US 5,356,552 AGrant
Chlorine-Free Lubricating Oils Having Modified High Molecular Weight Succinimides
Issue Date:1994-10-18
•74 Claims
Abstract
Alkenyl or alkyl succinimide additives which are the reaction product of a high molecular weight alkenyl- or alkyl-substituted succinic anhydride and a polyalkylene polyamine having an average of greater than 4 nitrogen atoms per mole, wherein the reaction product is post-treated with a cyclic carbonate, are compatible with fluoroelastomer engine seals and, for concentration levels at which fluoroelastomer seal compatibility is achieved, possess improved dispersancy and/or detergency properties when employed in chlorine-free lubricating oils.
Metadata
Assignee
- Chevron Research and Technology Company, A Division of Chevron U.S.A. Inc.
Inventors
- James J. Harrison
- William R. Ruhe, Jr.
- Jack E. Morris
- Jacques Cazin
Application Information
Application Number:US 1350951
Filing Date:1993-10-12
Priority Date:1993-03-09
Art Unit:111
Classifications
IPC:
C10M13344
Field of Search:
25251.5 A;51.5 R
Patent Drawings
This patent does not have any drawings.
Description
FIELD OF THE INVENTION
This invention relates to chlorine-free lubricating oils having additives which are compatible with fluoroelastomer seals. In particular, this invention is directed toward a lubricating oil having modified polyamino alkenyl or alkyl succinimides which are the reaction product of an alkenyl- or alkyl-substituted succinic anhydride and a polyalkylene polyamine, wherein the reaction product is post-treated with a cyclic carbonate. The modified polyamino alkenyl or alkyl succinimides of this invention have been found to be compatible with fluoroelastomer seals and, for concentration levels at which fluoroelastomer seal compatibility is achieved, to possess improved dispersancy and/or detergency properties when employed in a lubricating oil.
BACKGROUND OF THE INVENTION
It is known in the art that alkenyl- or alkyl-substituted succinic anhydrides have been used as dispersants and/or detergents in lubricating oils and fuels. Such alkenyl- or alkyl-substituted succinic anhydrides have been prepared by three well-known processes: a thermal process (see, e.g., U.S. Pat. No. 3,361,673), a chlorination process (see, e.g., U.S. Pat. No. 3,172,892) and a combination of the thermal and chlorination processes (see, e.g., U.S. Pat. No. 3,912,764). The polyisobutenyl succinic anhydride ("PIBSA") produced by the thermal process has been characterized as a monomer containing a double bond in the product. Although the exact structure of chlorination PIBSA has not been definitively determined, the chlorination process PIBSA materials have been characterized as monomers containing either a double bond, a ring other than succinic anhydride ring and/or chlorine in the product. [(See J. Weill and B. Sillion, "Reaction of Chlorinated Polyisobutene with Maleic Anhydride: Mechanism Catalysis by Dichloramaleic Anhydride," Revue de I'Institut Francais du Petrole, Vol. 40, No. 1, pp. 77-89 (January-February, 1985).] Such compositions include one-to-one monomeric adducts (see, e.g., U.S. Pat. Nos. 3,219,666; 3,381,022) as well as "multiply adducted" products, adducts having alkenyl-derived substituents adducted with at least 1.3 succinic groups per alkenyl-derived substituent (see, e.g., U.S. Pat. No. 4,234,435).
Alkenyl or alkyl succinimides formed by the reaction of an alkenyl- or alkyl-substituted succinic anhydride and a polyamine are also well known as lubricating oil dispersant and/or detergent additives. See, e.g., U.S. Pat. Nos. 3,361,673 and 3,018,250.
As taught in U.S. Pat. No. 4,612,132 ("the '132 patent"), alkenyl or alkyl succinimides may be modified such that one or more of the nitrogens of the polyamine moiety is substituted with a hydrocarbyl oxycarbonyl, a hydroxyhydrocarbyl oxycarbonyl or a hydroxy poly(oxyalkylene) oxycarbonyl. These modified succinimides, which impart improved dispersancy and/or detergency properties when employed in lubricating oils, are obtained by reacting the product of an alkyl or alkenyl succinic anhydride and a polyamine with a cyclic carbonate, a linear mono- or poly carbonate, or a chloroformate. The '132 patent discloses succinimide alkenyl or alkyl groups containing from 10 to 300 carbon atoms; most preferred are alkenyl or alkyl groups having from 20 to 100 carbon atoms. However, the highest molecular weight alkenyl or alkyl group specifically taught in the Examples has a molecular weight of 1300. Furthermore, the '132 patent fails to teach anything about the fluoroelastomer seal compatibility of the modified succinimides it discloses.
U.S. Pat. No. 4,747,965 discloses modified succinimides similar to those disclosed in the '132 patent, except that the modified succinimides disclosed in this patent are derived from succinimides having an average of greater than 1.0 succinic groups per alkenyl-derived substituent.
While it is known in the art that succinimide additives useful in controlling engine deposits may be substituted with alkenyl or alkyl groups ranging in number average molecular weight ("Mn") from approximately 300 to 5000, no reference teaches that substituents having a Mn of 2000-2700 perform better than those having a Mn of about 1300. Two references which discuss the effect of the alkenyl-derived substituent's molecular weight on the performance of succinimides as lubricating oil additives are "The Mechanism of Action of Polyisobutenyl Succinimide Lubricating Oil Additives", by E. S. Forbes and E. L. Neustadter (Tribology, Vol. 5, No. 2, pp. 72-77 (April, 1972), and U.S. Pat. No. 4,234,435 ("the '435 patent").
The Forbes and Neustadter article discusses, in part, the effect of polyisobutenyl Mn on the detergency properties of a polyisobutenyl succinimide. However, as shown in FIG. 1 on page 76 of their article, the results of the tests Forbes and Neustadter conducted indicate that succinimides having a 1300 Mn polyisobutenyl substituent are more effective as detergents than those having a polyisobutenyl substituent with a Mn of 2000 or greater. In showing the effect of polyisobutenyl molecular weight on succinimide detergency, this article teaches that maximum detergency performance is obtained when the polyisobutenyl group has a Mn of about 1300.
The '435 patent teaches a preferred polyalkene-derived substituent group with a Mn in the range of 1500-3200. For polybutenes, an especially preferred Mn range is 1700-2400. However, the '435 patent also teaches that the succinimides must have a succinic ratio of at least 1.3, that is at least 1.3 succinic groups per equivalent weight of polyalkene- derived substituent group. Most preferred are succinimides having a succinic ratio of 1.5-2.5. The '435 patent teaches that succinimides must have both a high Mn polyalkylene-derived substituent and a high succinic ratio.
The succinimide additives disclosed in the '435 patent are not only dispersants and/or detergents, but also viscosity index improvers. That is, the '435 additives impart fluidity modifying properties to lubricant compositions containing them. However, viscosity index improving properties are not always desirable for the succinimide, as in the case of single-grade oil formulations, for example. In addition, the succinimide additives disclosed in the '435 patent all contain chlorine, which is undesirable from an environmental point of view.
Polyamino alkenyl or alkyl succinimides and other additives useful as dispersants and/or detergents, such as Mannich bases, contain basic nitrogen. While basicity is an important property to have in the dispersant/detergent additive, it is believed that the initial attack on fluoroelastomer seals used in some engines involves attack by the basic nitrogen. This attack leads to dehydrofluorination, and eventually results in cracks in the seals and loss of other desirable physical properties in the elastomer.
One approach towards solving the elastomer problem is described in U.S. Pat. No. 4,873,009 to Ronald L. Anderson. This patent is also concerned, in part, with the use of succinimides as lube oil additives. Anderson recognizes in Col. 2, lines 28 et seq. that lube additives prepared from "long chain aliphatic polyamines", i.e., succinimides, "are excellent lube oil additives". Anderson teaches such succinimides are "inferior to additives where the alkylene polyamine is hydroxyalkylated" (Col. 2, lines 31-32). Such hydroxyalkylated polyamine- based succinimides, however, "have the drawback that they tend to attack engine seals particularly those of the fluorocarbon polymer type" (Col. 2, lines 35-37).
Anderson solves his fluoroelastomer polymer seal compatibility problem by directly borating his hydroxyalkylated polyamine based succinimides. Furthermore, according to Anderson, it would be desirable for the additive to have a relatively high concentration of N-hydroxyalkyl moieties because the more N-hydroxyalkyl substituents, the cleaner the engine. However, Anderson also teaches that the more amino groups in the polyamine, the greater the degradation of fluoroelastomer seal, and that alkylene amines containing more than 2 amino groups cannot be utilized (Col. 2, lines 50-62).
Accordingly, there exists a need in the art for a succinimide lubricating oil additive which is effective in controlling engine deposits, but which does not require boration to achieve fluoroelastomer seal compatibility.
Coupled with the increasingly severe performance requirements is the issue of heightened environmental concerns. Formulations must therefore avoid the use of potentially harmful elements.
At present, engine oils are formulated to meet the established performance requirements (e.g. API, CCMC, OEM), as well as, satisfying most environmental concerns. But, the removal of elements such as chlorine, and phosphorous have been not been fully achievable.
