow></msub><msub><mrow><mtext>) + 2(n</mtext></mrow><mrow><mtext>p</mtext></mrow></msub><msub><mrow><mtext>) + (n</mtext></mrow><mrow><mtext>s</mtext></mrow></msub><mtext>)] x c</mtext></mrow></math><img file="EP0441548B1_D0049.tif" /></maths> wherein "n_a" is 1 when ammonia is employed as the first nitrogen-containing compound and is zero when ammonia is not used, and wherein "n_p" and "n_s" are the number of primary and secondary amine groups, respectively, in the organic amine, if employed as the first nitrogen-containing compound, and wherein "c" is an integer of at least 1 (and is equal to (r - 1), wherein "r" is the number of functional groups in each molecule of the polyfunctional reactant which are reactive with a -NH- group, as defined above). DB₁ in the first adduct is at least 2 (e.g., from 2 to 30 ) , preferably at least 3 (e.g., from 3 to 20), and more preferably from 3 to 15. When the first nitrogen-containing compound comprises a mixture of ammonia and an organic amine the average degree of branching can be determined by giving each of the factors in the above expression their weighted average of each such nitrogen-containing compound incorporated into the first adduct.

(b) Second Nitrogen-containing Compound

The second nitrogen-containing compound will comprise at least one polyamine containing at least 2 (e.g. from 2 to 20), preferably at least 3 (e.g. from 3 to 15), and most preferably from 3 to 10, reactive nitrogen moieties, that is the total of the nitrogen-bonded H atoms per molecule of the second nitrogen-containing compound. The second nitrogen-containing compound will generally comprise at least one member selected from the group consisting of organic primary and secondary polyamines containing at least one primary amine group (and preferably containing at least two (e.g., 2 to 6, preferably 2 to 4) primary amine groups) or at least two secondary amine groups per molecule. Generally, the organic polyamines will contain from about 2 to 60, preferably 2 to 40 (e.g. 3 to 20), total carbon atoms and about 2 to 12, preferably 3 to 12, and most preferably from 3 to 8 (e.g., 5 to 9) total nitrogen atoms in the molecule. These amines may be hydrocarbyl amines or may be hydrocarbyl amines including other groups, e.g, hydroxy groups, alkoxy groups, amide groups, nitriles, imidazoline ine groups, and the like. Hydroxy amines with 1 to 6 hydroxy groups, preferably 1 to 3 hydroxy groups are particularly useful.

Commercial mixtures of amine compounds may advantageously be used. For example, one process for preparing alkylene amines involves the reaction of an involves the reaction of an alkylene dihalide (such as ethylene dichloride or propylene dichloride) with ammonia, which results in a complex mixture of alkylene amines wherein pairs of nitrogens are joined by alkylene groups, forming such compounds as diethylene triamine, triethylenetetramine, tetraethylene pentamine and isomeric piperazines. Low cost poly (ethyleneamines) compounds averaging about 5 to 7 nitrogen atoms per molecule are available commercially under trade names such as "Polyamine H", "Polyamine 400", "Dow Polyamine E-100", etc.

The second nitrogen-containing compound can comprise an amido-amine formed by reacting a polyamine with an alpha, beta-ethylenically unsaturated compound, e.g. by reacting polyethylene amines (e.g., tetraethylene pentaamine, pentaethylene hexamine, and the like), polyoxyethylene and polyoxypropylene amines, e.g., polyoxypropylene diamine, trismethylolaminomethane and pentaerythritol, and combinations thereof, with with an acrylate-type compound above, and most preferably with an acrylate-type reactant selected from the group consisting of lower alkyl(alky)-acrylates (e.g., methyl, ethyl, iso-propyl, propyl, iso-butyl, n-butyl, tert-butyl, etc., esters of methacrylic acid, acrylic acid, and the like).

Most preferred as the second nitrogen-containing compound are members selected from the group consisting of organic diprimary amines having from 2 to 30 carbon atoms, from 2 to 12 total nitrogen atoms and from 0 to 10 secondary nitrogen atoms per molecule. Examples of such preferred organic diprimary amines are ethylene diamine, propylene diamine, diethylene triamine, dipropylene triamine, triethylene tetraamine, tripropylene tetraamine, tetraethylene pentaamine, tetrapropylene pentaamine, polyamino cyclohexylmethane and the like.

(c) Preparation of Second Adduct

The first adduct, containing an average of at least 2 (e.g., 2 to 10), and preferably at least 3 (e.g. from 3 to 8), unreacted functional Y groups per molecule, is contacted with the second nitrogen-containing compound in an amount and under conditions sufficient to react the remaining functional groups with the reactive nitrogen moieties of the second nitrogen-containing compound to form a second adduct characterized by having within its structure on average (i) at least two, (e.g., 2 to 30), preferably at least 3 (e.g., 3 to 20), nitrogen-containing moieties derived from the second nitrogen-containing compound per nitrogen-containing moiety derived from the first compound and (ii) at least two (e.g., 2 to 6; preferably 2 to 4) unreacted primary or secondary amine groups.

The reaction between the selected polyamine and the first adduct is carried out at any suitable temperature. Temperatures up to the decomposition points 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 the first adduct was formed using 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 methanol or ethanol. As the reaction slows, the temperature is raised to push the reaction 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, yields of at least 95% are generally obtained.

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 (e.g., at about 25°C) 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, the reaction can be run without the use of any solvent. It is preferred to avoid the use of an aqueous 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. Suitable solvents include alkanols (e.g., C₁ to C₆ alkanols such as methanol, isopropanol, ethanol and the like), ethers, xylene, benzene, toluene, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and the like.

Steps (a) and (b) can be repeated if desired to form more highly branched adducts. For example, a second adduct formed as described above can comprise the "first nitrogen-containing compound" passed to the repeated step (a) and can be therein contacted with additional polyfunctional reactant (e.g., an alpha, beta-ethylenically unsaturated carboxylate), preferably in a molar excess to the reactive nitrogen moieties in the second adduct (that is, the total number of -N-H- bonds remaining unreacted in the second adduct), to form a more highly branched "first" adduct which can then be treated to remove the excess unreacted polyfunctional reactant and contacted in a separate step with an additional second nitrogen-containing compound, such as a polyalkylene polyamine, as described above. Such more highly branched nitrogen-containing adduct will be characterized as indicated above for the second adducts (that is, on average, will contain in its structure at least two unreacted primary or secondary amine groups, and at least two nitrogen-containing moieties derived from the additional second nitrogen-containing compound per nitrogen-containing moiety derived from the nitrogen-containing adduct so contacted in the repeat of step (a)) and can be employed in the subsequent reaction with the selected ethylene-alpha-olefin polymer substituted acid-producing material to form a dispersant of this invention.

