EP0535191A1

EP0535191A1 - Overbased alkali metal salts and methods for making the same.

Info

Publication number: EP0535191A1
Application number: EP92907871A
Authority: EP
Inventors: John M Cahoon; Jack L Karn; Mary F Salomon; Craig D Tipton
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 1991-04-19
Filing date: 1992-02-27
Publication date: 1993-04-07
Anticipated expiration: 2012-02-27
Also published as: AU659450B2; NO924683D0; EP0535191B1; JP3157830B2; CA2085372A1; ES2094351T3; MX9201752A; NO924683L; FI925776A0; BR9205242A; DE69213376D1; DE69213376T2; JPH05508181A; WO1992018587A1; AU1533992A; ATE142249T1; FI925776A

Abstract

The invention relates to a composition, comprising: at least one basic alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl group is derived from a polyalkene having an M &cir& NOt n of at least 600, provided that when the organic compound is a sulfonic acid, the polyalkene has an M &cir& NOt n of at least 900; and provided that when the acidic organic compound is a mixture of acidic organic compounds containing a carboxylic acid and a sulfonic acid which has a hydrocarbyl group derived from a polyalkene having an M &cir& NOt n of less than 900, then the carboxylic acid comprises at least 10 % of the equivalents of the mixture.

Description

Title: OVERBASED ALKALI METAL SALTS AND METHODS FOR MAKING THE SAME

FIELD OF THE INVENTION This invention relates to novel overbased alkali metal salts of sulfonic acids, carboxylic acids, phenols or mixtures thereof. INTRODUCTION TO THE INVENTION

Alkali metal overbased metal salts of many organic acids are known compounds and are useful in numer¬ ous applications including lubricating compositions. The compounds are prepared by reacting an acidic material with a reaction mixture comprising basic metal compounds, an acidic organic compound or salt and a promoter. Generally, the acidic material is carbon dioxide and the promoters are usually lower alkyl alcohols, usually methanol, ethanol or butanol or lower alkyl acids. In the overbasing process, the promoter improves contact between the acidic material and the basic metal compound. The result is an oil-soluble or dispersible form of the basic metal-acidic material salt, usually a metal carbonate. Procedures for making these overbased compounds are generally known.

Canadian Patent 1,055,700 relates to basic alkali sulfonate dispersions and processes. U.S. Patent 4,326,972 relates to concentrates, lubricant compositions and methods for improving fuel economy of internal combustion engines. These compositions have as an essential ingredient a specific sulfurized composition and a basic alkali metal sulfonate. U.S. Patent 4,904,401 relates to lubricating oil compositions. These compositions may contain a basic alkali metal salt of at least one sulfonic or carboxylic acid. U.S. Patent 4,938,881 relates to lubricating oil compositions and concentrates. These compositions and concentrates include at least one basic alkali metal salt of sulfonic or carboxylic acid. U.S. Patent 4,952,328 relates to lubricating oil compositions. These composi¬ tions contain from about 0.01% to about 2% by weight of at least one basic alkali metal salt of sulfonic or carboxylic acid.

It has been discovered that overbased alkali metal salts of high molecular weight acidic organic com¬ pounds may be prepared. One of the problems associated with working with high molecular weight material is effec- tively providing contact between the acidic material over- basing and the alkali metal compounds. Generally, previ¬ ously used low molecular weight, i.e. highly volatile, materials are ineffective as promoters for high molecular weight acidic organic compounds in providing the contact necessary to produce useful overbased compounds. Further¬ more, the temperature used to overbase high molecular weight acidic organic compounds generally exceeds the boiling point of highly volatile promoters. The high molecular weight alkali metal salts are useful in many applications including lubricating applications. These compounds provide strongly basic components (alkali metal- acidic material, usually alkali metal carbonate) along with high molecular weight, solubilizing substitutents.

SUMMARY OF THE INVENTION The invention relates to a composition, compris¬ ing: at least one basic alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl group is derived from a polyalkene having an Mn of at least 600, provided that when the organic compound is a sulfonic acid, the polyalkene has an Mn of at least 900; and provided that when the acidic organic compound is a mixture of acidic organic compounds containing a carboxylic acid and a sulfonic acid which has a hydrocarbyl group derived from a polyalkene having an ϊϊn of less than 900, then the carboxylic acid comprises at least 10% of the equivalents of the mixture.

The invention also relates to a process for preparing basic alkali metal salts of acidic organic compounds comprising the steps of:

(A) adding at least one basic alkali metal compound to a reaction mixture comprising at least one alkali metal salt of a hydrocarbyl-substituted acidic organic composition and removing free water from the reaction mixture; and

(B) concurrently, thereafter

(1) adding at least one basic alkali metal compound to the reaction mixture,

(2) adding at least one inorganic or lower carboxylic acidic material to the reaction mixture, and

(3) removing water from the reaction mixture, wherein the reaction temperature is sufficient to form an oil-soluble overbased alkali metal salt.

The overbased compositions of the present inven- tion are useful in many applications including paints, inks, coating, ceramics processing and lubricating applica¬ tions. These lubricants include crankcase lubricating oils for spark-ignited and compression-ignited internal combus¬ tion engines, including automobile and truck engines, two- cycle engines, aviation piston engines, marine and railroad diesel engines, and the like. They can also be used in gas engines, stationary power engines and turbines and the like. Automatic transmission fluids, transaxle lubricants, gear lubricants, metal-working lubricants, hydraulic fluids and other lubricating oil and grease compositions can also benefit from the incorporation therein of the compositions of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The term "hydrocarbyl" includes hydrocarbon, as well as substantially hydrocarbon, groups. Substantially hydrocarbon describes groups which contain non-hydrocarbon substituents which do not alter the predominately hydrocar¬ bon nature of the group.