SUMMARY OF THE INVENTION
A unique class of modified polyamino alkenyl or alkyl succinimide compounds has now been found to be simultaneously compatible with fluoroelastomer seals and, at concentration levels for which fluoroelastomer seal compatibility is achieved, effective in controlling engine deposits. These modified polyamino alkenyl or alkyl succinimides are prepared from the succinimide reaction product of (1) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of about 2000 to about 2700 and a weight average molecular weight (Mw) to Mn ratio of about 1 to about 5; and (2) a polyalkylene polyamine having greater than 4 nitrogen atoms per mole. The modified succinimides of the present invention are obtained by post-treating the succinimide reaction product with a cyclic carbonate. This unique class of modified polyamino alkenyl or alkyl succinimide compounds can be used in a lubricating oil composition that is essentially free of chlorine.
That lubricating oil composition can have, in addition to the succinimide, a succinate ester of substantially saturated polymerized olefin-substituted succinic acid and aliphatic polyhydric alcohol; detergents such as metal sulfonates, metal alkyl phenates, metal salicylates, and mixtures thereof; and zinc dialkyldithiophosphate. By "essentially free of chlorine", we mean that the level of chlorine in the lubricating oil composition is less than 50 ppm.
Among other factors, the present invention is based on the finding that a unique class of succinimides is effective in controlling engine deposits at concentration levels for which the succinimides are simultaneously compatible with engine fluoroelastomer seals. Generally, known succinimides useful as dispersants and/or detergents are not always compatible with fluoroelastomer seals when present in lubricating oil compositions at concentration levels necessary to be effective in controlling engine deposits. Accordingly, the present invention also relates to a chlorine-free lubricating oil composition containing these modified polyamino alkenyl or alkyl succinimides.
Among other factors, the present invention is also based on the finding that a chlorine-free lubricating oil composition having a unique class of modified polyamino alkenyl or alkyl succinimides wherein the alkenyl or alkyl substituent has a Mn in the range of from 2000 to 2700 possess both superior fluoroelastomer seal compatibility and superior dispersancy and/or detergency properties compared to those wherein the alkenyl or alkyl substituent has a Mn of less than about 2000. This succinimide dispersant is used in combination with a second low chlorine dispersant and a blend of detergents that includes a low overbased sulfonate, a Mg high overbased sulfonate, and a phenate. The composition also comprises zinc dithiophospate and inhibitors.
This composition has numerous advantages over previous compositions. Those advantages include improved deposit control, improved oxidation stability, improved fluoroelastomer compatibility, acceptable rheological properties, and low chlorine.
DETAILED DESCRIPTION OF THE INVENTION
The lubricating oil composition of this invention has a chlorine level below 50 ppm. That lubricating oil composition contains a base oil and a modified polyamino alkenyl or alkyl succinimides.
THE BASE OIL
The base oil used with the additive compositions of this invention may be mineral oil or synthetic oils of lubricating viscosity and preferably suitable for use in the crankcase of an internal combustion engine. The lubricating oils may be derived from synthetic or natural sources. Mineral oil for use as the base oil in this invention includes paraffinic, naphthenic and other oils that are ordinarily used in lubricating oil compositions. Synthetic oils include both hydrocarbon synthetic oils and synthetic esters. Useful synthetic hydrocarbon oils include liquid polymers of alpha olefins having the proper viscosity. Especially useful are the hydrogenated liquid oligomers of C.sub.6 to C.sub.12 alpha olefins such as 1-decene trimer. Likewise, alkyl benzenes of proper viscosity such as didodecyl benzene can be used. Useful synthetic esters include the esters of both monocarboxylic acid and polycarboxylic acids as well as monohydroxy alkanols and polyols. Typical examples are didodecyl adipate, pentaerythritol tetracaproate, di-2-ethylhexyl adipate, dilaurylsebacate and the like. Complex esters prepared from mixtures of mono and dicarboxylic acid and mono and dihydroxy alkanols can also be used.
Blends of hydrocarbon oils with synthetic oils are also useful. For example, blends of 10 to 25 weight percent hydrogenated 1-decene trimer with 75 to 90 weight percent 150 SUS (100.degree. F.) mineral oil gives an excellent lubricating oil base.
MODIFIED POLYAMINO ALKENYL OR ALKYL SUCCINIMIDES
The modified polyamino alkenyl or alkyl succinimides of this invention are prepared by post-treating a polyamino alkenyl or alkyl succinimide with a cyclic carbonate. The polyamino alkenyl or alkyl succinimides are typically prepared by reaction of an alkenyl or alkyl succinic anhydride with a polyamine. It is thought that this dispersant is instrumental in producing the better deposit control, better oxidation stability, and better fluoroelastomer stability.
Alkenyl or alkyl succinimides are disclosed in numerous references and are well known in the art. Certain fundamental types of succinimides and related materials encompassed by the term of art "succinimide" are taught in U.S. Pat. Nos. 2,992,708; 3,018,291; 3,024,237; 3,100,673; 3,219,666; 3,172,892; and 3,272,746, the disclosures of which are hereby incorporated by reference. The term "succinimide" is understood in the art to include many of the amide, imide and amidine species which are also formed by this reaction. The predominant product, however, is succinimide and this term has been generally accepted as meaning the product of a reaction of an alkenyl- or alkyl-substituted succinic acid or anhydride with a polyamine.
THE SUCCINIC ANHYDRIDE REACTANT
A thermal process for the preparation of alkenyl- or alkyl-substituted succinic anhydride involving the reaction of a polyolefin and maleic anhydride has been described in the art. This thermal process is characterized by the thermal reaction of a polyolefin with maleic anhydride. Alternatively, the alkenyl- or alkyl-substituted succinic anhydride may be prepared as described in U.S. Pat. Nos. 4,388,471 and 4,450,281, which are totally incorporated herein by reference. Other examples of the preparation of alkenyl- or alkyl-substituted succinic anhydride are taught in U.S. Pat. Nos. 3,018,250 and 3,024,195, which are totally incorporated herein by reference. It is essential that the alkenyl or alkyl-substituted succinic anhydride be prepared in the absence of chlorine so that the final product has less than 50 ppm chlorine.
In the case of the unique class of polyamino alkenyl or alkyl succinimide compounds of this invention, the alkenyl or alkyl succinic anhydride reactant is derived from a polyolefin having a Mn from about 2000 to about 2700 and a Mw/Mn ratio of about 1 to about 5. In a preferred embodiment, the alkenyl or alkyl group of the succinimide has a Mn value from about 2100 to about 2400. Most preferred are alkenyl or alkyl substituents having a Mn of about 2200.
Suitable polyolefin polymers for reaction with maleic anhydride include polymers comprising a major amount of C.sub.2 to C.sub.5 monoolefin, e.g., ethylene, propylene, butylene, iso-butylene and pentene. The polymers can be homopolymers such as polyisobutylene as well as copolymers of 2 or more such olefins such as copolymers of: ethylene and propylene, butylene, and isobutylene, etc. Other copolymers include those in which a minor amount of the copolymer monomers, e.g., 1 to 20 mole percent, is a C.sub.4 to C.sub.8 nonconjugated diolefin, e.g., a copolymer of isobutylene and butadiene or a copolymer of ethylene, propylene and 1,4-hexadiene,etc.
A particularly preferred class of olefin polymers for reaction with maleic anhydride comprises the polybutenes, which are prepared by polymerization of one or more of 1-butene, 2-butene and isobutene. Especially desirable are polybutenes containing a substantial proportion of units derived from isobutene. The polybutene may contain minor amounts of butadiene which may or may not be incorporated in the polymer. These polybutenes are readily available commercial materials well known to those skilled in the art. Disclosures thereof will be found, for example, in U.S. Pat. Nos. 3,215,707; 3,231,587; 3,515,669; 3,579,450; and 3,912,764, as well as U.S. Pat. Nos. 4,152,499 and 4,605,808. The above are incorporated by reference for their disclosures of suitable polybutenes.
Suitable succinic anhydride reactants also include copolymers having alternating polyalkylene and succinic groups, such as those taught in U.S. Pat. No. 5,112,507, which is hereby incorporated by reference.
As used herein, the term "succinic ratio" refers to the average number of succinic groups per polyolefin group in the alkenyl or alkyl succinic anhydride reaction product of maleic anhydride and polyolefin. For example, a succinic ratio of 1.0 indicates an average of one succinic group per polyolefin group in the alkenyl or alkyl succinic anhydride product. Likewise, a succinic ratio of 1.35 indicates an average of 1.35 succinic groups per polyolefin group in the alkenyl or alkyl succinic anhydride product, and so forth.
The succinic ratio can be calculated from the saponification number (mg KOH per gram of sample), the actives content of the alkenyl or alkyl succinic anhydride product and the molecular weight of the starting polyolefin. The actives content of the alkenyl or alkyl succinic anhydride product is measured in terms of the actives fraction, wherein an actives fraction of 1.0 is equivalent to 100 weight percent actives. Accordingly, an actives fraction of 0.5 would correspond to 50 weight percent actives.