The selected amine can be readily reacted with the selected material, e.g., the ethylene-propylene copolymer substituted succinic anhydride, by reacting an oil solution containing 5 to 95 wt.% of the polymer substituted mono- or dicarboxylic acid material at 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 or mixtures of imides and amides, rather than amides and salts.

Reaction ratios of polymer substituted mono- and dicarboxylic acid material to equivalents of amine as well as the other nucleophilic reactants described herein can vary considerably, depending on the reactants and type of bonds formed. When the polymer comprises a polymer substituted dicarboxylic acid material, containing dicarboxylic acid producing moieties derived from any of the above monounsaturated dicarboxylic acids, or anhydride or ester derivatives thereof, generally from 0.05 to 1.0, preferably from about 0.1 to 0. 6, e.g., 0.2 to 0.4, moles of dicarboxylic acid moiety content (e.g., grafted maleic anhydride content) is used, per equivalent of nucleophilic reactant, e.g., amine. For example, about 0.8 mole of a pentamine (having two primary amino groups and 5 equivalents of nitrogen per molecule) is preferably used to convert into a mixture of amides and imides, the product formed by reacting one mole of polymer with sufficient maleic anhydride to add 1.6 moles of succinic anhydride groups per mole of polymer, i.e., preferably the pentamine is used in an amount sufficient to provide about 0.4 mole (that is 1.6/[0.8 x 5] mole) of succinic anhydride moiety per nitrogen equivalent of the amine. If an amido-amine, as above, is employed, generally from 1 to 5, preferably from about 1.5 to 3 moles of dicarboxylic acid moiety content (e.g., grafted maleic anhydride content) is used per equivalent of amido-amine reactant, e.g., amine.

When the polymer comprises a polymer substituted monocarboxylic acid material, containing monocarboxylic acid producing moieties derived from any of the above monounsaturated monocarboxylic acids, or ester derivatives thereof, generally from 0.05 to 1.0, preferably from about 0.1 to 0.6, e.g., 0.2 to 0.4, moles of monocarboxylic acid moiety content (e.g., grafted acrylic acid content) is used, per equivalent of nucleophilic reactant, e.g., amine. If an amido-amine, as above, is employed, generally from 1 to 5, preferably from about 1.5 to 3 moles of monocarboxylic acid moiety content (e.g., grafted acrylic acid content) is used per equivalent of amido-amine reactant, e.g., amine.

It will be understood that the amine reactant can comprise one or a mixture of any of the above described amines, such as a mixture of an amido-amine and a polyalkylene polyamine. Preferably, the polymer substituted mono- or dicarboxylic acid producing material and amine will be contacted for a time and under conditions sufficient to react substantially all of the primary nitrogens in the amine reactant. The progress of this reaction can be followed by infrared 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.

Tris(hydroxymethyl) amino methane (THAM) can be reacted with the aforesaid polymer substituted acid material to form amides, imides or ester type additives as taught by U.K. 984,409, or to form oxazoline compounds and borated oxazoline compounds as described, for example, in U.S. 4,102,798; 4,116,876 and 4,113,639.

The ashless dispersants may also be esters derived from the aforesaid ethylene alpha-olefin polymer substituted mono- or dicarboxylic acid material and from hydroxy compounds such as monohydric and polyhydric alcohols or aromatic compounds such as phenols and naphthols, etc. The polyhydric alcohols are the most preferred hydroxy compound and preferably contain from 2 to about 10 hydroxy radicals, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and other alkylene glycols in which the alkylene radical contains from 2 to about 8 carbon atoms. Other useful polyhydric alcohols include glycerol, mono-oleate of glycerol, monostearate of glycerol, monomethyl ether of glycerol, pentaerythritol, dipentaerythritol, and mixtures thereof.

The ester dispersant may also be derived from unsaturated alcohols such as allyl alcohol, cinnamyl alcohol, propargyl alcohol, 1-cyclohexene-3-ol, and oleyl alcohol. Still other classes of the alcohols capable of yielding the esters of this invention comprise the ether-alcohols and amino-alcohols including, for example, the oxy-alkylene, oxy-arylene-, amino-alkylene-, and amino-arylene-substituted alcohols having one or more oxy-alkylene, amino-alkylene, aminoarylene or oxy-arylene radicals. They are exemplified by Cellosolve, Carbitol, N, N, N',N'-tetrahydroxy-trimethylene di-amine, and ether-alcohols having up to about 150 oxy-alkylene radicals in which the alkylene radical contains from 1 to about 8 carbon atoms.

The ester dispersant may be di-esters of succinic acids or acidic esters, i.e., partially esterified succinic acids; as well as partially esterified polyhydric alcohols or phenols, i.e., esters having free alcohols or phenolic hydroxyl radicals. Mixtures of the above illustrated esters likewise are contemplated within the scope of this invention.

The ester dispersant may be prepared by one of several known methods as illustrated for example in U.S. Patent 3,381,022. The ester dispersant may also be borated, similar to the nitrogen containing dispersants, as described above.

Hydroxyamines which can be reacted with the aforesaid ethylene alpha-olefin polymer substituted dicarboxylic acid material to form dispersants include 2-amino-1-butanol, 2-amino-2-methyl-1-propanol, p-(beta-hydroxyethyl)-aniline, 2-amino-1-propanol, 3-amino-1-propanol, 2-amino-2-methyl-1,3-propane-diol, 2-amino-2-ethyl-1,3-propanediol, N-(beta-hydroxypropyl)-N'-(beta-amino-ethyl)-piperazine, tris(hydroxymethyl) amino-methane (also known as trismethylolaminomethane), 2-amino-1-butanol, ethanolamine, beta-(beta-hydroxyethoxy)-ethylamine, and the like. Mixtures of these or similar amines can also be employed. The above description of nucleophilic reactants suitable for reaction with the ethylene alpha-olefin polymer substituted dicarboxylic acid or anhydride includes amines, alcohols, and compounds of mixed amine and hydroxy containing reactive functional groups, i.e., amino-alcohols.