Examples of hydrocarbyl groups include the following:

(1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl) , alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, aromatic-, aliphatic- and alicyclic-substituted aromatic substituents and the like as well as cyclic substituents wherein the ring is completed through another portion of the molecule (that is, for example, any two indicated substituents may together form an alicyclic radical) ;

(2) substituted hydrocarbon substituents, that is, those substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon substituent; those skilled in the art will be aware of such groups (e.g., halo (especially chloro and fluoro) , hydroxy, alkoxy, mercapto, alkylmer- capto, nitro, nitroso, sulfoxy, etc.);

(3) hetero substituents, that is, substituents which will, while having a predominantly hydrocarbon character within the context of this invention, contain other than carbon present in a ring or chain otherwise composed of carbon atoms. Suitable heteroatoms will be apparent to those of ordinary skill in the art and include, for example, sulfur, oxygen, nitrogen and such substituents as, e.g., pyridyl, furyl, thienyl, i idazolyl, etc. In general, no more than about 2, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group. Typically, there will be no such non-hydrocarbon substituents in the hydro¬ carbyl group. Therefore, the hydrocarbyl group is purely hydrocarbon. The present lubricating compositions contain an alkali metal basic salt of a carboxylic acid, sulfonic acid, phosphorus acid or a phenol. These basic salts are often referred to as overbased salts. The overbased salts are single phase, homogeneous Newtonian systems character¬ ized by a metal content in excess of that which would be present according to the stoichiometry of the metal and the particular organic compound reacted with the metal. The amount of excess metal is commonly expressed in metal ratio. The term "metal ratio" is the ratio of the total equivalents of the metal to the equivalents of the acidic organic compound. A neutral metal salt has a metal ratio of one. A salt having 4.5 times as much metal as present in a normal salt will have metal excess of 3.5 equivalents, or a ratio of 4.5. In the present invention, these salts preferably have a metal ratio from about 1.5 to about 40, preferably about 3 to about 30, more preferably about 3 to about 25.

The overbased materials are prepared by reacting an acidic material, typically carbon dioxide, with a mixture comprising a carboxylic acid, a sulfonic acid, phosphorus acid or a phenol, a reaction medium comprising at least one inert, organic solvent for said organic material, a stoichiometric excess of the above-described metal compound, and a promoter. Preferably, the overbased materials are prepared with carboxylic acids or sulfonic acids. The carboxylic and sulfonic acids may have sub¬ stituent groups derived from the polyalkenes. The polyal¬ kene is characterized as containing from at least about 45, preferably at least about 50, more preferably about 60, up to about 300 carbon atoms, generally about 200, preferably about 100, more preferably about 80. In one embodiment, the polyalkene is characterized by an Mn (number average molecular weight) value of at least about 600. Generally, the polyalkene is characterized by an Mn value of about 600, preferably about 700, more preferably about 800, still more preferably about 900 up to about 5000, preferably 2500, more preferably 2000, still more preferably about 1500. In another embodiment Mn varies between about 600, preferably about 700, more preferably about 800 to about 1200 or 1300.

The abbreviation Mn is the conventional symbol representing number average molecular weight. Gel perme¬ ation chromatography (GPC) is a method which provides both weight average and number average molecular weights as well as the entire molecular weight distribution of the poly¬ mers. For purpose of this invention a series of fraction¬ ated polymers of isobutene, polyisobutene, is used as the calibration standard in the GPC. The techniques for determining Mn and Mw values of polymers are well known and are described in numerous books and articles. For example, methods for the determi¬ nation of Mn and molecular weight distribution of polymers is described in W. . Yan, J.J. Kirkland and D.D. Bly, "Modern Size Exclusion Liquid Chromatographs", J. Wiley & Sons, Inc., 1979.

The polyalkenes include homopolymers and inter- polymers of polymerizable olefin monomers of 2 to about 16 carbon atoms; usually 2 to about 6, preferably 2 to about 4, more preferably 4. The olefins may be monoolefins such as ethylene, propylene, 1-butene, isobutene, and 1-octene; or a polyolefinic monomer, preferably diolefinic monomer, such as 1,3-butadiene and isoprene. The polyalkenes are prepared by conventional procedures. Suitable carboxylic acids from which useful alkali metal salts can be prepared include aliphatic, cycloaliphatic and aromatic mono- and polybasic carboxylic acids free from acetylenic unsaturation, including naph- thenic acids, alkyl- or alkenyl-substituted cyclopentanoic acids, alkyl- or alkenyl-substituted succinic acids or anhydrides, alkyl- or alkenyl-substituted cyclohexanoic acids, and alkyl- or alkenyl-substituted aromatic carboxyl¬ ic acids. The acids are generally prepared by reacting an unsaturated acid or derivative thereof with one of the above-described polyalkenes or derivative thereof. Gener¬ ally, the unsaturated acid is an alpha, beta unsaturated carboxylic acid. Examples of these acids include maleic, itaconic, citraconic, glutaric, crotonic, acrylic, and methacrylic acids or derivatives thereof. The derivatives of the unsaturated carboxylic acid include acids, anhy¬ drides, metal or amine salts, lower alkyl esters (C_j_₇ alkyl esters) , and the like.

Illustrative carboxylic acids include propylenyl- substituted glutaric acid, polybutenyl-substituted succinic acids derived from a polybutene (Mn equals about 200-1,500, preferably about 300-1500) , propenyl-substituted succinic acids derived from polypropylenes (Mn equal 200-1000) , acids, acids formed by oxidation of petrolatum or of hydrocarbon waxes, available mixtures of two or more carboxylic acids and mixtures of these acids, their metal salts, and/or their anhydrides.

In one embodiment, the carboxylic acids are aromatic carboxylic acids. A group of useful aromatic carboxylic acids are those of the formula

wherein Rj is an aliphatic hydrocarbyl group preferably derived from the above-described polyalkenes, a is a number in the range of 1 to about 4, usually 1 or 2, Ar is an aromatic group, each X is independently sulfur or oxygen, preferably oxygen, b is a number in the range of from 1 to about 4, usually l or 2, c is a number in the range of zero to about 4, usually 1 to 2, with the proviso that the sum of a, b and c does not exceed the number of valences of Ar. Examples of aromatic carboxylic acids include substituted benzoic, phthalic and salicylic acids.