The succinic ratio of the alkenyl or alkyl succinic anhydride product of maleic anhydride and polyolefin can be calculated in accordance with the following equation: ##EQU1## wherein P=saponification number of the alkenyl or alkyl succinic anhydride sample (mg KOH/g)
A=actives fraction of the alkenyl or alkyl succinic anhydride sample
M.sub.po =number average molecular weight of the starting polyolefin
M.sub.ma =98 (molecular weight of maleic anhydride)
C=conversion factor=112220 (for conversion of gram-moles of alkenyl or alkyl succinic anhydride per gram of sample to milligrams of KOH per gram of sample)
The saponification number, P, can be measured using known procedures, such as the procedure described in ASTM D94.
The actives fraction of the alkenyl or alkyl succinic anhydride can be determined from the percent of unreacted polyolefin according to the following procedure. A 5.0 gram sample of the reaction product of maleic anhydride and polyolefin is dissolved in hexane, placed in a column of 80.0 grams of silica gel (Davisil 62, a 140 angstrom pore size silica gel), and eluted with 1 liter of hexane. The percent unreacted polyolefin is determined by removing the hexane solvent under vacuum from the eluent and weighing the residue. Percent unreacted polyolefin is calculated according to the following formula: ##EQU2##
The weight percent actives for the alkenyl or alkyl sucinic anhydride product is calculated from the percent unreacted polyolefin using the formula: ##EQU3##
The actives fraction of the alkenyl or alkyl succinic anhydride is then calculated as follows: ##EQU4##
The percent conversion of polyolefin is calculated from the weight percent actives as follows: ##EQU5## wherein M.sub.po =number average molecular weight of the starting polyolefin
M.sub.ma =98 (molecular weight of maleic anhydride)
SR=succinic ratio of alkenyl or alkyl succinic anhydride product
It is, of course, understood that alkenyl or alkyl succinic anhydride products having high succinic ratios can be blended with other alkenyl succinic anhydrides having lower succinic ratios, for example, ratios of around 1.0, to provide an alkenyl succinic anhydride product having an intermediate succinic ratio.
In general, suitable succinic ratios for the alkenyl or alkyl succinic anhydride reactants employed in preparing the additives of this invention are greater than about 1 but less than about 2. Succinic anhydrides with succinic ratios of about 2, when reacted with amines having greater than 4 nitrogen atoms per mole and post-treated with a cyclic carbonate, form gels. Accordingly, succinic ratios of about 1.7 or less are preferred.
Processes for producing a succinimide additive that has a succinic ratio of about 1.7 or less are disclosed in U.S. Ser. No. 918,990, filed Jul. 23, 1992, entitled "Two-Step Thermal Process for the Preparation of Alkyenyl Succinic Anhydride"; U.S. Ser. No. 918,180, filed Jul. 23, 1992, entitled "Two-Step Free Radical Catalyzed Process for the Preparation of Alkyenyl Succinic Anhydride"; and U.S. Ser. No. 919,342, filed Jul. 23, 1992, entitled "One-Step Process for the Preparation of Alkyenyl Succinic Anhydride"; which are totally incorporated herein by reference.
THE POLYAMINE REACTANT
The polyamine to be reacted with the alkenyl or alkyl succinic anhydride in order to produce the polyamino alkenyl or alkyl succinimide employed in this invention is generally a polyalkylene polyamine. Preferably, the polyalkylene polyamine has an average nitrogen atom to molecule ratio of greater than 4.0, up to a maximum of about 12. Most preferred are polyamines having an average nitrogen atom to molecule ratio of from about 5 to about 7. The average nitrogen atom to molecule ratio is calculated as follows: ##EQU6## wherein % N=percent nitrogen in polyamine or polyamine mixture
M.sub.pa =number average molecular weight of the polyamine or polyamine mixture
Preferred polyalkylene polyamines also contain from about 4 to about 40 carbon atoms, there being preferably from 2 to 3 carbon atoms per alkylene unit. The polyamine preferably has a carbon-to-nitrogen ratio of from about 1:1 to about 10:1.
The polyamine is so selected so as to provide at least one basic amine per succinimide. Since the reaction of the polyamino alkenyl or alkyl succinimide a cyclic carbonate is believed to efficiently proceed through a primary or secondary amine, at least one of the basic amine atoms of the polyamino alkenyl or alkyl succinimide must either be a primary amine or a secondary amine. Accordingly, in those instances in which the succinimide contains only one basic amine, that amine must either be a primary amine or a secondary amine.
The polyamine portion of the polyamino alkenyl or alkyl succinimide may be substituted with substituents selected from (A) hydrogen, (B) hydrocarbyl groups of from 1 to about 10 carbon atoms, (C) acyl groups of from 2 to about 10 carbon atoms, and (D) monohydroxy, mononitro, monocyano, lower alkyl and lower alkoxy derivatives of (B) and (C). "Lower", as used in terms like lower alkyl or lower alkoxy, means a group containing from 1 to about 6 carbon atoms. At least one of the substituents on one of the amines of the polyamine is hydrogen, e.g., at least one of the basic nitrogen atoms of the polyamine is a primary or secondary amino nitrogen atom.
Examples of suitable polyamines that can be used to form the compounds of this invention include the following: tetraethylene pentamine, pentaethylene hexamine, and Union Carbide HPA-X heavy polyamine. Such amines encompass isomers such as branched-chain polyamines and the previously mentioned substituted polyamines, including hydrocarbyl-substituted polyamines. HPA-X heavy polyamine ("HPA-X") contains an average of approximately 6.5 nitrogen atoms per mole. A preferred polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
In addition, the polyamine used as a reactant in the production of succinimides of the present invention need not be a single compound. Instead, the polyamine may be a mixture in which one or several compounds predominate with the average composition indicated. For example, tetraethylene pentamine prepared by the polymerization of aziridine or the reaction of dichloroethylene and ammonia will have both lower and higher amine members, e.g., triethylene tetramine, substituted piperazines and pentaethylene hexamine, but the composition will be largely tetraethylene pentamine and the empirical formula of the total amine composition will closely approximate that of tetraethylene pentamine.
Other examples of suitable polyamines include admixtures of amines of various sizes, provided that the overall mixture contains greater than 4 nitrogen atoms per mole. Included within these suitable polyamines are mixtures of diethylene triamine ("DETA") and heavy polyamine. A preferred polyamine admixture reactant is a mixture containing 20% by weight DETA and 80% by weight polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5, as determined by the method described above, this preferred polyamine reactant has an average nitrogen atom to molecule ratio of 5.2.
Methods of preparation of polyamines and their reactions are detailed in Sidgewick's "The Organic Chemistry of Nitrogen," Clarendon Press, Oxford, 1966, Noller's "Chemistry of Organic Compounds," Saunders, Philadelphia, 2nd Ed., 1957; and Kirk-Othmer's "Encyclopedia of Chemical Technology," 2nd Ed., especially Volumes 2, pp. 99-116.
The reaction of a polyamine with an alkenyl or alkyl succinic anhydride to produce polyamino alkenyl or alkyl succinimides is well known in the art and is disclosed in U.S. Pat. Nos. 2,992,708; 3,018,291; 3,024,237; 3,100,673; 3,219,666; 3,172,892 and 3,272,746. The above are incorporated herein by reference for their disclosures of preparing alkenyl or alkyl succinimides.
Generally, a suitable molar charge of polyamine to alkenyl or alkyl succinic anhydride for making the compounds of this invention is from about 0.35:1 to about 0.6:1; although preferably from about 0.4:1 to about 0.5:1.
As used herein, the phrase "molar charge of polyamine to alkenyl or alkyl succinic anhydride" means the ratio of the number of moles of polyamine to the number of moles of succinic groups in the succinic anhydride reactant. The number of moles of succinic groups in the succinic anhydride reactant is determined as follows: ##EQU7## wherein P and C are as defined above.
POST-TREATMENT OF THE POLYAMINO ALKENYL OR ALKYL SUCCINIMIDE WITH A CYCLIC CARBONATE
The polyamino alkenyl or alkyl succinimides formed as described above are then reacted with a cyclic carbonate. The resulting modified polyamino alkenyl succinimide has one or more nitrogens of the polyamino moiety substituted with a hydroxy hydrocarbyl oxycarbonyl, a hydroxy poly(oxyalkylene) oxycarbonyl, a hydroxyalkylene, hydroxyalkylenepoly-(oxyalkylene), or mixture thereof. The products so produced are compatible with fluoroelastomer seals and are effective dispersant and detergent additives for lubricating oils and for fuels.
The reaction of a polyamino alkenyl or alkyl succinimide with a cyclic carbonate is conducted at a temperature sufficient to cause reaction of the cyclic carbonate with the polyamino alkenyl or alkyl succinimide. In particular, reaction temperatures of from about 0.degree. C. to about 250.degree. C. are preferred with temperatures of from about 100.degree. C. to 200.degree. C. being more preferred and temperatures of from 150.degree. C. to 180.degree. C. are most preferred.