Reactive metals or reactive metal compounds useful for reaction with the ethylene-alpha-olefin polymer substituted mono- and dicarboxylic acid materials of this invention are those which will form carboxylic acid metal salts with the ethylene-alpha-olefin polymer substituted mono- and dicarboxylic acid materials of this invention and those which will form metal-containing complexes with such dispersant derivative compositions produced by reacting the ethylene-alpha-olefin polymer substituted mono- and dicarboxylic acid materials with amines and/or alcohols as discussed above. Reactive metal compounds useful for the formation of such complexes are disclosed in U.S. Patent 3,306,908. Complex-forming metal reactants include the nitrates, nitrites, halides, carboxylates, phosphates, phosphites, sulfates, sulfites, carbonates, borates, and oxides of cadmium as well as metals having atomic numbers from 24 to 30 (including chromium, manganese, iron, cobalt, nickel, copper and zinc). These metals are the so-called transition or co-ordination metals, i.e., they are capable of forming complexes by means of their secondary or co-ordination valence. Specific examples of the complex-forming metal compounds useful as the reactant in this invention are cobaltous nitrate, cobaltous oxide, cobaltic oxide, cobalt nitrite, cobaltic phosphate, cobaltous chloride, cobaltic chloride, cobaltous carbonate, chromous acetate, chromic acetate, chromic bromide, chromous chloride, chromic fluoride, chromous oxide, chromium dioxide, chromic oxide, chromic sulfite, chromous sulfate heptahydrate, chromic sulfate, chromic formate, chromic hexanoate, chromium oxychloride, chromic phosphite, manganous acetate, manganous benzoate, manganous carbonate, manganese dichloride, manganese trichloride, manganous citrate, manganous formate, manganous nitrate, manganous oxalate, manganese monooxide, manganese dioxide, manganese trioxide, manganese heptoxide, manganic phosphate, manganous pyrophosphosate, manganic metaphosphate, manganous hypophosphite, manganous valerate, ferrous acetate, ferric benzoate, ferrous bromide, ferrous carbonate, ferric formate, ferrous lactate, ferrous nitrate, ferrous oxide, ferric oxide, ferric hypophosphite, ferric sulfate, ferrous sulfite, ferric hydrosulfite, nickel dibromide, nickel dichloride, nickel nitrate, nickel dioleate, nickel stearate, nickel sulfite, cupric propionate, cupric acetate, cupric metaborate, cupric benzoate, cupric formate, cupric laurate, cupric nitrite, cupric oxychloride, cupric palmitate, cupric salicylate, zinc benzoate, zinc borate, zinc bromide, zinc chromate, zinc dichromate, zinc iodide, zinc lactate, zinc nitrate, zinc oxide, zinc stearate, zinc sulfite, cadmium benzoate, cadmimum carbonate, cadmium butyrate, cadmium chloroactate, cadmium fumerate, cadmium nitrate, cadmium di-hydrogenphosphate, cadmium sulfite, and cadmium oxide. Hydrates of the above compounds are especially convenient for use in the process of this invention.

From the foregoing description, it is apparent that the ethylene-alpha-olefin polymer substituted mono- and dicarboxylic acid materials of this invention can be reacted with any individual amine, alcohol, reactive metal, reactive metal compound or any combination of two or more of any of these; that is, for example, one or more amines, one or more alcohols, one or more reactive metals or reactive metal compounds, or a mixture of any of these. The mixture can be a mixture of two or more amines, a mixture of two or more alcohols, a mixture of two or more metals or reactive metal compounds, or a mixture of two or more components selected from amines and alcohols, from amines and reactive metals or reactive metal compounds, from alcohols and reactive metals compounds, or one or more components from each of the amines, alcohols, and reactive metal or reactive metal compounds. Furthermore, the ethylene-alpha-olefin polymer substituted mono- and dicarboxylic acid materials of this invention can be reacted with the amines, alcohols, reactive metals, reactive metal compounds, or mixtures thereof, as described above, simultaneously (concurrently) or sequentially in any order of reaction.

A preferred group of ashless dispersants are those derived from ethylene-propylene copolymer substituted with succinic anhydride groups (referred to herein as "EPSA") and reacted with polyethylene amines, e.g., tetraethylene pentamine, pentaethylene hexamine, polyoxyethylene and polyoxypropylene amines, e.g., polyoxypropylene diamine, trismethylolaminomethane and pentaerythritol, and combinations thereof. One particularly preferred dispersant combination involves a combination of (A) ethylene-propylene copolymer substituted with succinic anhydride groups and reacted with (B) a hydroxy compound, e.g., pentaerythritol, (C) a polyoxyalkylene polyamine, e.g., polyoxypropylene diamine, and (D) a polyalkylene polyamine, e.g. polyethylene diamine and tetraethylene pentamine using about 0.3 to about 2 moles each of (B) and (D) and about 0.3 to about 2 moles of (C) per mole of (A) as described in U.S. Patent 3,804,763. Another preferred dispersant combination involves the combination of (A) ethylene-propylene copolymer succinic anhydride with (B) a polyalkylene polyamine, e.g., tetraethylene pentamine, and (C) a polyhydric alcohol or polyhydroxy-substituted aliphatic primary amine, e.g., pentaerythritol or trismethylolaminomethane as described in U.S. Patent 3,632,511.

The dispersant materials of this invention are preferably characterized by a VR' value of not greater than about 4.1, preferably not greater than about 4.0, e.g., from about 2.5 to 4.0, and most preferably from about 3.5 to 3.9. As used herein, the term "VR' value" is intended to refer to the quotient obtained by the expression (XXX):<maths id="math0021" num=""><math display="block"><mrow><mtext>VR' = </mtext><mfrac><mrow><mtext>VIS'b</mtext></mrow><mrow><mtext>VIS'a</mtext></mrow></mfrac></mrow></math><img file="EP0441548B1_D0050.tif" /></maths> wherein VIS'a is the kinematic viscosity (ASTM Method D445) of the dispersant material at 100°C in units of centistokes, and VIS'b is the cold cranking simulator (CCS) viscosity (ASTM Method D2602) at -20°C in units of poise, as determined at a dispersant material polymer concentration of 2 wt.% in the reference oil as defined above for Formula IV. Preferably, the disperant materials of this invention are also characterized by a VR'/VR_r ratio of not greater than about 1.11, more preferably not greater than about 1.09, still more preferably from about 0.7 to 1.08 and most preferably from about 0.9 to 1.05, wherein VR_r3.7 ± 0.1 for the reference oil.