The R_x group is a hydrocarbyl group that is directly bonded to the aromatic group Ar. Examples of Rj groups include substituents derived from polymerized olefins such as polyethylenes , polypropylenes, polybutyl- enes, ethylene-propylene copolymers, chlorinated olefin polymers and oxidized ethylene-propylene copolymers.

The aromatic group Ar may have the same structure as any of the aromatic groups Ar discussed below. Examples of the aromatic groups that are useful herein include the polyvalent aromatic groups derived from benzene, naph¬ thalene, anthracene, etc., preferably benzene. Specific examples of Ar groups include phenylenes and naphthylene, e.g., methylphenylenes, ethoxyphenylenes, isopropylphenyl- enes, hydroxyphenylenes, dipropoxynaphthylenes, etc. Within this group of aromatic acids, a useful class of carboxylic acids are those of the formula

wherein Rj is defined above, a is a number in the range of from 1 to about 4, preferably 1 to about 3; b is a number in the range of 1 to about 4, preferably 1 to about 2, c is a number in the range of zero to about 4, preferably 1 to about 2, and more preferably l; with the proviso that the sum of a, b and c does not exceed 6. Preferably, b and c are each one and the carboxylic acid is a salicylic acid. Overbased salts prepared from salicylic acids wherein the aliphatic hydrocarbon substituents (R^ are derived from the above-described polyalkenes, particularly polymerized lower 1-mono-olefins such as polyethylene, polypropylene, polyisobutylene, ethylene/propylene copoly¬ mers and the like and having average carbon contents of about 50 to about 400 carbon atoms are particularly useful. The above aromatic carboxylic acids are well known or can be prepared according to procedures known in the art. Carboxylic acids of the type illustrated by these formulae and processes for preparing their neutral and basic metal salts are well known and disclosed, for exam¬ ple, in U.S. Patents 2,197,832; 2,197,835; 2,252,662; 2,252,664; 2,714,092; 3,410,798; and 3,595,791. These references are incorporated by reference for disclosure of carboxylic acid, their basic salt and processes of making the same.

The sulfonic acids useful in making the overbased salts (A) of the invention include the sulfonic and thio- sulfonic acids. Generally they are salts of sulfonic acids. The sulfonic acids include the mono- or polynuclear aromatic or cycloaliphatic compounds. The oil-soluble sulfonic acids can be represented for the most part by one of the following formulae: R^T-fSO^.H and R₃-(S0₃)_bH, wherein T is a cyclic nucleus such as, for example, ben¬ zene, naphthalene, anthracene, diphenylene oxide, diphenyl- ene sulfide, petroleum naphthenes, etc. Specific examples of R₂ and R₃ are groups derived from petrolatum, saturated and unsaturated paraffin wax, and the above-described polyalkenes. The groups T, R₂, and R₃ in the above Formulae can also contain other inorganic or organic substituents in addition to those enumerated above such as, for example, hydroxy, mercapto, halogen, nitro, amino, nitroso, sulfide, disulfide, etc. In the above Formulae, a and b are at least 1. Illustrative examples of these sulfonic acids include polybutene or polypropylene substituted naphthalene sulfonic acids, sulfonic acids derived by the treatment of polybutenes having a number average molecular weight (Mn) in the range of 700 to 5000, preferably 700 to 1200, more preferably about 1500 with chlorosulfonic acids, paraffin wax sulfonic acids, polyethylene (Mn equals about 900-2000, preferably about 900-1500, more preferably 900-1200 or 1300) sulfonic acids, etc. Preferred sulfonic acids are mono-, di-, and tri-alkylated benzene (including hydroge¬ nated forms thereof) sulfonic acids.

In another embodiment, the hydrocarbyl-substi- tuted acidic organic compound is a phenol. The phenol may be a coupled or uncoupled phenol, preferably a substituted phenol. The phenols may be alkylene coupled, wherein the alkylene group contains from 1 to about 8 carbon atoms, preferably 1 to about 4 carbon atoms, more preferably 1 carbon atom. Alkylene coupled phenols are prepared by procedures known to those in the art. Generally, the phenol is reacted with an aldehyde, usually formaldehyde or a formaldehyde precursor such as paraformaldehyde, at a temperature from about 50°C to about 175°C. A diluent may be used such as mineral oil, naphtha, kerosene, toluene or xylene. The phenol may be a sulfur-coupled phenol which is prepared by reacting a sulfurizing agent with the phenol. The sulfurizing agent generally is elemental sulfur or a sulfur halide, such as sulfur monochloride or sulfur dichloride, preferably sulfur dichloride. Sulfur coupled phenols, also referred to as polyphenol sulfides, are generally prepared by reacting a sulfur halide with a phenol at a temperature from about 50°C to about 75°C. The diluent as described above may also be used.

In a preferred embodiment, the phenol is substi- tuted with one of the polyalkene groups described above. Preferably, the phenol has a polybutene or polypropylene substituent having a number average molecular weight of about 700 to about 1200 or 1300.

The phenols useful in making the overbased salts of the invention can be represented by the formula (R,)_a-Ar- (OH)_b/ wherein R_x is defined above; Ar is an aromatic group; a and b are independently numbers of at least one, the sum of a and b being in the range of two up to the number of displaceable hydrogens on the aromatic nucleus or nuclei of Ar. Preferably, a and b are independently numbers in the range of 1 to about 4, more preferably 1 to about 2. Rj and a are preferably such that there is an average of at least about 8 aliphatic carbon atoms provided by the Rj groups for each phenol compound. While the term "phenol" is used herein, it is to be understood that this term is not intended to limit the aromatic group of the phenol to benzene. Accordingly, it is to be understood that the aromatic group as represented by "Ar", as well as elsewhere in other formulae in this specification and in the appended claims, can be mononucle- ar such as a phenyl, a pyridyl, or a thienyl, or polynucle¬ ar. The polynuclear groups can be of the fused type wherein an aromatic nucleus is fused at two points to another nucleus such as found in naphthyl, anthranyl, etc. The polynuclear group can also be of the linked type wherein at least two nuclei (either mononuclear or polynu¬ clear) are linked through bridging linkages to each other. These bridging linkages can be chosen from the group consisting of alkylene linkages, ether linkages, keto linkages, sulfide linkages, polysulfide linkages of 2 to about 6 sulfur atoms, etc.