The reaction may be conducted neat, wherein both the alkenyl or alkyl succinimide and the cyclic carbonate are combined in the proper ratio, either alone or in the presence of a catalyst (such as an acidic, basic or Lewis acid catalyst), and then stirred at the reaction temperature. Examples of suitable catalysts include, for instance, phosphoric acid, boron trifluoride, alkyl or aryl sulfonic acid, alkali or alkaline carbonate.
Alternatively, the reaction may be conducted in a diluent. For example, the reactants may be combined in a solvent such as toluene, xylene, oil or the like, and then stirred at the reaction temperature. After reaction completion, volatile components may be stripped off. When a diluent is employed, it is preferably inert to the reactants and products formed and is generally used in an amount sufficient to insure efficient stirring.
Water, which can be present in the polyamino alkenyl or alkyl succinimide, may be removed from the reaction system either before or during the course of the reaction via azeotroping or distillation. After reaction completion, the system can be stripped at elevated temperatures (100.degree. C. to 250.degree. C.) and reduced pressures to remove any volatile components which may be present in the product.
Alternatively, a continuous system may be employed in which the alkenyl or alkyl succinic anhydride and polyamine are added at the front end of the system while the organic carbonate is added further downstream in the system. In such a continuous system, the organic carbonate may be added at any time after mixing of the alkenyl or alkyl succinic anhydride with the polyamine has occurred. Preferably, the organic carbonate is added within two hours after mixing of the alkenyl or alkyl succinic anhydride with the polyamine, preferably after the major portion of the amine has reacted with the anhydride.
In a continuous system, the reaction temperature may be adjusted to maximize reaction efficiency. Accordingly, the temperature employed in the reaction of the alkenyl or alkyl succinic anhydride with a polyamine may be the same as or different from that which is maintained for the reaction of this resulting product with the cyclic carbonate. In such a continuous system, the reaction temperature is generally between 0.degree. C. to 250.degree. C.; preferably between 125.degree. C. to 200.degree. C.; and most preferably between 150.degree. C. to 180.degree. C.
The reaction of polyamino alkenyl or alkyl succinimides with cyclic carbonates is known in the art and is described in U.S. Pat. 4,612,132, which is totally incorporated herein by reference.
A particularly preferred cyclic carbonate is 1,3-dioxolan-2-one(ethylene carbonate). Ethylene carbonate is commercially available or may be prepared by methods well-known in the art.
The molar charge of cyclic carbonate employed in the post- treatment reaction is based upon the theoretical number of basic nitrogens contained in the polyamino substituent of the succinimide. Thus, when 1 equivalent of tetraethylene pentamine ("TEPA") is reacted with two equivalents of succinic anhydride, the resulting bis succinimide will theoretically contain 3 basic nitrogens. Accordingly, a molar charge of 2 would require that two moles of cyclic carbonate be added for each basic nitrogen or in this case 6 moles of cyclic carbonate for each mole of bis succinimide prepared from TEPA Mole ratios of the cyclic carbonate to the basic amine nitrogen of the polyamino alkenyl succinimide employed in the process of this invention are generally in the range of from about 1.5:1 to about 4:1; although preferably from about 2:1 to about 3:1.
As described in U.S. Pat. No. 4,612,132, cyclic carbonates may react with the primary and secondary amines of a polyamino alkenyl or alkyl succinimide to form two types of compounds. In the first instance, strong bases, including unhindered amines such as primary amines and some secondary amines, react with an equivalent of cyclic carbonate to produce a carbamic ester. In the second instance, hindered bases, such as hindered secondary amines, may react with an equivalent of the same cyclic carbonate to form a hydroxyalkyleneamine linkage. Unlike the carbamate products, the hydroxyalkyleneamine products retain their basicity.
Accordingly, the reaction of a cyclic carbonate with a polyamino alkenyl or alkyl succinimide may yield a mixture of products. When the molar charge of the cyclic carbonate to the basic nitrogen of the succinimide is about 1 or less, it is anticipated that a large portion of the primary and secondary amines of the succinimide will have been converted to hydroxy hydrocarbyl carbamic esters with some hydroxyhydrocarbylamine derivatives also being formed. As the mole ratio is raised above 1, poly(oxyalkylene) polymers of the carbamic esters and the hydroxyhydrocarbylamine derivatives are expected.
The modified succinimides of this invention can also be reacted with boric acid or a similar boron compound to form borated dispersants having utility within the scope of this invention. In addition to boric acid (boron acid), examples of suitable boron compounds include boron oxides, boron halides and esters of boric acid. Generally from about 0.1 equivalents to 10 equivalents of boron compound to the modified succinimide may be employed.
SUCCINATE ESTER
The modified succinimides are used in combination with a minor effective amount of a succinate ester of substantially saturated polymerized olefin-substituted succinic acid and aliphatic polyhydric alcohol. This dispersant combination provides an optimal balance of performance features (deposit control, fluoroelastomer seal compatibility, oxidation performance, low treating cost, etc.). The binary dispersant approach has allowed us to provide better performance than is attainable when only one of the dispersants is used alone.
Preferably, the polymerized olefin substituent of the substantially saturated polymerized olefin-substituted succinic acid is selected from the group consisting of polymerized propene and polymerized isobutene; and the aliphatic polyhydric alcohol is selected from the group consisting of glycerol, pentaerythritol, and sorbitol.
Such a succinate ester is disclosed by William M. Le Suer in U.S. Pat. No. 3,381,022, entitled "Polymerized Olefin Substituted Succinic Acid Esters," which is hereby incorporated by reference for all purposes.
Preferably, the polymerized olefin substituent of the substantially saturated polymerized olefin-substituted succinic acid is polymerized isobutene having a Mn of from 850 to 1200.
The succinate ester is added in an attempt to maintain and/or improve deposit control (in the Sequence VE and OM 364A) while providing exceptional fluoroelastomer seal compatibility performance (e.g. VW 3344). The succinimide, while providing enhanced deposit control, does adversely impact fluoroelastomers. This degradation in performance is attributed to the presence of basic nitrogen, which leads to dehydroflorination. The combination of the succinimide and the succinate ester allows the optimal balance of overall performance.
DETERGENTS
Preferably, the lubricating oil composition of the present invention contains minor effective amount of at least one detergent selected from the group consisting of metal sulfonates, metal alkyl phenates, metal salicylates, and mixtures thereof.
One detergent is a low overbased Group II metal sulfonate. It is thought that this detergent is instrumental in producing the better deposit control.
A second detergent is a highly basic Group II sulfonate detergent. It has some useful properties that are well known and have been used for years. Magnesium is preferable because it gives higher TBN at a given sulfated ash.
These detergents may be either natural petroleum sulfonates, or synethically alkylated aromatic sulfonates. These are well known in the art.
A third detergent is a sulfurized, highly basic alkyl phenate, such as disclosed by Walter W. Hanneman in U.S. Pat. No. 3, 178,368, entitled "Process For Basic Sulfurized Metal Phenates," which is hereby incorporated by reference for all purposes. It is thought that this detergent is instrumental in producing the better oxidation stability.
ZINC DITHIOPHOSPHATE
The general methods for preparing the dithiophosphoric acid esters and their corresponding metal salts are described in U.S. Pat. No. 3,089,850, 3,102,096, 3,293,181 and 3,489,682, which are all incorporated by reference for all purposes. Preferably, 100% of the zinc dithiophospate is derived from secondary alcohols. It is thought that the zinc dithiophospate is instrumental in producing the better oxidation stability and improved anti-wear properties.
Examples of metal compounds that may be reacted with the dithiophosphoric acid to produce zinc dithiophosphate include zinc oxide, zinc hydroxide, zinc carbonate, zinc propylate.
The total amount of the zinc dithiophosphate present is in the range of 3 to 30, preferably 10 to 20, millimoles of zinc per kilogram of finished product. The reason for this range is that less than 10 mm/kg could easily result in failing valve train wear performance, while greater than 20 mm/kg leads to the concern of phosphorus poisoning of the catalytic converters, so low phosphorus oils are desired.
OTHER ADDITIVES
Other additives which may be present in the lubricating oil composition include oxidation inhibitors, extreme pressure anti-wear inhibitors, foam inhibitors, friction modifiers, rust inhibitors, foam inhibitors, corrosion inhibitors, metal deactivators, pour point depressants, antioxidants, wear inhibitors, viscosity index improvers, and a variety of other well-known additives.
In one embodiment, the lubricating oil composition has from 1 to 8 wt % of polyamino alkenyl or alkyl succinimide; less than 6 wt % of succinate ester; from 1 to 15 millimoles of a low overbased metal sulfonate; from 10 to 25 millimoles of a highly overbased magnesium sulfonate; from 35 to 65 millimoles of a carbonated sulfurized metal alkylphenate; and from 10 to 20 millimoles of zinc dialkyldithiophosphate derived from secondary alcohols.
LUBRICATING OIL CONCENTRATES
The modified polyamino alkenyl or alkyl succinimides of this invention are compatible with fluoroelastomer seals. At concentration levels for which the additives of this invention are compatible with fluoroelastomer seals, they are effective as detergent and dispersant additives when employed in lubricating oils. When employed in this manner, the modified polyamino alkenyl or alkyl succinimide additive is usually present in from about 1 to about 5 percent by weight (on an oil-free basis) to the total composition and preferably less than about 3 percent by weight (on an oil-free basis).
