CN1256305A - Highly grafted multifunctional olefin copolymer viscosity index improver - Google Patents

Abstract

The present invention provides a novel additive comprising a highly grafted multifunctional olefin copolymer comprising a copolymer of ethylene and at least one C₃－C₂₃Graft and amine derived copolymers of an alpha-monoolefin and optionally a polyene wherein ethylene and at least one C₃－C₂₃Said copolymer of an alpha-monoolefin having grafted thereto an olefin copolymer of from 0.3 to 0.75 carboxyl groups per 1000 number average molecular weight units, and wherein said olefin copolymer has a number average molecular weight of 20000 —150000 lubricating oil concentrates and lubricating oil compositions containing the additives are also provided.

Description

Highly grafted multifunctional olefin copolymer viscosity index improver

The present invention relates to highly grafted multifunctional lubricant additives useful as improved viscosity index improvers when used in lubricating oil compositions. The present invention also relates to methods of extending lubricant drain intervals and improving fuel economy and fuel economy durability.

There is much published literature in the art regarding the use of polymeric additives in lubricating oil compositions. Ethylene-propylene copolymers and ethylene-alpha-olefin non-conjugated diene terpolymers have been further studied to provide bifunctional properties in lubricating oil compositions illustrating this type of lubricating oil additive.

USP4,089,794 discloses grafting of ethylene and one or more C ₃ -C ₂₈ α-olefins with ethylenically unsaturated carboxylic acid material solution, followed by reaction with carboxyl-bearing multifunctional material such as polyamine, polyol or hydroxylamine The resulting ethylene copolymer, the reaction product, is used as a sludge and varnish control additive in lubricating oils.

U.S. Patent 4,137,185 discloses a stabilized imine grafted ethylene copolymer additive for lubricants.

U.S.P4,146,489 discloses a graft copolymer, wherein the backbone polymer is an oil-soluble ethylene-propylene copolymer or ethylene-propylene-diene graft monomer C-vinylpyridine or N-vinylpyrrolidone A modified terpolymer that provides a dispersant viscosity index improver for lubricating oils.

USP4,320,019 discloses a multifunctional lubricating additive, which is an intermediate product of an acylation reaction formed by the reaction of a copolymer of ethylene and C ₃ -C ₈ α-monoolefin with an olefin carboxylic acid acylating agent, and then reacted with an amine prepared by the reaction.

U.S. Patent 4,340,689 discloses a method for grafting functional organic groups onto ethylene copolymers or ethylene-propylene-diene terpolymers.

U.S. Patent 4,357,250 discloses the reaction product of a copolymer and an alkene carboxylic acid by an "ene" reaction followed by reaction with a monoamine-polyamine mixture.

U.S. Patent 4,382,007 discloses a dispersant viscosity index improver prepared by reacting a polyamine-derived dispersant with an oxidized ethylene-propylene polymer or ethylene-propylene diene terpolymer.

U.S. Patent 4,144,181 discloses a polymer additive for fuels and lubricants comprising grafted ethylene copolymers reacted with polyamines, polyols or hydroxylamines and finally with alkaryl sulfonic acids.

WO96/39477 proposes a multi-grade lubricating oil comprising a low saturation base stock, less than 3% by mass of an ashless dispersant and a viscosity modifier. This document is silent on the highly grafted multifunctional viscosity index improvers of the present invention.

WO 94/13763 discloses mixed ethylene alpha-olefin copolymer multifunctional viscosity modifiers. This document is silent on the highly grafted multifunctional viscosity index improvers of the present invention.

U.S. Patent 4,863,623 mentions multifunctional olefin copolymer viscosity index improvers. This patent does not mention the functionality versus molecular weight relationship of the highly grafted multifunctional viscosity index improvers of the present invention.

U.S. Patent 5,075,383 discloses a process for the preparation of dispersant and antioxidant olefinic copolymer additives in which free radical grafting is accompanied by a reduction in the molecular weight of the copolymer due to mechanical shear.

U.S. Patent 5,556,923 discloses addition derivatized EPR or EPDM oil solutions. This patent does not mention the functionality versus molecular weight relationship of the highly grafted multifunctional viscosity index improvers of the present invention.

It is an object of the present invention to provide a novel highly grafted multifunctional olefin copolymer composition.

Another object of the present invention is to provide a highly grafted multifunctional lubricant additive effective for lubricating oil compositions to improve viscosity index, dispersibility and oxidation resistance, as well as to extend oil drain intervals and improve fuel economy and fuel economy durability.

Yet another object of the present invention is to provide a new lubricating oil composition containing the highly grafted multifunctional olefin copolymer additive of the invention and a concentrate providing the novel additive of the invention.

The novel highly grafted multifunctional olefin copolymers of the present invention comprise the reaction product of (1) an acylated olefin copolymer and (2) a polyamine compound selected from the group consisting of ethylene Copolymers or terpolymers of C ₃ -C ₂₃ α-olefins and optionally non-conjugated dienes or trienes, in which an ethylenically unsaturated carboxylic reactant has been grafted in an amount per 1000 counts Average molecular weight unit (Mn) 0.3-0.75 carboxyl groups:

其中，R¹是氢，-NH-芳基，-NH-芳烷基，-NH-烷基，或具有4-24个碳原子的支链或直链基团，该基团可以是烷基，链烯基，烷氧基，芳烷基，烷芳基，羟烷基，或氨基烷基；R²是-NH₂，CH₂-(CH₂)_n-NH₂，CH₂-芳基-NH₂，其中n是1-10的值；R³是氢，具有4-24个碳原子的烷基，链烯基，烷氧基，芳烷基，烷芳基；(a) N-arylphenylenediamine represented by the following formula:

Wherein, ^R is hydrogen, -NH-aryl, -NH-aralkyl, -NH-alkyl, or a branched or linear group with 4-24 carbon atoms, which can be an alkyl , alkenyl, alkoxy, aralkyl, alkaryl, hydroxyalkyl, or aminoalkyl; R ² is -NH ₂ , CH ₂ -(CH ₂ ) _n -NH ₂ , CH ₂ -aryl -NH ₂ , wherein n is a value of 1-10; R ³ is hydrogen, alkyl, alkenyl, alkoxy, aralkyl, alkaryl with 4-24 carbon atoms;

(b) an aminothiazole selected from aminothiazole, aminobenzothiazole, aminobenzothiadiazole and aminoalkylthiazole;

其中，R和R¹代表氢，或具有1-14个碳原子的烷基，链烯基，或烷氧基；(c) Aminocarbazole represented by the following formula:

Wherein, R and ^R represent hydrogen, or an alkyl, alkenyl, or alkoxy group with 1-14 carbon atoms;

(d) Aminoindole represented by the following formula: Wherein, R represents hydrogen, or an alkyl group with 1-14 carbon atoms;

(e) Aminopyrrole represented by the following formula: Wherein, R is a divalent alkylene group having 2-6 carbon atoms and ^R is hydrogen or an alkyl group having 1-14 carbon atoms;

其中，R是氢或具有1-14个碳原子的烷基；(f) Aminoindazolones represented by the following formula:

Wherein, R is hydrogen or an alkyl group with 1-14 carbon atoms;

其中，R可以不存在或是选自烷基，链烯基，芳烷基或芳基的C₁-C₁₀的直链或支链烃基；(g) Aminomercaptotriazole represented by the following formula:

Wherein, R may not exist or be selected from alkyl, alkenyl, aralkyl or aryl C ₁ -C ₁₀ linear or branched chain hydrocarbon groups;

(h) Aminobacid represented by the following formula: Wherein, R is hydrogen or an alkyl or alkoxy group having 1-14 carbon atoms;

(i) aminoalkylimidazoles, such as 1-(2-aminoethyl)imidazole, 1-(3-aminopropyl)imidazole; and

(j) Aminoalkylmorpholines, such as 4-(3-aminopropyl)morpholine.

The novel lubricant compositions of the present invention comprise an oil of lubricating viscosity and an effective amount of a highly grafted multifunctional olefin copolymer.

The polymer or copolymer matrix for the novel highly grafted multifunctional olefin copolymer additives of the present invention can be prepared from ethylene and propylene, or it can be prepared from ethylene and at least one alpha olefin in the _C3 - _C23 range In the higher alkenes to prepare.

Preferred polymers for use in the present invention are copolymers of ethylene and one or more _C3 - _C23 alpha olefins. Copolymers of ethylene and propylene are most preferred. Other alpha olefins suitable for use in place of propylene to form copolymers or in mixtures of ethylene and propylene to form terpolymers include 1-butene, 1-pentene, 1-hexene, 1-octene and styrene; α,ω-dienes such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene; branched chain α-olefins such as 4-methylbutene-1,5-methyl pentene-1 and 6-methylheptene-1; and mixtures thereof.

A third component can be used to prepare more complex polymer matrices often designated as copolymers. The third component generally used to prepare the copolymer matrix is a polyene monomer selected from non-conjugated dienes and trienes. Non-conjugated diene components are those having 5-14 carbon atoms in the chain. It is preferred that the diene monomer is characterized by the presence of a vinyl group in its structure and may include cyclic and bicyclic compounds. Representative dienes include 1,4-hexadiene, 1,4-cyclohexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-methylene-2- norbornene, 1,5-heptadiene and 1,6-octadiene. Mixtures of more than one diene may be used in making the copolymer. The preferred non-conjugated diene for use in preparing the terpolymer or copolymer matrix is 1,4-hexadiene.

The triene component will have at least 2 non-conjugated double bonds and up to 30 carbon atoms in the chain. Typical trienes used to prepare the copolymers of the present invention are 1-isopropylidene-3α,4,7,7α-tetrahydroindene, 1-isopropylidenedicyclopentadiene, dihydro-isodi Cyclopentadiene and 2-(2-methylene-4-methyl-3-pentenyl)[2.2.1]bicyclo-5-heptene.

Ethylene-propylene or higher α-olefin copolymers may consist of about 15-80 mole percent ethylene and about 85-20 mole percent C ₃ -C ₂₃ α-olefins, with a preferred molar ratio of about 35-75 mole percent ethylene and about 65- 25 mol% C ₃ -C ₂₃ α-olefin, more preferred ratio is 50-70 mol% ethylene and about 50-30 mol% C ₃ -C ₂₃ α-olefin, most preferred ratio is 55-65 mol% ethylene and about 45-35 mole % C ₃ -C ₂₃ α-olefins.

Various terpolymers of the above polymers may contain from about 0.1 to 10 mole percent of a non-conjugated diene or triene.

The polymer matrix, ethylene copolymer or terpolymer, is an oil-soluble linear or branched polymer with a number average molecular weight of about 20,000-150,000 as determined by gel permeation chromatography and usually Its preferred number average molecular weight is 30,000-110,000 as measured by standard.

The terms polymer and copolymer are used generally to include ethylene copolymers, terpolymers or interpolymers. These materials may contain small amounts of other olefinic monomers as long as the basic characteristics of the ethylene copolymers are not substantially altered.