The number of aromatic nuclei, fused, linked or both, in Ar can play a role in determining the integer values of a and b. For example, when Ar contains a single aromatic nucleus, the sum of a and b is from 2 to 6. When Ar contains two aromatic nuclei, the sum of a and b is from 2 to 10. With a tri-nuclear Ar moiety, the sum of a and b is from 2 to 15. The value for the sum of a and b is limited by the fact that it cannot exceed the total number of displaceable hydrogens on the aromatic nucleus or nuclei of Ar.

The promoters, that is, these materials which facilitate the incorporation of excess metal into the overbased material act to improve contact between the acidic material and the acidic organic compound (overbasing substrate) . Generally, the promoter is a material which is slightly acidic and able to form a salt with the basic metal compound. The promoter must also be an acid weak enough to be displaced by the acidic material, usually carbon dioxide. Generally, the promoter has a pKa in the range from about 7 to about 10. A particularly comprehen¬ sive discussion of suitable promoters is found in U.S. Patents 2,777,874, 2,695,910, 2,616,904, 3,384,586 and 3,492,231. These patents are incorporated by reference for their disclosure of promoters. In one embodiment, promot¬ ers include the phenolic promoters. Phenolic promoters include a variety of hydroxy-substituted benzenes and naphthalenes. A particularly useful class of phenols are the alkylated phenols of the type listed in U.S. Patent 2,777,874, e.g., heptylphenols, octylphenols, and nonyl- phenols. Mixtures of various promoters are sometimes used. The inorganic or lower carboxylic acidic materi¬ als, which are reacted with the mixture of promoter, basic metal compound, reaction medium and acidic organic com- pound, are disclosed in the above cited patents, for example, U.S. Patent 2,616,904. Included within the known group of useful acidic materials are lower carboxylic acids, having from 1 to about 8, preferably l to about 4 carbon atoms. Examples of these acids include formic acid, acetic acid, propanoic acid, etc., preferably acetic acid. Useful inorganic acidic compounds include HC1, S0₂, S0₃, C0₂, H₂S, N₂0₃, etc., are ordinarily employed as the acidic materials. Preferred acidic materials are carbon dioxide and acetic acid, more preferably carbon dioxide. The alkali metals present in the overbased alkali metal salts include principally lithium, sodium and potas¬ sium, with sodium being preferred. The overbased metal salts are prepared using a basic alkali metal compound. Illustrative of basic alkali metal compounds are hydrox- ides, oxides, alkoxides (typically those in which the alkoxy group contains up to 10 and preferably up to 7 carbon atoms), hydrides and amides of alkali metals. Thus, useful basic alkali metal compounds include sodium oxide, potassium oxide, lithium oxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium propoxide, lithium methoxide, potassium ethoxide, sodium butoxide, lithium hydride, sodium hydride, potassium hydride, lithium amide, sodium amide and potassium amide. Especially preferred are sodium hydroxide and the sodium lower alkoxides (i.e., those containing up to 7 carbon atoms) .

The overbased materials of the present invention may be prepared by methods known to those in the art. The methods generally involve adding acidic material to a reaction mixture comprising the hydrocarbyl-substituted acidic organic compound, the promoter and a basic alkali metal compound. These processes are described in the following U.S. Patent Nos.: 2,616,904; 2,616,905; 2,616,906; 3,242,080; 3,250,710; 3,256,186; 3,274,135; 3,492,231; and 4,230,586. These patents are incorporated herein by reference for these disclosures.

In the present invention, the hydrocarbyl-substi¬ tuted acidic organic materials have relatively high molecu¬ lar weights. Higher temperatures are generally used to promote contact between the acidic material, the acidic organic compound and the basic alkali metal compound. The higher temperatures also promote formation of the salt of the weakly acidic promoter by removal of water. In prepar¬ ing the overbased metal salts of the present invention, water must be removed from the reaction. The reaction generally proceeds at temperatures from about 100°C up to the decomposition temperature of the reaction mixture or the individual components of the reaction. The reaction may proceed at temperatures lower than 100°C, such as 60°C or above, if a vacuum is applied. Generally, the reaction occurs at a temperature from about 110°C to about 200°C, preferably 120°C to about 175°C and more preferably about 130°C to about 150°C. Preferably, the reaction is performed in the presence of a reaction medium which includes naphtha, mineral oil, xylenes, toluenes and the like. In the present invention water may be removed by applying a vacuum, by blowing the reaction mixture with a gas such as nitrogen or by removing water as an azeotrope, such as a xylene-water azeotrope. Generally, in the present invention, the acidic material is provided as a gas, usually carbon dioxide. The carbon dioxide, while participating in the overbasing process, also acts to remove water if the carbon dioxide is added at a rate which exceeds the rate carbon dioxide is consumed in the reac¬ tion. The overbased metal salts of the present inven¬ tion may be prepared incrementally (batch) or by continuous process. The incremental process involves the following steps: (A) adding a basic alkali metal compound to a reaction mixture comprising an acidic organic compound and removing free water from the reaction mixture to form an alkali metal salt of the acidic organic compound; (B) adding the basic alkali metal compound to the reaction mixture and removing free water from from the reaction mixture; and (C) introducing the acidic material to the reaction mixture while removing water. Steps (B) and (C) are repeated until a product of the desired metal ratio is obtained.

A novel aspect of the present invention is the semi-continuous process for preparing the alkali metal overbased salts of the present invention. The process involves (A) adding at least one basic alkali metal com¬ pound to a reaction mixture comprising an alkali metal salt of an acidic organic compound and removing free water from the reaction mixture; and (B) concurrently thereafter, (1) adding basic alkali metal compound to the reaction mixture; (2) adding an inorganic or lower carboxylic acidic material to the reaction mixture; and (3) removing water from the reaction mixture. The inventors have discovered that the addition of basic alkali metal compounds together with the inorganic or lower carboxylic acidic material may be accom¬ plished by a process where the addition is done continuous¬ ly along with the removal of water. This process shortens processing time of the reaction.