As used herein, the phrase "dry polymer basis" indicates that only the modified succinimide compounds of this invention are considered when determining the amount of the additive relative to the remainder of a composition (e.g., lube oil composition, lube oil concentrate, fuel composition or fuel concentrate). Diluents and any other inactives are excluded.
It is also contemplated the modified succinimides of this invention may be employed as dispersants and detergents in hydraulic fluids, marine crankcase lubricants and the like. When so employed, the modified succinimide is added at from about 0.1 to 5 percent by weight (on a dry polymer basis) to the oil, and preferably at from 0.5 to 5 weight percent (on a dry polymer basis).
Lubricating oil concentrates are also included within the scope of this invention. The concentrates of this invention usually include from about 90 to 10 weight percent of an oil of lubricating viscosity and from about 10 to 90 weight percent (on an oil-free basis) of the compounds of this invention. Typically, the concentrates contain sufficient diluent to make them easy to handle during shipping and storage. Suitable diluents for the concentrates include any inert diluent, preferably an oil of lubricating viscosity, so that the concentrate may be readily mixed with lubricating oils to prepare lubricating oil compositions. Suitable lubricating oils which can be used as diluents typically have viscosities in the range from about 35 to about 500 Saybolt Universal Seconds (SUS) at 100 .degree. F. (38.degree. C.), although an oil of lubricating viscosity may be used.
The following examples are offered to specifically illustrate this invention. These examples and illustrations are not to be construed in any way as limiting the scope of this invention.
EXAMPLES
Example 1
(Preparation of PIBSA 2200 (succinic ratio=1.1)
A 35.186 Kg, 16 mol., sample of Parapol 2200 (a 2200 Mn polybutene available from Exxon Chemical Company) was charged to a reactor and heated to 232.degree. C. During this time, the reactor was pressurized to 40 psig with nitrogen and then vented three times to remove oxygen. The reactor was pressurized to 24.7 psia. Then 1500 g maleic anhydride was added over a thirty-minute period. Then 4581 g maleic anhydride was added over a 4-hour period. The total charge mole ratio (CMR) of maleic anhydride to polybutene was 3.88. After the maleic anhydride addition was completed, the reaction was held at 232.degree. C. for 1.5 hour. Then the reaction was cooled and the pressure reduced to 0.4 psia to remove any unreacted maleic anhydride. To this was then added a light neutral diluent oil. This was heated to 160.degree. C. for 24 hours and was then filtered. This product was found to contain 37.68 wt. % actives and had a saponification number of 19.7 mg KOH/g sample. The succinic ratio was 1.1 based on a polybutene molecular weight of 2246 determined by GPC.
Example 2
Preparation of PIBSA 1300 (succinic ratio=1.1)
The procedure of Example 1 was repeated except that Parapol 1300 (a 1300 Mn polybutene available from Exxon Chemical Company) was used instead of Parapol 2200. After dilution with diluent oil and filtration, this product was found to contain 49.6 wt. % actives and a saponification number of 42.2 mg KOH/g sample. The succinic ratio was 1.1 based on a polybutene molecular weight of 1300.
Example 3
Preparation of PIBSA 2200 (succinic ratio=1.5)
Parapol 2200, 42.8 Kg, 19.45 mol, was charged to a reactor and the temperature was increased to 150.degree. C. During this time, the reactor was pressurized to 40 psig with nitrogen and then vented three times to remove oxygen. Then at 150.degree. C., maleic anhydride, 429 g, 43.82 mol, and di-t-butylperoxide, 523 g, 3.58 mol, was added. The first 25% was added over 30 minutes. The remainder was then added over 11.5 hours. The CMR of maleic anhydride to polybutene was 2.25. The reaction was held at 150.degree. C. for one hour. Then the reactor was heated to 190.degree. C. for 1 hour to destroy any remaining di-t-butylperoxide. Then vacuum was applied to the reactor and the unreacted maleic anhydride was removed. This material was then diluted with a light neutral oil and filtered. The product after filtration had a saponification number of 31.6 mg KOH/g sample and contained 45.62 wt. % actives. The succinic ratio was 1.5 for this material based on a polybutene molecular weight of 2200.
Example 4A
Preparation of PIBSA 1300 (succinic ratio=1.9)
Parapol 1300, 6.9 Kg, 47.6 mol, was charged to a reactor and the temperature was increased to 150.degree. C. During this time, the reactor was pressurized to 40 psig with nitrogen and then vented three times to remove oxygen. Then at 150.degree. C., maleic anhydride, 9332.66 g (95.23 mol), and di-t-butylperoxide, 1280 g (8.77 mol) was added over 5 hours. Then the reaction was maintained at 150.degree. C. for an additional 2 hours. The reaction was then heated to 190.degree. C. for 1 hour to destroy any residual peroxide. The pressure was then reduced to 0.4 psia and the excess maleic anhydride was removed. The product was found to contain 65.4 wt. % actives and had a saponification number of 94.5 mg KOH/g sample. The succinic ratio was 1.9 for this material based on a polybutene molecular weight of 1300.
Example 4B
Preparation of PIBSA 1300 (succinic ratio =1.5)
In order to produce a PIBSA with a succinic ratio of 1.5, the product from Example 4A, 629.1 g (succinic ratio 1.9), was blended with diluent oil, 786.1 g. and the PIBSA 1300 (succinic ratio=1.1) from Example 2,962.8 g (succinic ratio 1.1 ). This gave 2388 g of PIBSA 1300 (succinic ratio=1.5) with a saponification number of 40.1 and wt. % actives of 35.4 and a succinic ratio of 1.5.
Example 5
Preparation of BIS HPA-X PIBSA 2200 Succinimide (succinic ratio=1.1)
To a 22 L three-necked flask equipped with a Dean Stark trap was added 7655 g (1.34 mol) of PIBSA from Example 1. This was heated to 130.degree. C. under nitrogen with stirring and to this was added HPA-X, 162.2 g (0.59 mol) over 2 hours. The temperature was increased to 165.degree. C. The amine/PIBSA CMR was 0.44. The reaction was heated an additional 4 hours at 165.degree. C. A total of 25 cc water was removed. This product was analyzed and found to contain 0.74%N, 17.0 TBN, 1.08 TAN, a viscosity at 100.degree. C. of 427.6 cSt and a specific gravity at 15.degree. C. of 0.9106. This product contained about 40% active material.
Examples 6-10, 13 and 14
Preparation of Other Succinimides
A number of other succinimides were prepared from a variety of PIBSA's and amines using the procedure reported in Example 5. TETA is triethylene tetramine. The analytical data for these products are reported in Table I.
Example 11
Preparation of Ethylene Carbonate-Treated BIS HPA-X PIBSA 1300 (succinic ratio=1.1)
The product from Example 8, BIS HPA-X PIBSA 1300 (succinic ratio =1.1), 146.2 Kg, was charged to a reactor and the temperature was heated to 100.degree. C. To this was added 20.4 Kg of ethylene carbonate over thirty minutes. The temperature was increased to 165.degree. C. over 2.5 hours and then maintained at this temperature for 2 hours. A total of 14 Kg of product was obtained. This product was analyzed and found to contain 1.51% N, 20.3 TBN, a viscosity at 100.degree. C. of 446.6 cSt, and a specific gravity at 15.degree. C. of 0.9393. The analytical data for this material is contained in Table I.
Examples 12, 13 and 15-19.
Preparation of Other Ethylene Carbonate-Treated Succinimides
A number of other post-treated succinimides were prepared from a variety of succinimides prepared from a variety of PIBSA's and amines using the procedures reported in the previous examples. These materials are reported in Table I.
Example 20
Preparation of a Bis HPA-X Succinimide from PIBSA 1300 (succinic ratio=1.9)
PIBSA 1300 prepared as in Example 4A (succinic ratio=1.9), 13051 g, was mixed with 10281 g diluent oil. This was heated to 75.degree. C. and to this was added with stirring 1512 g HPA-X, 5.5 mol. The amine/PIBSA CMR was 0.5 and the wt. % actives were calculated to be about 40%. The temperature was heated to 169.degree. C. over two hours and kept there for an additional two hours. Vacuum was applied to help remove the water. Upon cooling, a gel formed. So the reaction was reheated to 165.degree. C. under full vacuum for one additional hour. The product had 1.94 %N, TBN=34.2, viscosity at 100.degree. C. of 1267 cSt, and specific gravity at 15.degree. C. of 0.9320. Then 2638 g of this product was charged to a reactor and heated to 165.degree. C. To this was added 459.6 g ethylene carbonate (5.2 mol). The ethylene carbonate to basic nitrogen ratio was 2.0. When about half of the ethylene carbonate was added, massive amounts of a gel were formed. This could not be redissolved by prolonged heating or by the addition of 500 g diluent oil. The reaction was stopped. This reaction indicates that there is a gel problem when using PIBSA 1300 with a succinic ratio of 1.9.