The polymerization reactions used to form the ethylene-alpha-olefin copolymer matrix are generally carried out in the presence of conventional Ziegler-Narta or metallocene catalyst systems. The polymerization medium is not specific and may include solution, slurry or gas phase processes well known to those skilled in the art. When solution polymerization is used, the solvent may be any suitable inert hydrocarbon solvent which is liquid under the reaction conditions for the polymerization of alpha-olefins; examples of satisfactory hydrocarbon solvents include linear alkanes having 5-8 carbon atoms , hexane is preferred. Aromatic hydrocarbons, preferably aromatic hydrocarbons having a single benzene ring, such as benzene, toluene, etc.; and saturated cyclic hydrocarbons having the approximate boiling point ranges of the aforementioned linear alkanes and aromatic hydrocarbons, are particularly suitable. The solvent of choice may be one or a mixture of more of the above hydrocarbons. When slurry polymerization is used, the liquid phase used for the polymerization is preferably liquid propylene. Desirably, the polymerization medium is free of matrix which would interfere with the catalyst components.

Ethylenically unsaturated carboxylic acid species are then grafted onto the designated polymer backbone to form acylated ethylene copolymers. These carboxylic acid reactants suitable for grafting onto ethylene copolymers contain at least one vinyl bond and at least one, preferably two, carboxylic acids or their anhydrides or a polar group which can be converted by oxidation or hydrolysis to the desired Said carboxyl. It is preferred that the carboxylic acid reactant is selected from the group consisting of acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid reactants. More preferably the carboxylic reactant is selected from maleic acid, fumaric acid, maleic anhydride or a mixture of two or three thereof. Maleic anhydride or its derivatives are generally most preferred because of their commercial availability and ease of reaction. Itaconic acid or its anhydride is preferred in the case of unsaturated ethylene copolymers or terpolymers because of its tendency to reduce during free radical grafting, forming cross-linked structures.

The ethylenically unsaturated carboxylic acid material can typically donate one or two carboxyl groups per mole of reactant to the grafted polymer. That is, methyl methacrylate can donate one hydroxyl group per molecule to the grafted polymer, while maleic anhydride can donate two carboxyl groups per molecule to the grafted polymer.

The amount of carboxylic acid reactant grafted onto a given polymer backbone is such as to provide 0.3-0.75 carboxyl groups per 1000 number average molecular weight units of the polymer backbone, preferably 0.3-0.5 carboxyl groups per 1000 number average molecular weight units. For example, a copolymer matrix with an Mn of 20,000 is grafted with 6-10 carboxyl groups per polymer chain, or 3-5 moles of maleic anhydride per mole of polymer. Copolymers with Mn of 100,000 are grafted with 30-50 carboxyl groups per polymer chain, or with 15-25 moles of maleic anhydride per polymer chain. A functional minimum amount is that amount needed to achieve a minimum satisfactory dispersibility. It has been noted that the above-mentioned maximum functional amounts add little, if any, to the dispersing properties and other properties of the additive may be adversely affected.

This grafting reaction to form the acylated olefin copolymer is generally carried out in solution or in bulk in the presence of an auxiliary free radical initiator when in an extruder or intensive mixing device. When the polymerization is carried out in hexane solution, it is economically convenient to carry out the grafting reaction in hexane as described in U,S, P4,340,689, 4,670,515 and 4,948,842, which are hereby incorporated by reference . The resulting polymer intermediate is characterized by random functionality of carboxylic acid acylation in its structure.

In the batch process for forming acylated olefin copolymers, the olefin copolymers are added to rubber or plastic processing equipment such as extruders, intensifier mixers or masticators, heated to 150-400°C, and the ethylenically unsaturated carboxylic The acid reactant and free radical initiator are added separately to the molten polymer and allow grafting. According to U.S. P 5,075,383, which is hereby incorporated by reference, the reaction is carried out optionally under mixed conditions to allow shearing and grafting of ethylene copolymers. The processing equipment is typically purged with nitrogen to prevent oxidation of the polymer with the attendant venting of unreacted reactants and by-products of the grafting reaction. The residence time in the processing equipment is sufficient to provide the desired degree of acylation and to allow purification of the acylated copolymer by venting. Mineral lubricating oil or synthetic lubricating oil may optionally be added to the processing equipment after the vent period to dissolve the acylated copolymer.

Free radical initiators that can be used to graft the ethylenically unsaturated carboxylic acid species onto the polymer backbone include peroxides, hydroperoxides, peresters, and also azo compounds, preferably those with a boiling point greater than 100°C and at Compounds that donate free radicals are thermally decomposed in the grafting temperature range. Representative examples of these free radical initiators are azobutyronitrile, dicumyl peroxide, 2,5-dimethylhexane-2,5-bis-tert-butyl peroxide and 2,5- Dimethyl-hex-3-yne-2,5-bis-tert-butyl peroxide. The initiator is used in an amount of about 0.005% to about 1% by weight of the reaction mixture.

Other methods known in the art for reacting ethylene-olefin copolymers with ethylenically unsaturated carboxylic acid reactants, such as halogenation reactions, thermal or "ene" reactions, or combinations thereof, may be used in place of the free radical grafting method . These reactions are usually performed in mineral oil or in bulk by heating the reactants at 250-400°C under an inert atmosphere to avoid generation of free radicals or oxidative by-products. The "ene" reaction is the preferred grafting method when the ethylene-olefin copolymer contains unsaturation. In order to achieve the high grafting levels required by the present invention, 0.3-0.5 carboxyl groups per 100 Mn, it may be necessary to accompany or carry out the "ene" or thermal grafting reaction with a free radical grafting reaction.