Another aspect of this invention involves the post treatment of the nitrogen or ester containing dispersant materials. The process for post-treating said nitrogen or ester containing dispersant materials is analogous to the post-treating processes used with respect to derivatives of conventional ethylene copolymers of the prior art. Accordingly, the same reaction conditions, ratio of reactants and the like can be used.

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, C₁ to C₃₀ 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 the ethylene-alpha-olefin polymer-substituted mono- and dicarboxylic acid materials employed in 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. The same post-treating reagents are used with the dispersant materials prepared from a combination of polyamines and polyols. However, when the dispersant materials are derived from polyols, and that is, when they are esters, the post-treating reagents are usually selected from the group consisting of boron oxide, boron oxide hydrate, boron halides, boron acids, esters of boron acids, sulfur, sulfur chlorides, phosphorus sulfides, phosphorus oxides, epoxides, and episulfides.

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 (HB0₂)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.

As a further feature of the present invention, the (A) ethylene-alpha-olefin polymer substituted mono- and di-carboxylic acid materials of this invention can be admixed, prior to, after or during being contacted with the selected nucleophilic reagant, with (B) a conventional polyolefin-substituted mono- or dicarboxylic acid material derived from any of the polyolefins discussed above as being useful as a mixed charge with the ethenylenically unsaturated ethylene-alpha-olefin polymers in the formation of the ethylene-alpha-olefin polymer substituted mono-and di-carboxylic acid materials of this invention. The ethlyene-alpha-olefin polymer substituted mono- and di-carboxylic acid materials of this invention and the polyolefin-substituted mono- or dicarboxylic acid material will be generally admixed prior to contact with the selected nucleophilic reagant, e.g., alkylene polyamine. Such mixtures will generally employ a weight:weight ratio of ethlyene-alpha-olefin polymer substituted mono-and di-carboxylic acid materials of this invention ion to polyolefin-substituted mono- or dicarboxylic acid material from about 10:90 to 90:10, preferably from about 20:80 to 80:20, and more preferably from about 40:60 to 60:40. Especially preferred are mixtures of ethylene-propylene copolymer-substituted succinic anhydride materials of this invention and polybutyl-substituted succinic anhydride (derived from polyisobutylene, poly-n-butene, or mixtures thereof, having a number average molecular weight as described above for the above conventional polyolefins, e.g., 900 - 5,000, more usually from about 1300 to 3,000). The resulting mixtures can then be contacted for reaction with the selected nucleophilic reagent as described above for formation of dispersant materials having improved viscosity properties, wherein the VR' of the resulting dispersant material is preferably less than the VR' of the corresponding dispersant prepared from the polyolefin-substituted mono- or dicarboxylic acid material alone. The resulting mixed dispersant materials can also be treated with any of the above-described post-treatment methods for incorporation of additional functional groups thereon, such as boron, hydroxy, ester, epoxy, lactone, sulfur, metals and the like, as discussed above.

OLEAGINOUS COMPOSITIONS

The dispersants prepared according to the present invention can be incorporated into a lubricating oil (or a fuel) in any convenient way. Thus, these dispersants 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 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.

When the products prepared according to the invention are incorporated into crude oil refinery process streams and other hydrocarbon fluid process streams, they function as antifoulants and will be generally used, e.g., in amounts of up to 100 ppm, e.g., 5 to 50 ppm, in the same manner as the macrocyclic polyamine additive as described in U.S. Patent 4,569,750, the disclosure of which is hereby incorporated by reference, in its entirety.

The dispersant products prepared according to the present invention possess very good dispersant properties as measured herein in a wide variety of environments. Accordingly, the dispersant products are used by incorporation and dissolution into oleaginous materials such as fuels and lubricating oils. When the dispersant products 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.

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 dispersant products of the present invention find their primary utility in lubricating oil compositions which employ a base oil in which the additives re 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 additive mixtures 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 hydraulic fluids, power steering fluids and the like. Gear lubricants, industrial oils, pump oils and other lubricating oil compositions can also benefit from the incorporation therein of the additive mixtures 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 viscosity index improvers, antioxidants, corrosion inhibitors, detergents (e.g., neutral and basic alkaline earth metal sulfonates, phenates and salicylates), dispersants, pour point depressants, antiwear agents (e.g., zinc dihydrocarbyl dithiophosphates), friction modifiers, and other ashless dispersant (e.g., polyisobutenyl succinimides) and borated derivatives thereof), antioxidants, etc.

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 of 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 ashless dispersants 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 polycarboxylic esters thereof, for example, the acetic acid esters, mixed C₃-C₈ fatty acid esters and C₁₃ 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 phthalate, 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 C₅ to C₁₂ 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-tert-butylphenyl)silicate, hexa-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic 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 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: <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Compositions</entry><entry namest="col2" nameend="col2" align="center">Wt.% A.I. (Preferred)</entry><entry namest="col3" nameend="col3" align="center">Wt.% A.I. (Broad)</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Viscosity Modifier</entry><entry namest="col2" nameend="col2" align="left">0.01-4</entry><entry namest="col3" nameend="col3" align="center">0.01-12</entry></row><row><entry namest="col1" nameend="col1" align="left">Detergents</entry><entry namest="col2" nameend="col2" align="left">0.01-3</entry><entry namest="col3" nameend="col3" align="center">0.01-20</entry></row><row><entry namest="col1" nameend="col1" align="left">Corrosion Inhibitor</entry><entry namest="col2" nameend="col2" align="left">0.01-1.5</entry><entry namest="col3" nameend="col3" align="center">.01-5</entry></row><row><entry namest="col1" nameend="col1" align="left">Oxidation Inhibitor</entry><entry namest="col2" nameend="col2" align="left">0.01-1.5</entry><entry namest="col3" nameend="col3" align="center">.01-5</entry></row><row><entry namest="col1" nameend="col1" align="left">Dispersant</entry><entry namest="col2" nameend="col2" align="left">0.1-8</entry><entry namest="col3" nameend="col3" align="center">.1-20</entry></row><row><entry namest="col1" nameend="col1" align="left">Pour Point Depressant</entry><entry namest="col2" nameend="col2" align="left">0.01-1.5</entry><entry namest="col3" nameend="col3" align="center">.01-5</entry></row><row><entry namest="col1" nameend="col1" align="left">Anti-Foaming Agents</entry><entry namest="col2" nameend="col2" align="left">0.001-0.15</entry><entry namest="col3" nameend="col3" align="center">.001-3</entry></row><row><entry namest="col1" nameend="col1" align="left">Anti-Wear Agents</entry><entry namest="col2" nameend="col2" align="left">0.001-1.5</entry><entry namest="col3" nameend="col3" align="center">.001-5</entry></row><row><entry namest="col1" nameend="col1" align="left">Friction Modifiers</entry><entry namest="col2" nameend="col2" align="left">0.01-1.5</entry><entry namest="col3" nameend="col3" align="center">.01-5</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Mineral Oil Base</entry><entry namest="col2" nameend="col2" align="left">Balance</entry><entry namest="col3" nameend="col3" align="center">Balance</entry></row></tbody></tgroup></table></tables>