The term "free water" refers to the amount of water readily removed from the reaction mixture. This water is typically removed by azeotropic distillation. The water which remains in the reaction mixture is believed to be coordinated, associated, or solvated. The water may be in the form of water of hydration. Some basic alkali metal compounds may be delivered to the reaction mixture as aqueous solutions. The excess water added, or free water, with the basic alkali metal compound is usually then removed by azeotropic distillation, or vacuum stripping.

Water is generated during the overbasing process and is desirably removed as it is formed to minimize or eliminate formation of oil-insoluble metal carbonates. During the overbasing process above, the amount of water present prior to addition of the inorganic or lower carbox¬ ylic acidic material (steps (C) and (B-l) above) is less than about 30% by weight of the reaction mixture, prefera- bly 20%, more preferably 10%. Generally, the amount of water present after addition of the inorganic or lower carboxylic acidic material is up to about 4% by weight of the reaction mixture, preferably about 3%, more preferably about 2%.

When the process involves concurrent addition of basic alkali metal compounds and inorganic or lower carbox¬ ylic acidic materials, the hydrocarbyl group of the acidic organic compound is derived from the above-described poly- alkenes. The provisos related to the polyalkene of the sulfonic acid and mixture of acidic organic compound are only preferred embodiments.

In another embodiment, the alkali metal overbased salts are borated alkali metal overbased salts. Borated overbased metal salts are prepared by reacting a boron compound with the basic alkali metal salt. Boron compounds include boron oxide, boron oxide hydrate, boron trioxide, boron trifluoride, boron tribromide, boron trichloride, boron acid such as boronic acid, boric acid, tetraboric acid and metaboric acid, boron hydrides, boron amides and various esters of boron acids. The boron esters are preferably lower alkyl (1-7 carbon atoms) esters of boric acid. Preferably, the boron compounds are boric acid. Generally, the overbased metal salt is reacted with a boron compound at about 50°C to about 250°C, preferably 100°C to about 200°C. The reaction may be accomplished in the presence of a solvent such as mineral oil, naphtha, kero¬ sene, toluene or xylene. The overbased metal salt is reacted with a boron compound in amounts to provide at least about 0.5%, preferably about 1% up to about 5%, preferably about 4%, more preferably about 3% by weight boron to the composition.

The following examples illustrate the alkali metal overbased salts of the present invention and methods of making the same. In the examples and elsewhere in the specification, unless otherwise indicated, the temperature is degrees Celsius, the amounts are weight percent, and the pressure is atmospheric.

Example 1 A reaction vessel is charged with 1122 parts (2 equivalents) of a polybutenyl-substituted succinic anhy¬ dride derived from a polybutene , 105 parts (0.4 equivalent) of tetrapropenyl phenol, 1122 parts of xylene and 1000 grams of 100 neutral mineral oil. The mixture is stirred and heated to 80°C under nitrogen. Then, 580 parts of a 50% aqueous solution of sodium hydroxide is added to the vessel over 10 minutes. The mixture is heated from 80°C to 120°C over 1.3 hours. Water is removed by azeo¬ tropic reflux and the temperature rises to 150°C over 6 hours while 300 parts of water is collected. (1) The reaction mixture is cooled to 80°C where 540 parts of a 50% aqueous solution of sodium hydroxide is added to the vessel. (2) The reaction mixture is heated to 140°C over 1.7 hours and water is removed at reflux conditions. (3) The reaction mixture is carbonated at 1 standard cubic foot per hour (scfh) while removing water for 5 hours. Steps (l)-(3) are repeated using 560 parts of an aqueous sodium hydroxide solution. Steps (l)-(3) are repeated using 640 parts of an aqueous sodium hydroxide solution. Steps (1)- (3) are then repeated with another 640 parts of a 50% aqueous sodium hydroxide solution. The reaction mixture is cooled and 1000 parts of 100 neutral mineral oil are added to the reaction mixture. The reaction mixture is vacuum stripped to 115°C, about 30 millimeters of mercury. The residue is filtered through diatomaceous earth. The filtrate has a total base number of 361 (theoretical 398) , 43.4% sulfated ash (theoretical 50.3), 39.4% oil and a specific gravity of 1.11. Example 2 A reaction vessel is charged with 700 parts of a 100 neutral mineral oil, 700 parts (1.25 equivalents) of the succinic anhydride of Example 1 and 200 parts (2.5 equivalents) of a 50% aqueous solution of sodium hydroxide. The reaction mixture is stirred and heated to 80°C where 66 parts (0.25 equivalent) of tetrapropenyl phenol are added to the reaction vessel. The reaction mixture is heated from 80°C to 140°C over 2.5 hours with blowing of nitrogen and removal of 40 parts of water. Carbon dioxide (28 parts, 1.25 equivalents) is added over 2.25 hours at a temperature from 140-165°C. The reaction mixture is blown with nitrogen at 2 standard cubic foot per hour (scfh) and a total of 112 parts of water is removed. The reaction temperature is decreased to 115°C and the reaction mixture is filtered through diatomaceous earth. The filtrate has 4.06% sodium (theoretical 3.66), a total base number of 89, a specific gravity of 0.948 and 44.5% oil.

Example 3 A reaction vessel is charged with 281 parts (0.5 equivalent) of the succinic anhydride of Example 1, 281 parts of xylene, 26 parts of tetrapropenyl substituted phenol and 250 parts of 100 neutral mineral oil. The mixture is heated to 80°C and 272 parts (3.4 equivalents) of an aqueous sodium hydroxide solution are added to the reaction mixture. The mixture is blown with nitrogen at 1 scfh and the reaction temperature is increased to 148°C. The reaction mixture is then blown with carbon dioxide at 1 scfh for one hour and 25 minutes while 150 parts of water is collected. The reaction mixture is cooled to 80°C where 272 parts (3.4 equivalents) of the above sodium hydroxide solution is added to the reaction mixture and the mixture is blown with nitrogen at 1 scfh. The reaction temperature is increased to 140°C where the reaction mixture is blown with carbon dioxide at 1 scfh for 1 hour and 25 minutes while 150 parts of water is collected. The reaction temperature is decreased to 100°C and 272 parts (3.4 equivalents) of the above sodium hydroxide solution is added while blowing the mixture with nitrogen at 1 scfh. The reaction temperature is increased to 148°C and the reaction mixture is blown with carbon dioxide at 1 scfh for 1 hour and 40 minutes while 160 parts of water is collect¬ ed. The reaction mixture is cooled to 90°C and where 250 parts of 100 neutral mineral oil are added to the reaction mixture. The reaction mixture is vacuum stripped at 70°C and the residue is filtered through diatomaceous earth. The filtrate contains 50.0% sodium sulfate ash (theoretical 53.8%) by ASTM D-874, total base number of 408, a specific gravity of 1.18 and 37.1% oil. Example 4