The polymer intermediate having carboxylic acid acylation function is reacted with a polyamine compound selected from the group consisting of:

(a) N-arylphenylenediamine represented by the following formula: Wherein, ^R is hydrogen, -NH-aryl, -NH-aralkyl, -NH-alkyl, or a branched or linear group with 4-24 carbon atoms, which can be an alkyl , alkenyl, alkoxy, aralkyl, alkaryl, hydroxyalkyl, or aminoalkyl; R ² is -NH ₂ , CH ₂ -(CH ₂ ) _n -NH ₂ , CH ₂ -aryl -NH ₂ , wherein n is a value of 1-10; R ³ is hydrogen, alkyl, alkenyl, alkoxy, aralkyl, alkaryl with 4-24 carbon atoms;

(b) aminothiazoles consisting of aminothiazoles, aminobenzothiazoles, aminobenzothiadiazoles and aminoalkylthiazoles;

其中，R和R¹代表氢，或具有1-14个碳原子的烷基，链烯基或烷氧基；(c) Hydrocarbazole represented by the following formula:

Wherein, R and ^R represent hydrogen, or an alkyl, alkenyl or alkoxy group with 1-14 carbon atoms;

(d) Aminoindole represented by the following formula: Wherein, R represents hydrogen, or an alkyl group with 1-14 carbon atoms;

其中，R是具有2-6个碳原子的2价亚烷基和R¹是氢或具有1-14个碳原子的烷基；(e) Aminopyrrole represented by the following formula:

Wherein, R is a divalent alkylene group having 2-6 carbon atoms and ^R is hydrogen or an alkyl group having 1-14 carbon atoms;

其中，R是氢或具有1-14个碳原子的烷基；(f) Aminoindazolones represented by the following formula:

Wherein, R is hydrogen or an alkyl group with 1-14 carbon atoms;

(g) Aminomercaptotriazole represented by the following formula: Wherein, R may not exist or be selected from alkyl, alkenyl, aralkyl or aryl C ₁ -C ₁₀ linear or branched chain hydrocarbon groups;

(h) Aminobacid represented by the following formula: Wherein, R is hydrogen or an alkyl or alkoxy group having 1-14 carbon atoms;

(i) aminoalkylimidazoles, such as 1-(2-aminoethyl)imidazole, 1-(3-aminopropyl)imidazole; and

(j) Aminoalkylmorpholines, such as 4-(3-aminopropyl)morpholine.

Particularly preferred polyamines for use in the present invention are N-arylphenylenediamines, more particularly N-phenylphenylenediamines, such as N-phenyl-1,4-phenylenediamine, N-phenyl-1 , 3-phenylenediamine and N-phenyl-1,2-phenylenediamine.

It is preferred that the polyamine contains only one primary amine group in order to avoid coupling and/or gelling of the olefin copolymer.

The reaction between the polymer matrix intermediate product on which the carboxylic acid acylation function has been grafted and the specified polyamine compound is preferably carried out as follows: the solution of the polymer matrix is heated under inert conditions, and then generally under mixing conditions The reaction is carried out by adding a polyamine compound to the heated solution. Typically an oil solution of the polymer matrix heated to 140-175°C is used while maintaining the solution under a blanket of nitrogen. The polyamine compound is added to the solution and reacted under the specified conditions.

Generally, the polyamine compound is dissolved in a surfactant and added to a mineral lubricating oil or a synthetic lubricating oil or a solvent solution containing the acylated olefin copolymer. The solution was heated with stirring at a temperature in the range of 120-200°C under an inert gas purge as described in U.S. Patent 5,384,371, which is hereby incorporated by reference. The reaction is usually carried out in a stirred reactor under a nitrogen purge. However, it is also possible to feed the surfactant solution of the polyamine compound to a region downstream of the grafting reaction-discharging region of the twin-screw extrusion reactor.

Surfactants that can be used to effect the reaction of the acylated olefin copolymers with polyamines include, but are not limited to, those characterized by: (a) solubility characteristics compatible with mineral lubricating oils or synthetic lubricating oils, (b) ) boiling point and vapor pressure properties that do not alter the flash point of the oil and (c) polarity suitable for dissolving the polyamine. Suitable surfactants of this type include reaction products of aliphatic and aromatic hydroxy compounds with ethylene oxide, propylene oxide or mixtures thereof. These surfactants are commonly referred to as aliphatic or phenolic alkoxylates. Representative examples are ^SURFONIC® N-40, N-60, L-24-5, L-46-7 (Huntsman Chemical Company), ^Neodol® 23-5 and 25-7 (Shell Chemical Company) and ^Tergitol® surface Active agent (Union Carbide). Preferred surfactants include those containing functional groups, such as -OH, capable of reacting with the acylated olefin copolymer.

The amount of surfactant used depends in part on its ability to dissolve the polyamine. Generally, the polyamine is used in a concentration of 5-40% by weight. Instead of or in addition to the concentrates discussed above, the surfactant may also be added separately so that the total amount of surfactant in the finished additive is 10% by weight or less.