Blending of Samples on an Equal Basis
We chose to blend and test the additives in Examples 5-19 on an equal wt. % actives basis. This was because we were trying to compare products from four different PIBSA's with different molecular weights and different succinic ratios, and two different amines with and without ethylene carbonate treatment. In order to do this, we calculated the %N and TBN that was expected for these compounds from the molecular formulas for a product that contained 40 wt. % actives. These data are reported in Table II. The succinimides from Examples 5-18 were then blended into the finished oil for testing at a concentration of 7.5% of the 40 wt. % actives material or at 3% on a dry polymer basis. The amounts of succinimides were adjusted to take into account the differences between the %N of the particular batch and the %N expected for the example. For Example 19, a 5% blend of 50 wt. % actives material or 3% on a dry polymer basis was made.
The additive compounds prepared in accordance with preceding Examples 5-19 were tested for fluoroelastomer seal compatibility using the Volkswagen PV-3344 test procedure for seal testing of motor oils. The results are displayed in Table III. The PV-3344 test procedure is a revised version of the earlier PV-3334 test procedure. This test procedure measures the change in physical properties of elastomer seals after they have been suspended in an oil solution. Tensile strength at break (TSB) and elongation at break (ELB) of the elastomer seals are measured. In addition, the seals are also visually inspected for cracks (CR) after they are removed from the test oil. Details of the PV-3344 test procedure are available from Volkswagen.
The detergency properties of the additive compounds were then tested using the Sequence VE engine test procedure, as defined in ASTM Proposed Method:212. This test measures, among other things, average engine sludge (AES) and average engine varnish (AEV). The AES and AEV results for the compounds of Examples 5-19 are shown in Table IV. A dosage or treat rate level of 3.0% (on a dry polymer basis) was chosen as an appropriate concentration level for the Seq. VE test since treat rate levels exceeding 3% are generally too high for the resulting additive package to be priced competitively in the marketplace. Examples 17 and 18 were each run at concentration levels of 2.0 and 1.5% (on a dry polymer basis).
Tables V-VII examine the effect of three structural parameters on PV-3344 and Seq. VE test performance. TSB data (@ a concentration level of 1.6 wt. %) is used as an indication of PV-3344 test performance. AES and AEV data are used as an indication of Seq. VE test performance. Table V shows the effect of the polybutene substituent's molecular weight on the additive's performance in both tests; Table VI shows the effect of the number of amine nitrogen atoms per mole on the additive's performance in both tests; and Table VII shows the effect of post-treatment with ethylene carbonate on the additive's performance in both tests. In Tables V-VII, the compounds are listed in pairs. For each pair, the compounds differ only by the feature examined in the respective table. For instance, the first pair of compounds listed in Table V (effect of polybutene Mn) compares Examples 6 and 10. Example 6 has a succinic ratio of 1.1, is made from a TETA polyamine, is not post-treated with ethylene carbonate, and contains a 1300 Mn polybutene substituent. Example 10 likewise has a succinic ratio of 1.1, is made from a TETA polyamine, and is not post-treated with ethylene carbonate. However, Example 10 contains a 2200 Mn polyisobutene substituent.
Table V demonstrates that a polyisobutene Mn of 2200 gives better PV-3344 and better Seq. VE results than a polyisobutene Mn of 1300.
When comparing TETA (4N atoms per mole) and HPA-X (avg. of 6.5 N atoms per mole) polyamines, Table VI shows better PV-3344 performance for TETA. The Seq. VE (AES) results for HPA-X were slightly better than for TETA. Also, Seq. VE (AEV) results were significantly better for the HPA-X polyamine than for TETA. While TETA appears to be the best amine type for PV-3344 performance, it is unacceptable for Seq. VE performance. The concentration levels of additives containing a TETA amine necessary to achieve suitable Seq. VE performance (AEV in particular) are generally unacceptable because they are too high to allow for a competitive treat rate.
The comparison of HPA-X and an admixture of DETA/HPA-X in Table VI shows that the DETA/HPA-X polyamine gave significantly better PV-3344 results. This comparison also shows that HPA-X was slightly better than the DETA/HPA-X admixture for Seq. VE (AES) results. Also, the Seq. VE (AEV) results were better for HPA-X than for the DETA/HPA-X admixture.
Table VII shows that post-treatment with ethylene carbonate gives slightly poorer PV-3344 performance than without post-treatment. However, those succinimides which were modified by post-treatment with ethylene carbonate performed significantly better in the Seq. VE test (both AES and AEV).
The conclusions that can be drawn from the above Tables are summarized in Table VIII.
Table VIII shows that the most desirable additives contain a 2200 Mn substituent, are derived from a polyamine having greater than 4 nitrogen atoms per mole, and are post-treated with ethylene carbonate.
While TETA appears to be the best amine type for PV-3344 performance, the concentration levels required for this amine type to achieve suitable Seq. VE performance (AEV results in particular) are unacceptable because they are too high to allow for a competitive treat rate. Accordingly, the amine should have greater than 4 nitrogen atoms per mole.
For multi-grade oil applications, the succinimide additive may be derived from a succinic anhydride having a succinic ratio of approximately 1.5. However, the viscosity index improvement which accompanies succinimides having succinic ratios of about 1.3 or greater is not always desirable. Instead, for some applications, such as single-grade oil formulation, a succinic ratio less than about 1.3, preferably closer to 1, is more desirable. Furthermore, Example 20 (made from the PIBSA of Example 4A) shows that succinic ratios of about 1.9 are unacceptable because gels are formed. Accordingly, succinic ratios greater than 1 but less than about 2 are acceptable, with succinic ratios less than about 1.7 preferred.
Succinimide additives having a 2200 Mn alkenyl or alkyl group which are derived from an amine having greater than 4 nitrogen atoms per mole, and which are post-treated with ethylene carbonate, are compatible with fluoroelastomer seals at concentration levels for which they are excellent detergent additives. Such additive compounds (Examples 17 and 18) pass the Seq. VE test at low concentration levels and are desirable because less of the additive is needed in additive packages, thereby resulting in lower-cost oil formulations.
Support for Formulation Selection
The formulation that serves as the basis for our unique technology is compounded from a combination of dispersants, detergents, ZnDTP and inhibitors. The dispersant balance of the formulation was critical in obtaining the required fluoroelastomer seal compatibility while simultaneously controlling engine deposits. Our detergents, ZnDTP and supplemental inhibitors were used to provide the remaining performance to yield a balanced formulation characteristic of today's automotive engine oils.
Example F-1
Fluoroelastomer Seal Compatibility
An experiment using four dispersants was conducted in the VW 3344 test. The VW 3344 test results and a description of the dispersants is contained below. The experiments were conducted in finished oils that contained 6% total dispersant, a detergent system of HOB Ca sulfonate and carbonated Ca phenate, ZnDTP (mixture of secondary and primary) and a supplemental antioxidant blended as a 15W-40 using mineral base oils and a nondispersant VI improver.
The targeted performance for this test series was: TSB.gtoreq.8, ELB.gtoreq.160 and no visible cracks. From data contained in table F1-2, the performance benefits of the new dispersants series (D-3 and D-4) in combination with D-1 are evident.
Example F2
Detergent Selection Using Novel Dispersants Engine Rust Performance
The detergent selection has a substantial impact on the engine rust performance as measured in the Sequence IID (ASTM STP 315H Part 1). The following table provides data on the rust performance a formulations that incorporate the modified succinimides and various detergents. All tests used (D-3) succinimide +(D-1) succinate ester dispersants and 100% secondary type ZnDTP in combination with the detergents listed, and without supplemental ashless rust inhibitors. The finished oils was a 15W-40 formulated from mineral base oils and a nondispersant VI improver.
From Table F2-1, it can be seen that the Sequence IID rust performance varies from 7.03 to 8.9. For the average engine performance varies from 7.03 to 8.9. For the average engine rust (AER) rating, the results are on a 0 to 10 scale. The rating of 10 is a part free of deposits or discoloration. The data demonstrate that the formulation with a combination of Ca phenate and Mg sulfonate has an AER performance advantage over those using only Ca phenate or Ca phenate/sulfonate technology.
Example F3
Dispersant Selection Using Novel Dispersants Engine Deposit Performance
The engine deposit formation in the Sequence VE gasoline engine demonstrate an advantage of the our novel new dispersants over other variants specifically for engine deposits.
From the results listed in table F3-1, it can be seen that the targeted performance (AES in the range of 9.0 and AEV in the range of 5.0) for the Sequence VE deposits are attainable.
Further testing was conducted in the 0M 364A diesel engine test (a widely accepted deposit test describe in CEC documentation). The following table offers a direct comparison of the new technology to that of older dispersants. The finished oils were formulated as SAE 15W-40 from mineral base oils and nondispersant or dispersant mixed polymer VI improvers.
From table F3-2, it can be seen that the formulation of an oil to meet the targeted performance of bore polish (BoPo)<16 and piston merits>24 is attainable using the new dispersant technology, while previous technology remained marginal in piston deposit control (even when with the help of a dispersant mixed polymer).