When other additives are employed, it may be desirable, although not necessary, to prepare additive concentrates comprising concentrated solutions or dispersions 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. In the Examples, SA:PIB and SA:EP-polymer ratios are based upon the total PIB and EP-polymer, respectively, charged to the reactor as starting material, i.e., both the PIB and EP-polymer which reacts and the PIB and EP-polymer which remains unreacted. In the Examples, wt.% ethylene in the polymers was determined by FTIR (ASTM Method D3900). In the Examples, the "reference oil" was as defined above for Formula IV.

Example 41 illustrates the preparation of an EP copolymer for use in the process of the invention as illustrated in Example 42. Examples 43 and 44 illustrate the preparation of dispersants based on the product of Example 42. The remaining Examples are not examples of the invention and are for comparison.

EXAMPLE 1 - Preparation of Ethylene-Propylene Copolymer.

A 1 liter Zipperclave reactor (Autoclave Engineers) equipped with a water jacket for temperature control, with a septum inlet for syringe injection of catalyst, and with a supply of purified nitrogen, liquid propylene, and ethylene was used used in these polymerizations. The reactor was cleaned with hot toluene and then was purged well with dry nitrogen at 100°C. The reactor was cooled to 25°C and 10.0 cc of a 4.0 wt% toluene solution of methylalumoxane was injected along with 100 cc of distilled toluene at 0 psig under nitrogen. Liquid propylene monomer (200 cc) was added from a calibrated burette at 25°C. The reactor contents were stirred and heated to 115°C at which point the reactor pressure was 375 psig. 1.00 cc of a toluene solution of bis(n-butylcyclopentadienyl)zirconium dichloride (1.00 mg) was injected and ethylene at a pressure of 405 psig was immediately supplied. Ethylene was fed on pressure demand in order to keep the system pressure at 405 psig. The rate of ethylene flow was recorded continuously during the course of the polymerization. The reaction was continued for 15 minutes after which the reaction was stopped by rapidly depressuring and cooling the reactor to 25°C. The polymer product was collected and the toluene solvent was evaporated in an air stream. The polymer weight was determined to be 103.1 gms, and the polymer was analyzed by size-exclusion chromatography and found to contain 68 wt% ethylene and to have a number average molecular weight of 1100, a weight average molecular weight of 5400 and a polydispersity of 4.9. The polymer product was found to contain 2.5 wppm Zr and 1.75 wppm Cl.

EXAMPLE 2 - Preparation of Ethylene-Propylene Copolymer.

The polymerization was performed as in Example 1 except that the reactor temperature was maintained at 100°C and 1.00 mg of dimethylsilyldicyclopentadienyl zirconium dichloride was used as catalyst instead of bis(n-butylcyclopentadienyl) zirconium dichloride. The reactor pressure was maintained at 380 psig by a regulated ethylene supply. The yield of the copolymer was 111.2 gms and the polymer was determined to contain the ethylene content indicated in Table I and to have a number average molecular weight of 1390, a weight average molecular weight of 4030 and polydispersity of 2.9. The polymer product was found to contain 2.0 wppm Zr and 1.5 wppm Cl.

EXAMPLE 3 - Preparation of Ethylene-Propylene Copolymer.

The polymerization was performed as in Example 2 except that the reactor temperature was maintained at 90°C and 270 cc of liquid propylene was charged. The reactor pressure was maintained by a regulated ethylene supply. The yield of the copolymer was 16.3 gms and the polymer was determined to contain the ethylene content indicated in Table I and to have a number average molecular weight of 1750, a weight average molecular weight of 4960 and polydispersity of 2.8. The polymer product was found to contain 16 wppm Zr and 10 wppm Cl.

EXAMPLE 4 - Preparation of Ethylene-Propylene Copolymer.

The polymerization was performed as in Example 3 except that the reactor temperature was maintained at 80°C. The reactor pressure was maintained at 365 psig by a regulated ethylene supply for 1 hour. The yield of the copolymer was 234 gms and the polymer was determined to have a number average molecular weight of 2710, a weight average molecular weight of 7980 and polydispersity of 2.9. The polymer product was found to contain the ethylene content indicated in Table I and to contain 1.0 wppm Zr and 0.7 wppm Cl.

EXAMPLE 5 - Preparation of Ethylene Butene-1 Copolymer.

The polymerization was performed as in Example 3 except that 270 cc of liquid butene-1 was charged instead of the propylene. The reactor pressure was maintained at 167 psig by a regulated ethylene supply. The yield of the copolymer was 176.6 gms and the polymer was determined to have a number average molecular weight of 860, a weight average molecular weight of 2710 and polydispersity of 3.1. The polymer product was found to contain 1.5 wppm Zr and 1.1 wppm Cl.