The highly grafted multifunctional olefin copolymers of this invention may be incorporated into lubricating oils in any conventional manner. Thus, the highly grafted multifunctional olefin copolymer can be directly added to the lubricating oil to disperse or dissolve the copolymer in the lubricating oil at the desired concentration. Such mixtures may be added to lubricating oils at room temperature or at elevated temperatures. Alternatively, the highly grafted multifunctional olefin copolymers can be blended with suitable oil-soluble solvents/diluents (such as benzene, xylene, toluene, lubricating base oils, and petroleum fractions) to form concentrates, which are then The compound is blended with lubricating oil to obtain the final product. Such additive concentrates will typically contain (by active ingredient (A.I.)) about 3-45% by weight, preferably about 10-35% by weight, of highly grafted multifunctional olefin copolymer additives and typically About 20-90% by weight, preferably about 40-60% by weight base oil (by weight of the concentrate).

The primary utility of the highly grafted multifunctional olefin copolymer products of the present invention is found in lubricating oil compositions using base oils where the additives are either dissolved or dispersed. These base oils may be natural or synthetic base oils or mixtures thereof. Base oils suitable for use in preparing the lubricating oil compositions of the present invention include those base oils commonly used 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 can also be obtained using the additive mixture of the present invention in base oils conventionally used and/or suitable for use as power transmission fluids, heavy duty hydraulic fluids, hydraulic steering fluids, and the like. It may also be advantageous to incorporate the additive compositions of the present invention in gear oils, industrial lubricating oils, pump lubricating oils and other lubricating oil compositions.

These lubricating oil formulations often contain additional additives that will provide the desired properties of these formulations. Among these types of additives are additional viscosity index improvers, antioxidants, preservatives, detergents, dispersants, depressants, antiwear agents, foam suppressors, demulsifiers, and friction modifiers.

In preparing lubricating oil formulations, the additives are generally incorporated as 10-80% by weight active ingredient concentrates in hydrocarbon oils such as mineral lubricating oils or other suitable solvents. Typically these concentrates may be diluted with 3-100, eg 5-40 parts by weight of lubricating oil per part by weight of the additive component to form a finished lubricant such as a crankcase oil. The purpose of the concentrate is, of course, to enable handling of various difficult materials, as well as to facilitate dissolution or dispersion in the final blend. Thus, the highly grafted multifunctional olefin copolymers are generally used in the form of 10-50% by weight concentrates, for example in lubricating oil fractions.

The highly grafted multifunctional olefin copolymers of the present invention will generally be used in admixture with lubricating base oils containing oils of lubricating viscosity including natural lubricating oils, synthetic lubricating oils and mixtures thereof.

Natural oils include animal and vegetable oils (eg, castor oil, lard), liquid petroleum and hydrorefined, solvent-treated or acid-treated paraffin-based, naphthenic and mixed paraffin-naphthenic mineral oils. Oils of lubricating viscosity derived from coal or oil shale can also be used as base oils. Synthetic lubricating oils useful in the present invention include any of a wide variety of oils commonly used in synthetic lubricating oils including, but not limited to, polyalphaolefins, alkylated aromatics, alkylene oxide polymers, Copolymers, copolymers and their mixtures, in which the terminal hydroxyl groups have been modified by esterification, etherification, etc., esters of dicarboxylic acids and silicone-based oils.

The present invention also relates to a method of improving the fuel economy and fuel economy life of an automobile, wherein said method comprises adding the lubricating oil composition described above to the crankcase of the automobile and driving it.

Also, consider a way to extend the drain interval of the lubricant in your car. The method comprises adding the lubricating oil composition described above to the crankcase of an automobile and driving it.

Methods of improving the low temperature performance of lubricating oils are also considered. Said process involves mixing an oil of lubricating viscosity with the highly grafted multifunctional olefin copolymer described above.

The highly grafted multifunctional olefin copolymers of the present invention can be post-treated to provide additional properties required for specific lubricant applications. Workup techniques are well known in the art and include borylation, phosphorylation and maleation.

The following examples illustrate the preparation of the highly grafted multifunctional olefin copolymers of the present invention.

Embodiment 1 (preparation highly grafted (0.36 carboxyl/1000Mn) multifunctional viscosity modifier)

The same general procedure was used to prepare the multifunctional hydrocarbon copolymers described in the following examples. Acylated ethylene-propylene copolymers were prepared by free-radical grafting of maleic anhydride onto the ethylene-propylene copolymer backbone in the presence of solvent. The number average molecular weight of the acylated ethylene-propylene copolymer was about 40,000 as determined by gel permeation chromatography. The reaction conditions and the molar ratio of maleic anhydride to ethylene-propylene copolymer were such that 7.2 moles of maleic anhydride were grafted onto the backbone of the olefin copolymer. To form the acylated ethylene-propylene copolymer, this corresponds to a polymer backbone of 0.36 carboxyl groups/1000 Mn (ie 2 x 7.2 = 14.4 carboxyl groups/40,000 Mn = 0.36 carboxyl groups/1000 Mn). The acylated ethylene-propylene copolymer was reacted with N-phenyl-1,4-phenylenediamine (NPPDA) in the presence of a surfactant at 160°C for about 6 hours. The NPPDA is added in an amount sufficient to theoretically react with all grafted carboxyl groups.

Embodiment II (preparation of highly grafted (0.71 carboxyl/1000Mn) multifunctional viscosity modifier)

Using the same method as in Example 1, the highly grafted multifunctional viscosity modifier of Example 2 was prepared. However, sufficient maleic anhydride was added so that 14.2 moles of maleic anhydride were grafted onto the backbone of the olefin copolymer. To form the acylated ethylene-propylene copolymer, this corresponds to a polymer backbone of 0.71 carboxyl groups/1000 Mn (ie 2 x 14.2 = 28.4 carboxyl groups/40,000 Mn = 0.71 carboxyl groups/1000 Mn). The acylated ethylene-propylene copolymer was reacted with N-phenyl-1,4-phenylenediamine (NPPDA) in the presence of a surfactant at 160°C for about 6 hours. The NPPDA is added in an amount sufficient to theoretically react with all grafted carboxyl groups.