While the present invention has been described with reference to specific embodiments, this application is intended to cover those various changes and substitutions that may be made by those skilled in the art without departing from the spirit and scope of the appended claims.
Claims
What is claimed is:
1. A lubricating oil composition that is essentially free of chlorine, said lubricating oil composition comprising: (a) a major proportion of an oil of lubricating viscosity; and (b) a minor amount of a polyamino alkenyl or alkyl succinimide sufficient to be compatible with fluoroelastomer seals and simultaneously control engine deposits, wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of from 2000 to 2700 and a Mw/Mn ratio of from 1 to 5; and (ii) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the reaction product is post-treated with a cyclic carbonate; and wherein the level of chlorine in the composition is less than 50 ppm.
2. A lubricating oil composition according to claim 1 wherein the charge mole ratio of polyamine to succinic anhydride is from 0.35:1 to 0.6:1; and the charge mole ratio of cyclic carbonate to basic amine nitrogen in the reaction product is from 1.5:1 to 4:1.
3. A lubricating oil composition according to claim 1 wherein the polyolefin has a Mn of from 2100 to 2400.
4. A lubricating oil composition according to claim 3 wherein the polyolefin has a Mn of about 2200.
5. A lubricating oil composition according to claim 1 wherein the polyolefin is polybutene.
6. A lubricating oil composition according to claim 5 wherein the polybutene is polyisobutene.
7. A lubricating oil composition according to claim 1 wherein the polyalkylene polyamine has an average nitrogen atom to molecule ratio of less than 12.
8. A lubricating oil composition according to claim 7 wherein the polyalkylene polyamine has an average nitrogen atom to molecule ratio of from 5 to 7.
9. A lubricating oil composition according to claim 8 wherein the polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
10. A lubricating oil composition according to claim 8 wherein the polyalkylene polyamine comprises a mixture of: (a) diethylene triamine and (b) a polyamine that has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
11. A lubricating oil composition according to claim 1 wherein the succinic anhydride has a succinic ratio from 1 to less than 2.
12. A lubricating oil composition according to claim 11 wherein the succinic anhydride has a succinic ratio from 1 to less than 1.3.
13. A lubricating oil composition according to claim 11 wherein the succinic anhydride has a succinic ratio from 1.3 to 1.7.
14. A lubricating oil composition according to claim 1 wherein the cyclic carbonate is ethylene carbonate.
15. A lubricating oil composition according to claim 1 wherein the amount of the succinimide is from 1 to 5 weight percent on a dry polymer basis.
16. A lubricating oil composition according to claim 15 wherein the amount of the succinimide is less than 3 weight percent on a dry polymer basis.
17. A lubricating oil composition that is essentially free of chlorine, said lubricating oil composition comprising: (a) a major proportion of an oil of lubricating viscosity; and (b) a minor amount of a polyamino alkenyl or alkyl succinimide sufficient to be compatible with fluoroelastomer seals and simultaneously control engine deposits, wherein the amount of the succinimide is less than about 3 weight percent on a dry polymer basis, and wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyisobutene having a Mn of about 2200 and a Mw/Mn ratio of from 1 to 5, wherein the anhydride has a succinic ratio from 1 to 1.7; and (ii) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the charge mole ratio of polyamine to succinic anhydride is from 0.4:1 to 0.5:1; wherein the reaction product is post-treated with ethylene carbonate at a charge mole ratio of ethylene carbonate to basic amine nitrogen in the succinimide reaction product of from 2:1 to 3:1; and wherein the level of chlorine in the composition is less than 50 ppm.
18. A lubricating oil composition according to claim 17 wherein the polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
19. A lubricating oil composition according to claim 17 wherein the polyalkylene polyamine comprises a mixture of: (a) diethylene triamine and (b) a polyamine that has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
20. A lubricating oil concentrate that is essentially free of chlorine, said lubricating oil concentrate comprising (a) from about 90 to about 10 weight percent of an oil of lubricating viscosity; and (b) from about 10 to about 90 weight percent on an oil-free basis of a polyamino alkenyl or alkyl succinimide, wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of from 2000 to 2700 and a Mw/Mn ratio from 1 to 5; and (ii) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the reaction product is post-treated with a cyclic carbonate; and wherein the level of chlorine in the concentrate is less than 50 ppm.
21. A lubricating oil concentrate according to claim 20 wherein the succinic anhydride is derived from a polyisobutene having a Mn of about 2200 and a Mw/Mn ratio of from 1 to 5, and wherein the anhydride has a succinic ratio from 1 to 1.7.
22. A lubricating oil concentrate according to claim 20 wherein the charge mole ratio of polyamine to succinic anhydride is from 0.4:1 to 0.5:1; wherein the cyclic carbonate is ethylene carbonate; and wherein the charge mole ratio of ethylene carbonate to basic amine nitrogen in the succinimide reaction product is from 2:1 to 3:1.
23. A lubricating composition that is essentially free of chlorine, said lubricating oil composition comprising: (a) a major proportion of an oil of lubricating viscosity; (b) a minor amount of a polyamino alkenyl or alkyl succinimide sufficient to be compatible with fluoroelastomer seals and simultaneously control engine deposits, wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of from 2000 to 2700 and a Mw/Mn ratio of from 1 to 5; and (ii) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the reaction product is post-treated with a cyclic carbonate; and (c) a minor amount of a succinate ester of substantially saturated polymerized olefin-substituted succinic acid and aliphatic polyhydric alcohol; and wherein the level of chlorine in the composition is less than 50 ppm.
24. A lubricating oil composition according to claim 23 wherein the charge mole ratio of polyamine to succinic anhydride is from 0.35:1 to 0.6:1; and the charge mole ratio of cyclic carbonate to basic amine nitrogen in the reaction product is from 1.5:1 to 4:1.
25. A lubricating oil composition according to claim 23 wherein the polyolefin has a Mn of from 2100 to 2400.
26. A lubricating oil composition according to claim 25 wherein the polyolefin has a Mn of about 2200.
27. A lubricating oil composition according to claim 23 wherein the polyolefin is polybutene.
28. A lubricating oil composition according to claim 27 wherein the polybutene is polyisobutene.
29. A lubricating oil composition according to claim 23 wherein the polyalkylene polyamine has an average nitrogen atom to molecule ratio of less than 12.
30. A lubricating oil composition according to claim 29 wherein the polyalkylene polyamine has an average nitrogen atom to molecule ratio of from 5 to 7.
31. A lubricating oil composition according to claim 30 wherein the polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
32. A lubricating oil composition according to claim 30 wherein the polyalkylene polyamine comprises a mixture of: (a) diethylene triamine and (b) a polyamine that has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
33. A lubricating oil composition according to claim 23 wherein the succinic anhydride has a succinic ratio from 1 to less than 2.
34. A lubricating oil composition according to claim 33 wherein the succinic anhydride has a succinic ratio from 1 to less than 1.3.
35. A lubricating oil composition according to claim 33 wherein the succinic anhydride has a succinic ratio from 1.3 to 1.7.
36. A lubricating oil composition according to claim 23 wherein the cyclic carbonate is ethylene carbonate.
37. A lubricating oil composition according to claim 23 wherein the amount of the succinimide is from 1 to 5 weight percent on an oil-free basis.
38. A lubricating oil composition according to claim 37 wherein the amount of the succinimide is less than 3 weight percent on an oil-free basis.
39. A lubricating oil composition according to claim 23 wherein the polymerized olefin substituent of the substantially saturated polymerized olefin-substituted succinic acid is selected from the group consisting of polymerized propene and polymerized isobutene.
40. A lubricating oil composition according to claim 39 wherein the polymerized olefin substituent of the substantially saturated polymerized olefin-substituted succinic acid is polymerized isobutene having a Mn of from 850 to 1200.
41. A lubricating oil composition according to claim 23 wherein the aliphatic polyhydric alcohol is selected from the group consisting of glycerol, pentaerythritol, and sorbitol.
42. A lubricating oil composition that is essentially free of chlorine, said lubricating composition comprising: (a) a major proportion of an oil of lubricating viscosity; (b) a minor amount of a polyamino alkenyl or alkyl succinimide sufficient to be compatible with fluoroelastomer seals and simultaneously control engine deposits, wherein the amount of the succinimide is less than about 3 weight percent on an oil-free basis, and wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyisobutene having a Mn of about 2200 and a Mw/Mn ratio of from 1 to 5, wherein the anhydride has a succinic ratio from 1 to 1.7; and (ii) a polyalkylene polyamine having an average nitrogen atom to 1 molecule ratio of greater than 4.0; wherein the charge mole ratio of polyamine to succinic anhydride is from 0.4:1 to 0.5:1; wherein the reaction product is post-treated with ethylene carbonate at a charge mole ratio of ethylene carbonate to basic amine nitrogen in the succinimide reaction product of from 2:1 to 3:1; and (c) a minor amount of a succinate ester of polyisobutene-substituted succinic acid and aliphatic alcohol selected from the group consisting of glycerol, pentaerythritol, and sorbitol; wherein the polymerized isobutene has a Mn of from 850 to 1200; and wherein the level of chlorine in the composition is less than 50 ppm.