A reaction vessel is charged with 700 parts of the product of Example 3. The reaction mixture is heated to 75^βC where 340 parts (5.5 equivalents) of boric acid is added over 30 minutes. The reaction mixture is heated to 110°C over 45 minutes and the reaction temperature is maintained for 2 hours. A 100 neutral mineral oil (80 parts) is added to the reaction mixture. The reaction mixture is blown with nitrogen at 1 scfh at 160°C for 30 minutes while 95 parts of water is collected. Xylene (200 parts) is added to the reaction mixture and the reaction temperature is maintained at 130-140°C for 3 hours. The reaction mixture is vacuum stripped at 150°C and 20 milli¬ meters of mercury. The residue is filtered through dia¬ tomaceous earth. The filtrate contains 5.84% boron (theo- retical 6.43) and 33.1% oil. The residue has a total base number of 309.

Example 5 A reaction vessel is charged with 224 parts (0.4 equivalents) of the succinic anhydride of Example 1, 21 parts (0.08 equivalent) of a tetrapropenyl phenol, 224 parts of xylene and 224 parts of 100 neutral mineral oil. The mixture is heated and 212 parts (2.65 equivalents) of a 50% aqueous sodium hydroxide solution are added to the reaction vessel. The reaction temperature increases to 130°C and 41 parts of water is removed by nitrogen blowing at 1 scfh. The reaction mixture is then blown with carbon dioxide at 1 scfh for 1.25 hours. The sodium hydroxide solution (432 parts, 5.4 equivalents) is added over four hours with carbon dioxide blowing at 0.5 scfh at 130°C. During the addition, 301 parts of water are removed from the reaction vessel. The reaction temperature is increased to 150°C and the rate of carbon dioxide blowing is in¬ creased to 1.5 scfh and maintained for 1 hour and 15 minutes. The reaction mixture is cooled to 150°C and blown with nitrogen at 1 scfh while 176 parts of oil is added to the reaction mixture. The reaction mixture is blown with nitrogen at 1.8 scfh for 2.5 hours and the mixture is then filtered through diatomaceous earth. The filtrate contains 15.7% sodium and 39% oil. The filtrate has a total base number of 380.

Example 6

A reaction vessel is charged with 561 parts (1 equivalent) of the succinic anhydride of Example 1, 52.5 parts (0.2 equivalent) of a tetrapropenylphenol, 561 parts xylene and 500 parts of a 100 neutral mineral oil. The mixture is heated to 50°C under nitrogen and 373.8 parts

(6.8 equivalents) of potassium hydroxide and 299 parts of water are added to the mixture. The reaction mixture is heated to 135°C while 145 parts of water is removed. The azeotropic distillate is clear. Carbon dioxide is added to the reaction mixture at 1 scfh for two hours while 195 parts of water is removed azeotropically. The reaction is cooled to 75°C where a second portion of 373.8 parts of potassium hydroxide and 150 parts of water are added to the reaction vessel. The reaction mixture is heated to 150°C with azeotropic removal of 70 parts of water. Carbo dioxide (1 scfh) is added for 2.5 hours while 115 parts of water is removed azeotropically. The reaction is cooled to 100°C where a third portion of 373.8 parts of potassiu hydroxide and 150 parts of water is added to the vessel. The reaction mixture is heated to 150°C while 70 parts of water is removed. The reaction mixture is blown with carbon dioxide at 1 scfh for one hour while 30 parts of water is removed. The reaction temperature is decreased to 70°C. The reaction mixture is reheated to 150°C under nitrogen. At 150°C the reaction mixture is blown with carbon dioxide at 1 scfh for two hours while 80 parts of water is removed. The carbon dioxide is replaced with a nitrogen purge and 60 parts of water is removed. The reaction is then blown with carbon dioxide at 1 scfh for three hours with removal of 64 parts of water. The reac¬ tion mixture is cooled to 75°C where 500 parts of 100 neutral mineral is added to the reaction mixture. The reaction is vacuum stripped to 115°C and 25 millimeters of mercury. The residue is filtered through diatomaceous earth. The filtrate contains 35% oil and has a base number of 322.

Example 7 An overbased sodium salt of a substituted phenol is prepared by the process of Example 1 using 994 parts (1 equivalent) of polybutenyl-substituted phenol derived from a polybutene (Mn=900) reacted with 1440 (18 equivalents) of a 50% aqueous solution of sodium hydroxide.

Example 8 An overbased sodium sulfonate is prepared by the process described in Example 6 by using 980 parts (1 equivalent) of a sodium polypropenyl-substituted benzene sulfonate derived from a polypropene (Mn=800) and 800 parts (10 equivalents) of a 50% aqueous solution of sodium hydroxide. Example 9 An overbased lithium carboxylate is prepared by the process described in Example 1 using 1072 parts (1 equivalent) of a polybutenyl of carboxylate, prepared by reacting polybutenyl chloride derived from a polybutene (Mn=1000) and acrylic acid, which is reacted with 756 parts (18 equivalents) of lithium hydroxide monohydrate.