Comparative example 1 (preparation has the multifunctional viscosity improver of 0.16 carboxyl group/1000Mn)

With the same method as Example 1, the multifunctional viscosity modifier of Comparative Example 1 was prepared. However, sufficient maleic anhydride was added so that 3.2 moles of maleic anhydride were grafted onto the backbone of the olefin copolymer. To form the acylated ethylene-propylene copolymer, this corresponds to a polymer backbone of 0.16 carboxyl groups/1000 Mn (ie 2 x 3.2 = 6.4 carboxyl groups/40,000 Mn = 0.16 carboxyl groups/1000 Mn). The acylated ethylene-propylene copolymer was reacted with N-phenyl-1,4-phenylenediamine (NPPDA) in the presence of a surfactant at 160°C for about 6 hours. The NPPDA is added in an amount sufficient to theoretically react with all grafted carboxyl groups.

Table 1 illustrates the enhanced properties obtained by using the highly grafted multifunctional olefin copolymers of the present invention. Example A, containing the olefin copolymer of Example 1, and Comparative Example A, containing a multifunctional viscosity modifier prepared according to WO-A-94/13763, available from Exxon Chemical Company, by adding the viscosity modifier separately The products of Example A and Comparative Example A were prepared into the same lubricating oil formulation containing SAE 15W-50 motor oil with the same detergent inhibitor component, mineral oil base stock and ashless dispersant. These fully formulated oils were tested in the Peugeot XUD 11ATE test and the results are given in Table 1. The Peugeot XUD 11ATE test illustrates the effect of additives on viscosity control in passenger car diesel engines. Table 1 Test results test ACEA level Example A Comparative Example A B2 B3 piston indicator 42min 46min 50.0 40.9 viscosity increase 200max 125max 20 214 sludge R&R R&R 9.2 7.6 performance B3 fail

From the results in Table 1 it is evident that in the XUD 11ATE test the fully formulated oil (Example 1) containing the viscosity index improver of the present invention achieved the highest performance (i.e. B3), whereas in this test , a fully formulated oil (Comparative Example A) containing a commercially available multifunctional viscosity modifier failed. This data demonstrates the clear and unexpected advantages of the viscosity modifiers of the present invention for viscosity control in passenger car diesel engines. This viscosity control has the following continuing benefits for the lubricant: improved pumpability, improved wear, improved fuel economy, and improved extended oil drain intervals.

Table 2 illustrates the enhanced properties obtained by using the highly grafted multifunctional olefin copolymers of the present invention. Example B, containing the olefin copolymer of Example 1, and Comparative Example B, containing a multifunctional viscosity modifier prepared according to WO-A-94/13763, available from Exxon Chemical Company, by separately adding the viscosity modifier to The products of Example B and Comparative Example B were prepared in the same lubricating oil formulation containing SAE 10W-40 motor oil with the same detergent inhibitor component, mineral oil base stock and ashless dispersant. These fully formulated oils were tested in the Peugeot TU3M HTPD test and the results are presented in Table 2. The Peugeot TU3M HTPD test illustrates the effect of additives on viscosity control and high temperature precipitation in passenger car gasoline engines.

Table 2 TU3MHTPD results test ACEA level Example B Comparative Example B A2 A3 Piston ring bonding >9.0 >9.0 9.8 9.3 Piston ring adhesion > 9.0 0max 0max 0 2 Piston paint film >60 >65 81.6 61.5 viscosity increase <40 <40 39.3 15.0 performance A3 fail

From the results in Table 2 it is evident that in the TU3M HTPD test, the fully formulated oil (Example 1) containing the viscosity index improver of the present invention achieved the highest performance (i.e. A3), whereas in this test , a fully formulated oil (Comparative Example B) containing a commercially available multifunctional viscosity modifier failed. This data demonstrates the clear and surprising advantages of the highly grafted multifunctional viscosity modifiers of the present invention for viscosity control and high temperature piston deposition. The good performance in this test demonstrates that the improved wear protection in long drain intervals and the ability to increase extended drain intervals, compared to similar formulations containing viscosity modifiers outside the scope of the present invention, is due to the smaller Ring and wire frayed.

Table 3 illustrates VE sludge and varnish and cold start simulator (CCS) results. The highly grafted multifunctional viscosity modifier of Example 1 and the comparative viscosity modifier were respectively added to the same lubricating oil formulation containing SAE 10W-30 mineral oil base oil with the same detergent inhibitor component. 4% by weight of a commercially available Mannich dispersant was added to the comparative oil, while only 2% by weight of Mannich dispersant was added to the oil of Example C, the oil of Example C Contains the viscosity improver prepared in Example 1. The comparative viscosity modifier present in Comparative Example C was prepared as described above for Comparative Example I so as to provide 0.16 carboxyl groups, ie 0.08 moles of maleic anhydride, per 1000 Mn of the copolymer matrix. Comparative Example C contained 0.84% of the copolymer matrix from the comparative viscosity modifier, while Example C contained the viscosity index improver of the present invention with 0.91% of the copolymer matrix from the viscosity modifier of Example 1. The reduction in low temperature viscosity as indicated by the cold start simulator test is the result of the significant reduction (2 vs. 4%) in dispersant volume allowed by the exceptional dispersant properties of the highly grafted multifunctional viscosity modifier of Example 1 direct result. table 3 Example C Comparative Example C CCS 20°C 3020 3300 Average sludge (9.0 minutes) 9.23 9.32 Average film (5.0 minutes) 6.31 6.07