43. A lubricating oil composition according to claim 42 wherein the polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
44. A lubricating oil composition according to claim 42 wherein the polyalkylene polyamine comprises a mixture of: (a) diethylene triamine and (b) a polyamine that has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
45. A lubricating oil concentrate that is essentially free of chlorine, said lubricating oil concentrate comprising (a) from about 90 to about 10 weight percent of an oil of lubricating viscosity; and (b) from about 10 to about 90 weight percent on an oil-free basis of an additive mixture comprising: (i) a polyamino alkenyl or alkyl succinimide, wherein the succinimide comprises the reaction product of: (1) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of from 2000 to 2700 and a Mw/Mn ratio from 1 to 5; and (2) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the reaction product is post-treated with a cyclic carbonate; and (ii) a succinate ester of polyisobutene-substituted succinic acid and aliphatic alcohol selected from the group consisting of glycerol, pentaerythritol, and sorbitol; and wherein the level of chlorine in the concentrate is less than 50 ppm.
46. A lubricating oil concentrate according to claim 45 wherein the succinic anhydride is derived from a polyisobutene having a Mn of about 2200 and a Mw/Mn ratio of from 1 to 5, and wherein the anhydride has a succinic ratio from 1 to 1.7.
47. A lubricating oil concentrate according to claim 45 wherein the charge mole ratio of polyamine to succinic anhydride is from 0.4:1 to 0.5:1; wherein the cyclic carbonate is ethylene carbonate; and wherein the charge mole ratio of ethylene carbonate to basic amine nitrogen in the succinimide reaction product is from 2:1 to 3:1.
48. A lubricating composition that is essentially free of chlorine, said lubricating oil composition comprising: (a) a major proportion of an oil of lubricating viscosity; (b) a minor amount of a polyamino alkenyl or alkyl succinimide in the range of from 1 to 8 wt % sufficient to be compatible with fluoroelastomer seals and simultaneously control engine deposits, wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of from 2700 to 2700 and a Mw/Mn ratio of from 1 to 5; and (ii) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the reaction product is post-treated with a cyclic carbonate; (c) a minor amount less than 6 wt % of a succinate ester of substantially saturated polymerized olefin-substituted succinic acid and aliphatic polyhydric alcohols; (d) a minor amount of at least one detergent selected from the group consisting of metal sulfonates, metal alkyl phenates, metal salciylates, and mixtures thereof; and (e) a minor amount of zinc dialkyldithiophosphate; and wherein the level of chlorine in the composition is less than 50 ppm.
49. A lubricating oil composition according to claim 48 wherein the charge mole ratio of polyamine to succinic anhydride is from 0.35:1 to 0.6:1; and the charge mole ratio of cyclic carbonate to basic amine nitrogen in the reaction product is from 1.5:1 to 4:1.
50. A lubricating oil composition according to claim 48 wherein the polyolefin has a Mn of from 2100 to 2400.
51. A lubricating oil composition according to claim 50 wherein the polyolefin has a Mn of about 2200.
52. A lubricating oil composition according to claim 48 wherein the polyolefin is polybutene.
53. A lubricating oil composition according to claim 52 wherein the polybutene is polyisobutene.
54. A lubricating oil composition according to claim 48 wherein the polyalkylene polyamine has an average nitrogen atom to molecule ratio of less than 12.
55. A lubricating oil composition according to claim 54 wherein the polyalkylene polyamine has an average nitrogen atom to molecule ratio of from 5 to 7.
56. A lubricating oil composition according to claim 55 wherein the polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
57. A lubricating oil composition according to claim 55 wherein the polyalkylene polyamine comprises a mixture of: (a) diethylene triamine and (b) a polyamine that has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
58. A lubricating oil composition according to claim 48 wherein the succinic anhydride has a succinic ratio from about 1 to less than about 2.
59. A lubricating oil composition according to claim 58 wherein the succinic anhydride has a succinic ratio from about 1 to less than about 1.3.
60. A lubricating oil composition according to claim 58 wherein the succinic anhydride has a succinic ratio from about 1.3 to about 1.7.
61. A lubricating oil composition according to claim 48 wherein the cyclic carbonate is ethylene carbonate.
62. A lubricating oil composition according to claim 48 wherein the amount of the succinimide is from 1 to 5 weight percent on an oil-free basis.
63. A lubricating oil composition according to claim 62 wherein the amount of the succinimide is less than 3 weight percent on an oil-free basis.
64. A lubricating oil composition according to claim 48 wherein the polymerized olefin substituent of the substantially saturated polymerized olefin-substituted succinic acid is selected from the group consisting of polymerized propene and polymerized isobutene.
65. A lubricating oil composition according to claim 48 wherein the polymerized olefin substituent of the substantially saturated polymerized olefin-substituted succinic acid is polymerized isobutene having a Mn of from 850 to 1200.
66. A lubricating oil composition according to claim 48 wherein the aliphatic polyhydric alcohol is selected from the group consisting of glycerol, pentaerythritol, and sorbitol.
67. A lubricating oil composition according to claim 48 wherein the at least one detergent comprises: (a) a low overbased Group II metal sulfonate; (b) a highly overbased magnesium sulfonate; and (c) a carbonated sulfurized metal alkylphenate.
68. A lubricating oil composition according to claim 48 wherein the zinc dialkyldithiophosphate is derived from secondary alcohols.
69. A lubricating oil composition that is essentially free of chlorine, said lubricating composition comprising: (a) a major proportion of an oil of lubricating viscosity; (b) a minor amount of a polyamino alkenyl or alkyl succinimide in the range of from 1 to 8 wt % sufficient to be compatible with fluoroelastomer seals and simultaneously control engine deposits, wherein the amount of the succinimide is less than about 3 weight percent on an oil-free basis, and wherein the succinimide comprises the reaction product of: (i) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyisobutene having a Mn of about 2200 and a Mw/Mn ratio of from 1 to 5, wherein the anhydride has a succinic ratio from 1 to 1.7; and (ii) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the charge mole ratio of polyamine to succinic anhydride is from 0.4:1 to 0.5:1; wherein the reaction product is post-treated with ethylene carbonate at a charge mole ratio of ethylene carbonate to basic amine nitrogen in the succinimide reaction product of from 2:1 to 3:1; (c) a minor amount less than 6 wt % of a succinate ester of polyisobutene-substituted succinic acid and aliphatic alcohol selected from the group consisting of glycerol, pentaerythritol, and sorbitol; (d) from 1 to 15 millimoles of a low overbased metal sulfonate; (e) from 10 to 25 millimoles of a highly overbased magnesium sulfonate; (f) from 35 to 65 millimoles of a carbonated sulfurized metal alkylphenate; and (g) from 10 to 20 millimoles of zinc dialkyldithiophosphate derived from secondary alcohols; and wherein the level of chlorine in the composition is less than 50 ppm.
70. A lubricating oil composition according to claim 69 wherein the polyalkylene polyamine has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
71. A lubricating oil composition according to claim 69 wherein the polyalkylene polyamine comprises a mixture of: (a) diethylene triamine and (b) a polyamine that has a Mn of from 250 to 340, and has an average nitrogen atom to molecule ratio of about 6.5.
72. A lubricating oil concentrate that is essentially free of chlorine, said lubricating oil concentrate comprising (a) from about 90 to about 10 weight percent of an oil of lubricating viscosity; and (b) from about 10 to about 90 weight percent on an oil-free basis of a mixture of: (i) a polyamino alkenyl or alkyl succinimide, wherein the succinimide comprises reaction product of: (1) an alkenyl- or alkyl-substituted succinic anhydride derived from a polyolefin having a Mn of from 2700 to 2700 and a Mw/Mn ratio from 1 to 5; and (2) a polyalkylene polyamine having an average nitrogen atom to molecule ratio of greater than 4.0; wherein the reaction product is post-treated with a cyclic carbonate; (ii) a succinate ester of polyisobutene-substituted succinic acid and aliphatic alcohol selected from the group consisting of glycerol, pentaerythritol, and sorbitol, wherein the succinate ester is essentially free of chlorine; (iii) a minor amount of a low overbased metal sulfonate; (iv) a minor amount of a highly overbased magnesium sulfonate; (v) a minor amount of a carbonated sulfurized metal alkylphenate; and (vi) a minor amount of zinc dialkyldithiophosphate derived from secondary alcohols; and wherein the level of chlorine in the concentrate is less than 50 ppm.
73. A lubricating oil concentrate according to claim 72 wherein the succinic anhydride is derived from a polyisobutene having a Mn of about 2200 and a Mw/Mn ratio of from 1 to 5, and wherein the anhydride has a succinic ratio from 1 to 1.7.
74. A lubricating oil concentrate according to claim 72 wherein the charge mole ratio of polyamine to succinic anhydride is from 0.4:1 to 0.5:1; wherein the cyclic carbonate is ethylene carbonate; and wherein the charge mole ratio of ethylene carbonate to basic amine nitrogen in the succinimide reaction product is from 2:1 to 3:1.
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