Example 10 An overbased sodium sulfonate-carboxylate is prepared by the process described in Example 1 using 562 parts of the succinic anhydride of Example 1 and 479 parts of a polybutenyl-substituted sulfonic acid derived from a polybutene and 1632 parts (20.4 equivalents) of a 50% aqueous solution of sodium hydroxide. Lubricating Compositions

The alkali metal overbased salts of the present invention may be used, in lubricants or in concentrates, by themselves or in combination with any other known additive which includes, but is not limited to dispersants, deter- gents, antioxidants, anti-wear agents, extreme pressure agents, emulsifiers, demulsifiers, foam inhibitors, fric¬ tion modifiers, anti-rust agents, corrosion inhibitors, viscosity improvers, pour point depressants, dyes, and solvents to improve handleability which may include alkyl and/or aryl hydrocarbons. These additives may be present in various amounts depending on the needs of the final product.

Dispersants include, but are not limited to, hydrocarbon substituted succinimides, succinamides, carbox- ylic esters, Mannich dispersants and mixtures thereof as well as materials functioning both as dispersants and viscosity improvers. The dispersants include nitrogen- containing carboxylic dispersants, ester dispersants, Mannich dispersants or mixtures thereof. Nitrogen-contain- ing carboxylic dispersants are prepared by reacting a hydrocarbyl carboxylic acylating agent (usually a hydro¬ carbyl substituted succinic anhydride) with an amine (usually a polyamine) . Ester dispersants are prepared by reacting a polyhydroxy compound with a hydrocarbyl carbox- ylic acylating agent. The ester dispersant may be further treated with an amine. Mannich dispersants are prepared by reacting a hydroxy aromatic compound with an amine and aldehyde. The dispersants listed above may be post-treated with reagents such as urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon substi¬ tuted succinic anhydride, nitriles, epoxides, boron com¬ pounds, phosphorus compounds and the like.

Detergents include, but are not limited to, Newtonian or non-Newtonian, neutral or basic salts of alkaline earth or transition metals with one or more hydrocarbyl sulfonic acid, carboxylic acid, phosphoric acid, thiophosphoric acid, dithiophosphoric acid, phos- phinic acid, thiophosphinic acid, sulfur coupled phenol or phenol. Basic salts are salts that contain a stoichiomet- ric excess of metal present per acid function.

Auxiliary extreme pressure agents and corrosion- and oxidation-inhibiting agents which may be included in the lubricants of the invention are exemplified by chlori¬ nated aliphatic hydrocarbons such as chlorinated wax; organic sulfides and polysulfides such as benzyl disulfide, bis(chlorobenzyl)disulfide, dibutyl tetrasulfide, sulfu- rized methyl ester of oleic acid, sulfurized alkylphenol, sulfurized dipentene, and sulfurized terpene; phospho- sulfurized hydrocarbons such as the reaction product of a phosphorus sulfide with turpentine or methyl oleate, phosphorus esters including principally dihydrocarbon and trihydrocarbon phosphites such as dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite, dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite, dimethyl naphthyl phosphite, oleyl 4-pentylphenyl phosphite, polypropylene (molecular weight 500)-substituted phenyl phosphite, diisobutyl-substituted phenyl phosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate, and barium heptylphenyl dithio- carbamate; boron-containing compounds including borate esters; molybdenum compounds; Group II metal phosphorodi- thioates such as zinc dicyclohexylphosphorodithioate, zinc dioctylphosphorodithioate, barium di(heptylphenyl)-phos- phorodithioate, cadmium dinonylphosphorodithioate, and the zinc salt of a phosphorodithioic acid produced by the reaction of phosphorus pentasulfide with an equimolar mixture of isopropyl alcohol and n-hexyl alcohol.

Viscosity improvers include, but are not limited to, polyisobutenes, polymethacrylate acid esters, poly- aerylate acid esters, diene polymers, polyalkyl styrenes, alkenyl aryl conjugated diene copolymers, polyolefins and multifunctional viscosity improvers.

Pour point depressants are a particularly useful type of additive often included in the lubricating oils described herein. See for example, page 8 of "Lubricant

Additives" by C. V. Smalheer and R. Kennedy Smith (Lesius-

Hiles Company Publishers, Cleveland, Ohio, 1967) .

Anti-foam agents used to reduce or prevent the formation of stable foam include silicones or organic polymers. Examples of these and additional anti-foam compositions are described in "Foam Control Agents", by Henry T. Kerner (Noyes Data Corporation, 1976) , pages 125- 162.

These and other additives are described in greater detail in U.S. Patent 4,582,618 (column 14, line 52 through column 17, line 16, inclusive), herein incorporated by reference for its disclosure of other additives that may be used in combination with the present invention.

The concentrate might contain 0.01 to 90% by weight of the alkali metal overbased salts. The alkali metal overbased salts may be present in a final product, blend or concentrate in (in a minor amount, i.e., up to 50% by weight) any amount effective to act as a detergent, bu is preferably present in oil of lubricating viscosity, hydraulic oils, fuel oils, gear oils or automatic transmis¬ sion fluids in an amount of from about 0.1 to about 10%, preferably 0.25 to about 2% by weight, most preferably about 0.50 to about 1.25%.

The lubricating compositions and methods of this invention employ an oil of lubricating viscosity, including natural or synthetic lubricating oils and mixtures thereof. Natural oils include animal oils, vegetable oils, mineral lubricating oils, solvent or acid treated mineral oils, and oils derived from coal or shale. Synthetic lubricating oils include hydrocarbon oils, halo-substituted hydrocarbon oils, alkylene oxide polymers, esters of carboxylic acids and polyols, esters of polycarboxylic acids and alcohols, esters of phosphorus-containing acids, polymeric tetra- hydrofurans, silicon-based oils and mixtures thereof. Specific examples of the oils of lubricating viscosity are described in U.S. Patent 4,326,972 and European Patent Publication 107,282, both herein incorpo¬ rated by reference for their disclosures relating to lubricating oils. A basic, brief description of lubricant base oils appears in an article by D. V. Brock. "Lubricant Base Oils", Lubricant Engineering:, volume 43, pages 184- 185, March, 1987. This article is herein incorporated by reference for its disclosures relating to lubricating oils. A description of oils of lubricating viscosity occurs in U.S. Patent 4,582,618 (column 2, line 37 through column 3, line 63, inclusive), herein incorporated by reference for its disclosure to oils of lubricating viscosity.