EXAMPLES 6-10 - Preparation of Ethylene-Propylene Copolymer Substituted Succinic Anhydride (EPSA)

In a series of runs, the selected moles of the EP copolymers prepared as above and pulverized maleic anhydride are charged under dry N₂ at atmospheric pressure to a 100 ml. pressure reactor equipped with a stirrer and a thermocouple and heated by means of an electric heating mantle. No added solvent or diluent for the reactants is employed. Rather the reaction is conducted in the melt. In each run, the reaction mixture is heated to 70°C and the reactor is gently purged with dry N₂ by bubbling through the liquid reaction mass for 15 minutes. The purging is then ceased and the reactor temperature is raised to 220°C and kept at that temperature under autogenous pressure for 4 hours while stirring. The liquid reaction mixture is then cooled to about 60°C, and transferred to a glass beaker. Dry gaseous nitrogen is passed through the liquid to strip off unreacted maleic anhydride at about 140°C until no trace of maleic anhydride is detected with IR. The liquid product containing the EPSA and unreacted EP is analyzed for succinic anhydride by the following titration technique: a 2 g. sample of the polymer is dissolved in a solvent comprising 80 ml of THF, 6 ml of pyridine and 0.3 ml of water and titrated with a methanol solution of tetrabutyl ammonium hydroxide using thymol blue to a color end point. The acidity is calculated from the milliliters of base solution used. The product is also observed to determine the presence of any sediment.

In Example 11, the procedure of Example 6 is repeated except that the polymer was charged comprised a 50: 50 wt:wt mixture of the ethylene-propylene copolymer prepared as in Example 4 (M_n = 2710), and the polyisobutylene polymer which is employed in Comparative Example 13 (M_n = 1300). The data thereby obtained are the mole ratio of polymer and maleic anhydride charged, and the data thereby obtained are summarized in Table I. <tables id="tabl0003" num="0003"><img file="EP0441548B1_D0051.tif" /></tables>

COMPARATIVE EXAMPLES 12-14

To determine the degree of sediment formed in maleic anhydride reactions with conventional polyisobutylene polymers and conventional ethylene-propylene copolymers, the above procedure is repeated in a series of runs. The polyisobutylene polymer employed in Comparative Example 12 comprises Parapol 1300 polymer (Exxon Chemical Americas), and the polyisobutylene polymer employed in Comparative Example 13 comprises reactive polyisobutylene (ultra Vis30; BP Chemicals), having about 0.58 mole of terminal double bonds per mole of polymer (as determined by NMR) and a molecular weight distribution of about 3.0 (based on GPC). The ethylene-propylene copolymer of Comparative Example 14 (42 wt % ethylene, 58 wt % propylene; <maths id="math0022" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0052.tif" /></maths>_n = 1060; <maths id="math0023" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0053.tif" /></maths>_w = 1903) is prepared by conventional Ziegler Natta catalysis of ethylene and propylene using a catalyst system comprising VOCl₃ and aluminum sesquichloride, with H₂ as molecular weight control. The data thereby obtained are summarized in Table II. <tables id="tabl0004" num="0004"><img file="EP0441548B1_D0054.tif" /></tables>

The above results illustrate the surprisingly reduced sediment formation and high conversions achieved in the thermal "ene" reaction of maleic anhydride and the ethylene-propylene copolymers in accordance with the process of this invention in Examples 6-10, as compared to conventional polyisobutylene polymers (Comparative Examples 12-13) and conventional ethylene-propylene copolymers (Comparative Example 14 ).

EXAMPLES 15-20; COMPARATIVE EXAMPLES 21-22 - Preparation of Polyamine Dispersants

A series of dispersant materials are prepared employing the EPSA products prepared as in Examples 9 and 10, the mixed (EP/PIB)SA product of Example 11, the PIBSA product of Comparative Example 14, and various blends of the above PIBSA and EPSA products.

The succinic acid anhydride substituted polymers are dissolved in an equal amount by weight of a mineral oil, S150N. To the polymer solution is added a mixture of polyethylene polyamines having the average composition corresponding to tetraethylene pentamine and containing about 32.6 wt % N (PAM) and the mixture is heated to 140°C under nitrogen while stirring for about 2 to 4 hours. In each run, the molar ratio of total polymer to polyamine in terms of succinic acid equivalents to PAM charged is 2 to 1.

Viscosities of the resulting dispersant solutions are determined. Results of the viscometric studies are summarized in Table III below. <tables id="tabl0005" num="0005"><img file="EP0441548B1_D0055.tif" /></tables>

EXAMPLES 25-26; COMPARATIVE EXAMPLE 27

A series of dispersant blends are prepared employing the dispersant product solutions made as in Example 15 and Comparative Example 21, and the viscometrics measured, as summarized in Table IV below: <tables id="tabl0006" num="0006"><table frame="all"><title>Table IV</title><tgroup cols="6" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="26.25mm" /><colspec colnum="2" colname="col2" colwidth="26.25mm" /><colspec colnum="3" colname="col3" colwidth="26.25mm" /><colspec colnum="4" colname="col4" colwidth="26.25mm" /><colspec colnum="5" colname="col5" colwidth="26.25mm" /><colspec colnum="6" colname="col6" colwidth="26.25mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" /><entry namest="col4" nameend="col6" align="center">Viscometrics</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col3" align="center">Blend of Disp.</entry><entry namest="col4" nameend="col4" align="center">KV 100°C</entry><entry namest="col5" nameend="col5" align="center">CCS</entry><entry namest="col6" nameend="col6" /></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Example</entry><entry namest="col2" nameend="col2" align="center">Disp.</entry><entry namest="col3" nameend="col3" align="center">WT.%</entry><entry namest="col4" nameend="col4" align="center">cSt</entry><entry namest="col5" nameend="col5" align="center">-20°C, p</entry><entry namest="col6" nameend="col6" align="center">VR'</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">25</entry><entry namest="col2" nameend="col2" align="center">Ex.15</entry><entry namest="col3" nameend="col3" align="right">20</entry><entry namest="col4" nameend="col4" align="char" char=".">6.44</entry><entry namest="col5" nameend="col5" align="char" char=".">24.80</entry><entry namest="col6" nameend="col6" align="char" char=".">3.85</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Comp.Ex.21</entry><entry namest="col3" nameend="col3" align="right">80</entry><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /></row><row><entry namest="col1" nameend="col1" align="center">26</entry><entry namest="col2" nameend="col2" align="center">Ex.15</entry><entry namest="col3" nameend="col3" align="right">50</entry><entry namest="col4" nameend="col4" align="char" char=".">6.82</entry><entry namest="col5" nameend="col5" align="char" char=".">24.29</entry><entry namest="col6" nameend="col6" align="char" char=".">3.56</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Comp.Ex.21</entry><entry namest="col3" nameend="col3" align="right">50</entry><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /></row><row><entry namest="col1" nameend="col1" align="center">Comp.27</entry><entry namest="col2" nameend="col2" align="center">Comp.Ex.21</entry><entry namest="col3" nameend="col3" align="right">--</entry><entry namest="col4" nameend="col4" align="char" char=".">6.20</entry><entry namest="col5" nameend="col5" align="char" char=".">24.65</entry><entry namest="col6" nameend="col6" align="char" char=".">4.0</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">--</entry><entry namest="col2" nameend="col2" align="center">Reference Oil</entry><entry namest="col3" nameend="col3" align="right">0</entry><entry namest="col4" nameend="col4" align="char" char=".">5.19</entry><entry namest="col5" nameend="col5" align="char" char=".">19.20</entry><entry namest="col6" nameend="col6" align="char" char=".">3.70</entry></row></tbody></tgroup></table></tables> The lower VR' values signify a better viscometric balance that is desirable for dispersant to have. Results show that the viscometric behavior of PIB-based dispersants can be improved, as indicated by lower VR' values, by means of blending with the EP-copolymer based dispersants of this invention and also by making polyamine dispersants from a mix of PIBSA and EPSA dispersant intermediates. Moreover, the above results indicate that the VR' values for the dispersant product solutions of Examples 25 -26, unlike the comparative dispersant of Comparative Example 27, are lower than the VR_r value for the reference oil itself.