From the above data it is evident that compositions containing viscosity modifiers of the present invention are compared to compositions containing viscosity modifiers outside the scope of the present invention, even though the viscosity modifiers of the present invention only contain Half the amount of Mannich dispersant and the oil of the viscosity modifier of Comparative Example 1 also showed comparable VE sludge and varnish. In addition, it is evident that oils containing viscosity modifiers of the present invention exhibit improved (ie reduced) CCS as compared to similar oils containing viscosity modifiers outside the scope of the present invention. From this improvement in low temperature performance, one can formulate lubricating oil compositions containing little or even no unconventional, i.e., synthetic oils, such as polyalphaolefins, and still meet the stated performance requirements for crankcase lubricating oils . The unexpected ability to formulate lubricating oils of the present invention using higher amounts of mineral oil without loss of performance allows for greater formulation flexibility and cost savings.

The dispersant properties of the products of the present invention are listed in Table 4 below. Dispersibility was determined using the Sludge Dispersibility Test (SDT). This test measures the ability of a dispersant to suspend and remove a thin layer of sludge with blotter paper. When using the dispersant option, the removal of the oil with the blotter forms 2 rings, the inner ring constitutes the sludge transferred by the dispersant and the outer ring includes the base oil. The effect of this dispersant is defined by the ratio of the diameter of the inner ring to the diameter of the outer ring. For a particular selection, the higher the ratio, the better the performance of the selection as a dispersant. In each test, 6% by weight of the additive was mixed with 94% of the heavily used oil from the VE engine test. The used oil, when stored overnight at 149°C, gave a dispersibility of 30-35% defined by the ratio of the diameter of the inner ring of undispersed sludge to the diameter of the outer oil ring times 100 on blotting paper.

Table 4 Sludge dispersibility test additive SDT results Comparative Example I 33 Example I 54 Example II 60

The results in Table 4 above show that the products of the present invention exhibit superior dispersion properties (ie higher SDT results) compared to additives outside the scope of the present invention.

Boundary lubrication occurs when the fluid film is thin enough that opposing metal surfaces interact with each other, and friction increases as this interaction occurs. In an engine, increased friction reduces fuel economy.

This boundary friction of the fluid can be measured using a High Frequency Reciprocating Rig (HFRR). The HFRR operates by vibrating a ball across the plate in a sample cartridge containing 1-2 ml of sample. The frequency of vibration, the path length of the ball's horizontal travel, the load applied to the ball and the test temperature can be controlled. By controlling these parameters, the boundary friction properties of fluids can be determined.

The novel polymer additives of the present invention and comparative dispersants were blended into SAE 5W-30 fully formulated motor oils. Same conditions as described in "Predicting Seq.VI and VIA Fuel Economy from Laboratory Bench Test" by C.Bovington, V.Anghel and H.A.Spikes (SAE Technical Paper 961 142), namely 4N load, 1mm path length, 20Hz frequency Under the condition of , use HFRR to measure the boundary friction performance of these fluids. The friction properties were measured at 130°C.

Table 5 illustrates the improvement in boundary friction results obtained by incorporation of the novel highly grafted multifunctional copolymers of the present invention into motor oils compared to multifunctional copolymers containing less than 0.3-0.5 carboxyl groups per 1000 Mn . As noted above, lower boundary friction results indicate improved fuel economy. The multifunctional olefin copolymer viscosity modifier used in the following examples is an ethylene-propylene copolymer with a number average molecular weight of about 40,000, which is determined by gel permeation chromatography and from the above-mentioned Example I and Comparative Example I method for the preparation of universal assay standards. Table 5 lists the moles of carboxyl groups per 1000 Mn, the amount of ethylene-propylene copolymer viscosity index improver and the boundary friction results. Examples 1-16 contained a commercially available low molecular weight olefin copolymer dispersant and the amount used in each example is also listed in the table. Examples 9-16 additionally contained 2.0% of a conventional Mannich dispersant.

All test oils are based on SAE 5W-30 fully formulated passenger car motor oils. The oil is formulated with commercially available detergents, ZDDP, antioxidants, defoamers, pour point depressants, rust inhibitors, viscosity index improvers, friction modifiers, and dilute process oils.

Table 5, Boundary Friction Results Examples# Carboxyl/1000Mn Olefin Copolymer Backbone quantity additional dispersant boundary friction 1 ^* 0.16 6.8 2.0 0.1012 2 ^* 0.16 8.0 2.0 0.0990 3 ^* 0.16 6.0 5.0 0.1003 4 ^* 0.16 8.0 5.0 0.1011 Average Boundary Friction /% Reduced by ¹ 0.1004 / 0% 5 0.36 6.0 2.0 0.0974 6 0.36 8.0 2.0 0.0974 7 0.36 6.0 5.0 0.0969 8 0.36 8.0 5.0 0.0990 Average Boundary Friction/% Reduction1 ^0.0977 /2.7% 9 ^* 0.16 6.8 2.0 0.1076 10 ^* 0.16 8.0 2.0 0.1094 11 ^* 0.16 6.0 5.0 0.1075 12 ^* 0.16 8.0 5.0 0.1084 Average Boundary Friction /% Reduced ² 0.1082 / 0% 13 0.36 6.0 2.0 0.1052 14 0.36 8.0 2.0 0.1047 15 0.36 6.0 5.0 0.1050 16 0.36 8.0 5.0 0.1053 Average Boundary Friction/% Reduction ² 0.1050/2.9% 17 ^* 0.16 8.0 0 0.1090 18 0.36 8.0 0 0.1035 % Lower ³ 5.0% ^* Comparative Example 1: Percentage reduction in boundary friction compared to oils containing lower degrees of grafting, Examples 1-42: Percentage reduction in boundary friction compared to oils containing lower degrees of grafting, Examples 9-123: Compared to oils containing lower degrees of grafting Percent Boundary Friction Reduction for the Oil of Example 17 vs. the Oil of Example 18