The following examples illustrate lubricating compositions of the present invention. The amount of each component in Examples A-C reflects the amount of oil containing product of the indicated additives.

Lubricant (% weight)

Component A B C

Product of Example 1 0.76 1.04 1.04

Reaction product of poly¬ 5.7 6.25 6.25 butene succinic anhydride (Polybutene Mn=1845) and ethylene polyamines

Zinc-isopropyl,methylamyl 0.9 1.12 1.12 dithiophosphate

Methylene-bis(6-t-butyl- 0.33 0.32 4-tetrapropenyl phenol)

2,6-di-t-butyl-4-tetra¬ 0.37 propenyl phenol

Copper-0,0'isopropyl, 0.08 0.1 0.1 methylamyl dithiophosphate

Glycerolmonooleate or 0.1 0.1 0.1 oleylamide

8% by weight hydrogenated 9.5 9.0 10.0 styrene-butadiene copolymer in 100 neutral mineral oil

Silicon antifoam agent 80 ppm 80 ppm 80 ppm

Oil Balance Balance Balance

The lubricating oil compositions of the present invention exhibit a reduced tendency to deteriorate under conditions of use and thereby reduce rust and corrosive wear and the formation of such undesirable deposits as varnish, sludge, carbonaceous materials and resinous materials which tend to adhere to the various engine parts and reduce the efficiency of the engines. Lubricating oils also can be formulated in accordance with this invention which result in improved fuel economy when used in the crankcase of a passenger automobile.

While the invention has been explained in rela¬ tion to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Claims

Claims 1. A composition, comprising: at least one basic alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl group is derived from a polyalkene having an Mn of at least 600, provided that when the organic compound is a sulfonic acid, the polyalkene has an Mn of at least 900; and provided that when the acidic organic compound is a mixture of acidic organic compounds containing a carboxylic acid and a sulfonic acid which has a hydrocarbyl group derived from a polyalkene having an Mn of less than 900, then the carboxylic acid comprises at least 10% of the acid equivalents of the mixture.

2. The composition of claim 1, wherein the basic salt has a metal ratio from about 1.5 to about 40.

3. The composition of claim 1, wherein the polyalkene has an Mn from about 800 to about 3,000.

4. The composition of claim 1, wherein the polyalkene has an Mn from about 900 to about 1,500.

5. The composition of claim 1, wherein the polyalkene is polybutene.

6. The composition of claim 1, wherein the acidic organic compound is a sulfonic or carboxylic acid.

7. The composition of claim 1, wherein the metal salt is a sodium or potassium salt.

8. The composition of claim 1, wherein the overbased salt is an overbased succinate.

9. The composition of claim 1, wherein the overbased salt is a sodium overbased succinate.

10. A basic alkali metal salt of a hydrocarbyl- substituted acidic organic compound, prepared by the process comprising:

(A) adding a portion of (A-l) at least one basic alkali metal compound to a reaction mixture comprising (A- 2) at least one alkali metal salt of a hydrocarbyl-substi¬ tuted acidic organic composition, wherein the hydrocarbyl group is derived from a polyalkene having a number average molecular weight of at least 600, provided that when the organic composition is a sulfonic acid, the polyalkene has a number average molecular weight of at least 900, and provided that when the acidic organic composition is a mixture of acidic organic compounds, containing a carboxyl¬ ic acid and a sulfonic acid which has a hydrocarbyl group derived from a polyalkene having an Mn of less than 900, then the carboxylic acid comprises at least 10% of the equivalents of the mixture and removing free water from the reaction mixture; and thereafter (B) concurrently (1) adding at least one basic alkali metal compound to the reaction mixture,

11. The composition of claim 10, wherein the hydrocarbyl group is derived from a polyalkene having a number average molecular weight of about 900 to about 1500.

12. The composition of claim 10, wherein the salt has a metal ratio of about 1.5 to about 40.

13. The composition of claim 10, wherein the acidic organic compound is a carboxylic acid or anhydride.

14. The composition of claim 10, wherein the basic alkali metal compound is a basic sodium or potassium compound.

15. The composition of claim 10, wherein the promoter has a pKa from about 7 to about 10.

16. The composition of claim 10, wherein the promoter is an alkyl or alkenyl phenol or nitroalkane.

17. A lubricating composition, comprising a major amount of an oil of lubricating viscosity and the composition of claim 1.

18. A lubricating composition, comprising a major amount of an oil of lubricating viscosity and the composition of claim 10.

19. The composition of claim 17, wherein the lubricating composition further comprises (B) at least one dispersant.

20. The composition of claim 19, wherein (B) the dispersant is (a) at least one nitrogen-containing carbox¬ ylic dispersant, (b) at least one ester dispersant, (c) at least one Mannich dispersant, (d) at least one post-treated dispersant, or mixtures of two or more thereof.

21. The composition of claim 19, wherein the lubricating composition further comprises (C) at least one metal dihydrocarbyl dithiophosphate.

22. The composition of claim 20, wherein the metal dihydrocarbyl dithiophosphate (C) is at least one zinc dihydrocarbyl dithiophosphate.

23. A process for preparing basic alkali metal salts of acidic organic compounds, comprising

(A) adding a portion of at least one basic alkali metal compound to a reaction mixture comprising at least one alkali metal salt of a hydrocarbyl-substituted acidic organic composition and removing free water from the reaction mixture; and

(B) concurrently, thereafter

(1) adding at least one basic alkali metal compound to the reaction mixture,

24. The process of claim 23, wherein the react¬ ing occurs at a temperature of about 110°C to about 200°C.

25. The process of claim 23, wherein the react¬ ing occurs at a temperature from about 130°C to about 150°C.

26. The process of claim 23, wherein the promot¬ er is an alkyl or alkenyl phenol or a nitroalkane.

27. The process of claim 23, wherein the basic alkali metal compound is a basic sodium compound.

28. The process of claim 23, wherein the acidic organic composition contains at least one carboxylic acid.

29. The process of claim 23, wherein the hydro¬ carbyl group is derived from a polyalkene having an Mn of at least 600.