EXAMPLE 28

Ethylene-propylene copolymer (<maths id="math0024" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0056.tif" /></maths>_n = 1100) prepared as in Example 1 is reacted thermally with maleic anhydride as in Example 6 to give an EPSA product (%AI.54.5) which is diluted with an equal amount of S150N to give a 50 wt.% polymer solution. To 25 g of the solution, 0.75 g of the PAM (wt% N = 32.6) is added dropwise while stirring and light N₂ sparging at 140°C for 2 hours followed by nitrogen stripping for an hour at 140°C.

The resulting composition is 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 is 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 is used contains only a refined base mineral lubricating oil, a viscosity index improver, a pour point depressant and zinc dialkyldithiophosphate anti-wear additive. The oil contains no sludge dispersant. A quantity of such used oil is acquired by draining and refilling the taxicab crankcase at 1000 - 2000 mile intervals.

The SIB test is conducted in the following manner: the aforesaid used crankcase oil, which is milky brown in color, is freed of sludge by centrifuging for one hour at about 39,000 gravities (gs.). The resulting clear bright red supernatant oil is then decanted from the insoluble sludge particles thereby separated out. However, the supernatant oil still contains 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 are 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 are 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 is 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 are 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, is determined by drying the residue and weighing it. The results are reported as amount of precipitated sludge in comparison with the precipitated sludge of a blank not containing any additional additive, which blank is 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 is the additive as a sludge dispersant. In other words, if the additive gives 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 is used to determine varnish inhibition. Here, the test sample consists of 10 grams of lubricating oil containing a small amount of the additive being tested. The test oil to which the additive is admixed is of the same type as used in the above-described SIB test. The ten gram sample is heat soaked overnight at about 140°C and thereafter centrifuged to remove the sludge. The supernatant fluid of the sample is 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 SO₂, 1.4 volume percent NO and balance air is bubbled through the test sample. During the cooling phase, water vapor is bubbled through the test sample. At the end of the test period, which testing cycle can be repeated as necessary to determine the inhibiting effect of any additive, the wall surfaces of the test flask in which the sample is contained are visually evaluated as to the varnish inhibition. The amount of varnish imposed on the walls is 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 was rated 11.

10.00 grams of SIB test oil are mixed with 0.05 grams of the products of the Examples as described in Table II and tested in the aforedescribed SIB and VIB tests.

The test results are summarized below in Table V. <tables id="tabl0007" num="0007"><img file="EP0441548B1_D0057.tif" /></tables>

EXAMPLES 29 - 34

The procedure of Example 28 is repeated in a series of runs to prepare additional dispersant product solutions. The results thereby obtained, and the EPSA's employed, are summarized in Table VI. <tables id="tabl0008" num="0008"><img file="EP0441548B1_D0058.tif" /></tables>

EXAMPLE 35

The procedure of Example 6 is repeated except that 1 mole of ethylene-butene-1 copolymer (M_n = 860) prepared as in Example 5 is employed instead of the ethylene-propylene copolymer. The ethylene butene copolymer-substituted succinic anhydride (EBSA) product thereby obtained is found to contain about 76 wt % active ingredient EBSA and less than about 1 wppm of chlorine and to have a VR ratio of 3.9 (KV at 100°C = 5.77 cSt; CCS at -20°C = 22.63 poise).

EXAMPLES 36 - 39

In a separate series of runs, additional dispersants are prepared by employing the EPSA products of Examples 6, 7, 8 and 9 and the EBSA products of Example 35.

An amido amine ("AA") is prepared by reacting tetraethylene pentamine (TEPA) with methyl acrylate at a 1.5:1 TEPA:methyl acrylate molar ratio, to form a product mixture containing 29.3 wt.% total N, 6.1 wt.% primary N, and about 25 wt.% unreacted TEPA.

A mixture of 10 parts by weight of the EPSA (or EBSA) product formed in the indicated Example and 10 parts of S150N mineral oil are heated to 150°C under N₂. Then the desired amount of amido-amine prepared as above are added dropwise while stirring and light nitrogen sparging. The mixture is nitrogen stripped at 150°C for 3 hours and then filtered. The dispersant product solution is found to have the nitrogen content and kinematic viscosity reported in Table VII.