From the data in the table above it is evident that the oil composition (Examples 1-4, 9-12 and 17) In comparison, the highly grafted multifunctional olefin copolymers (Examples 5-8, 13-16 and 18) containing the present invention showed improved (i.e. reduced) boundary friction, which indicated improved economy.

The invention is susceptible to considerable variation in practice. Therefore, the present invention is not limited to the specific embodiments described above. Rather, the present invention includes the legal equivalents within the spirit and scope of the appended claims.

The patentee does not intend to dedicate all disclosed embodiments to the public, nor does he intend to make any disclosed improvements and changes that do not literally fall within the scope of the claims, and they are considered to be the subject of the present invention under the principle of equivalent part of the invention.

Claims (13)

1. A highly grafted multifunctional olefin copolymer viscosity modifier, which contains the reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer contains an olefin copolymer, on which 0.3-0.75 carboxyl groups are grafted per 1000 number average molecular weight units of the olefin copolymer, and the number average molecular weight of the olefin copolymer is 20000-150000. 2. The highly grafted multifunctional olefin copolymer viscosity modifier according to claim 1, wherein the olefin copolymer is a copolymer of ethylene and one or more _C3 - _C23 alpha-olefins. 3. The highly grafted multifunctional olefin copolymer viscosity modifier according to claim 1, wherein the polyamine is selected from: (a) N-arylphenylenediamine represented by the following formula: Wherein: R ¹ is hydrogen, -NH-aryl, -NH-aralkyl, -NH-alkyl, or a branched or linear group with 4-24 carbon atoms, which can be an alkyl , alkenyl, alkoxy, aralkyl, alkaryl, hydroxyalkyl or aminoalkyl; R ² is -NH ₂ , CH ₂ -(CH ₂ ) _n -NH ₂ or CH ₂ -aryl- NH ₂ , wherein n represents 1-10; R ³ is hydrogen, alkyl, alkenyl, alkoxy, aralkyl or alkaryl with 4-24 carbon atoms; (b) an aminothiazole selected from aminothiazole, aminobenzothiazole, aminobenzothiadiazole and aminoalkylthiazole; (c) Aminocarbazole represented by the following formula:

Wherein: R and R ¹ represent hydrogen, or an alkyl, alkenyl or alkoxy group with 1-14 carbon atoms; (d) Aminoindole represented by the following formula:

wherein, R represents hydrogen or an alkyl group having 1-14 carbon atoms; (e) aminopyrrole represented by the following formula:

Wherein, R is a divalent alkylene group having 2-6 carbon atoms and ^R is hydrogen or an alkyl group having 1-14 carbon atoms; (f) an aminoindazolone represented by the following formula:

wherein R is hydrogen or an alkyl group having 1 to 14 carbon atoms: (g) aminomercaptotriazole represented by the following formula:

Wherein, R can be absent or C ₁ -C ₁₀ straight chain or branched chain hydrocarbon group, selected from alkyl, alkynyl, aralkyl or aryl; (h) An amino group represented by the following formula Pyridine: Wherein, R is hydrogen or an alkyl or alkoxy group having 1-14 carbon atoms; (i) an aminoalkylimidazole selected from 1-(2-aminoethyl)imidazole and 1-(3-aminopropyl)imidazole; and (j) 4-(3-aminopropyl)morpholine. 4. an oil concentrate, by active component, it contains the carrier of 20-90% (weight) or diluent oil and the highly grafted multifunctional olefin copolymer of claim 1 of 3-45% (weight) . 5. The oil concentrate according to claim 4, further comprising at least one additive selected from the group consisting of additional viscosity index improvers, antioxidants, preservatives, detergents, dispersants, pour point depressants, antiwear agents , defoamer, demulsifier and friction modifier. 6. A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount of the highly grafted multifunctional olefin copolymer of claim 1. 7. The lubricating oil composition according to claim 6, further comprising at least one additive selected from the group consisting of additional viscosity index improvers, antioxidants, preservatives, detergents, dispersants, decontamination agents, antiwear Agents, defoamers, demulsifiers and friction modifiers. 8. The lubricating oil composition according to claim 6, wherein the oil of lubricating viscosity is selected from natural oils, synthetic oils and mixtures thereof. 9. A method of improving the fuel economy of an automobile, wherein said method comprises adding and operating the lubricating oil composition of claim 6 to the crankcase of the automobile. 10. A method of improving the fuel economy durability of an automobile, wherein said method comprises adding and operating the lubricating oil composition of claim 6 to the crankcase of the automobile. 11. A method of extending lubricant drain intervals in an automobile, wherein said method comprises adding and operating the lubricating oil composition of claim 6 to the crankcase of the automobile. 12. A method of improving the low temperature properties of a lubricating oil, said method comprising mixing an oil of lubricating viscosity with the highly grafted multifunctional olefin copolymer of claim 1. 13. A method of lubricating an automobile engine, wherein said method comprises adding the lubricating oil composition of claim 6 to the crankcase of said automobile engine and operating.