Each dispersant product solution is then tested as described in Examples 29 - 34 in the SIB and VIB tests. The results thereby obtained are also set forth in Table VII. <tables id="tabl0009" num="0009"><img file="EP0441548B1_D0059.tif" /></tables>

EXAMPLE 41 - Preparation of Ethylene-Propylene copolymer

A stirred 1500 cc steel autoclave reaction vessel which was equipped to perform continuous Ziegler polymerization reactions at pressures up to 2500 bar and temperatures up to 300°C was used. The reaction system was supplied with a thermocouple and pressure transducer to measure temperature and pressure continuously, and with means to supply continuously purified compressed ethylene and 1-propene. Equipment for continuously introducing a measured flow of catalyst solution at high pressure and equipment for rapidly venting and quenching the reaction and for collecting the polymer product was used in the reaction system. In this example, the polymerization was performed with a molar ratio of 1-propene to ethylene in the feed of 6.0 without the addition of a solvent. 1-Propene and ethylene at this molar ratio was continuously pumped into the reactor at a mass flow rate of 40 kg/hour and at a reactor pressure of 1300 bar. The reactor contents were stirred continuously at a rate of 1500 rpm. The temperature of the reactor was maintained at 175°C by pumping in a catalyst solution using a continuous high pressure injection pump at a rate of 1.7 liters/hour. The catalyst solution was prepared by mixing 2.035 grams of racemic dimethylsilyl bridged 3, 3'-bis(methylcyclopentadienyl) zirconium dichloride with 2.0 liters of 10 wt.% (1.4 molar in Al) methylalumoxane (Ethyl Corporation) and 8 liters of toluene. The yield of liquid ethylene-propene copolymer product was 3 kg/hour. The copolymer product had a number average molecular weight of 11,200 and a composition of 24 mole % propene. The copolymer product was analyzed by FTIR and 72 % of the polymer chains were found to have terminal ethenylidene unsaturation. The polymer was found to have a <maths id="math0025" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0060.tif" /></maths>_w of 21,600, and a <maths id="math0026" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0061.tif" /></maths>_w/<maths id="math0027" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0441548B1_D0062.tif" /></maths>_n of 1.93.

EXAMPLE 42 - Preparation of EPSA

In a 500 ml four-neck flask equipped with a thermometer, cold water condenser and stirrer, about 150 grams of the ethylene-propylene copolymer prepared in Example 41 was dissolved in 150 grams of S150N lubricating oil and 200 ml of heptane. The heptane was stripped out with dry N₂ gas, and then 2.7 grams of maleic anhydride was added at 100°C with stirring. The reaction mixture was slowly heated to 250°C and kept at this temperature for four hours with continuous stirring.

The liquid product mixture was then stripped with dry N₂ gas for 0.5 hour at 250°C. The product ethylene-propylene copolymer substituted with succinic anhydride groups (EPSA) was recovered and analyzed to have a Saponification Number of 5.38, corresponding to an average of 0.53 succinic groups per copolymer equivalent used in the reaction.

EXAMPLE 43 - Preparation of Dispersant

<ul id="ul0002" list-style="none" compact="compact"><li>(a) An amido-amine was prepared by reacting 1000 g. of polyamine (having an average composition corresponding to tetraethylenepentamine) and 230 g. of methylacrylate in a 2 liter, four neck round bottom flask provided with a stirrer, nitrogen sparger, air stirrer (?), condenser, thermometer, nitrogen oil bubbler, 500 ml. addition funnel, 1500 ml. pipette for sampling and 1/8 inch sapphire rotometer. The polyamine is added to the flask and methylacrylate is added over 2.1 hours with a nitrogen blanket on top of the addition funnel. After all methylacrylate is added, the mixture is heated to 120°C and then sparged with nitrogen for 1 hour, with periodic sampling to follow the progress of the reaction by infra-red analysis (which analysis indicated the disappearance of the ester peak). During the course of addition of the methylacrylate, the reaction temperature increased from 20°C to 43°C. The resulting amido-amine product analyzed to contain 28.9 wt.% nitrogen, and 3.93 wt.% primary amine.</li><li>(b) 50 grams of the EPSA product mixture obtained as in Example 42 was added to a reaction flask as used in Example 42 and diluted with 33 grams of S150 lubricating oil with stirring. The resulting mixture was heated to 150°C under N₂ and 0.59 g. of the amido-amine product of Example 43, part (a) was added dropwise while stirring and light N₂ sparging. After three hours, heptane was added to the reaction mixture, and the mixture was filtered. The filtered liquid mixture was then N₂ stripped for two hours at 150°C to remove the heptane. The oil solution of the dispersant product was then analyzed to contain 0.16 wt.%N.</li></ul>

EXAMPLE 44 - Preparation of Dispersant

<ul id="ul0003" list-style="none" compact="compact"><li>(a) A branched chain amine was prepared by charging 400 g. of methylacrylate in methanol (about 200 ml.) to a four necked reaction flask equipped with thermometer, stirrer, N₂ blanket and distilling hood, and 60 g. of ethylenediamine is added at a rate to keep the reaction temperature below 40°C, under a nitrogen blanket, and with light nitrogen stripping for 24 hours. When the reaction is completed, the reaction mixture is stripped with dry nitrogen gas to remove the excess methylacrylate and methanol until constant weight. The product analyzes for 53.45 wt.% C, 6.95 wt.% H and 6.84 wt.% N (theoretical 53.46 wt.% C, 7.9 wt.% H and 6.9 wt.% N). A 101 g. portion of the adduct thereby obtained was charged into a reaction flask together with 146 g. of triethylenetetramine, and the mixture was heated to 110°C with very light nitrogen sweeping. The reaction was continued until infra-red analysis indicated complete disappearance of the ester band (about 5 hours). The reaction mixture was then stripped at 100°C for 0.5 hour, and the product was collected. The resulting branched chain amine analyzed for 3.8 meq/g primary nitrogen and 25.9 wt.% total nitrogen.</li><li>(b) The procedure of Example 43, part (b) was repeated except that 0.64 g. of the branched chain amine of Example 44, part (a) above was used. The oil solution of the dispersant product was analyzed to contain 0.21 wt.% N.</li></ul>

The dispersant products of Examples 43 and 44 were determined to have a VR¹ value of 3.8 and 3.9, respectively, and the polymer prepared in Example 41 was determined to have a ratio of kinematic viscosity (cSt) to CCS viscosity (-20°C, poise of 3.4. [Measurements of dispersant viscosities were made as described above, and measurements for the polymer of Example 41 were made upon a polymer solution in S150N lubricating oil containing 2 wt.% of the polymer, using the methods as described above for formula IV.]