WO2001074751A2 - Lubricating oil compositions containing saligenin derivatives - Google Patents

Abstract

A saligenin derivative such as the magnesium salt of a polynuclear bridged phenol product is useful as an additive for a lubricating composition. Up to 11 hydrocarbyl-substituted phenolic aromatic units are bridged by -CH2- or -CH2OCH2 groups, and additional terminal -CHO or -CH2OH substituents may be present. At least one aromatic ring contains a hydrocarbyl substituent of 1 to 60 carbon atoms, and the total number of carbon atoms in all such hydrocarbyl groups should be at least 7.

Description

Title: LUBRICATING OIL COMPOSITIONS CONTAINING SALIGENIN DERIVATIVES Cross-reference to Related Applications This Application claims priority from U.S. Provisional Application

Serial No. 60/194,136, filed April 3, 2000.

Field of the Invention The present invention provides certain saligenin derivatives used in lubricating compositions. Heavy duty diesel engine oil formulations that con- tain, especially, borated or non-borated magnesium saligenin derivatives of the present invention exhibit significantly improved seal compatibility and reduced copper and lead corrosion. They also exhibit improved upper piston deposit performance, which can minimize excessive oil consumption and piston scuffing and can improve engine life. Background of the Invention

Saligenin, also known as salicyl alcohol and o-hydroxybenzyl alcohol, is represented by the structure

U.S. Patent No. 2,250,188 (Wilson, July 22, 1941) relates to mineral lubricating oils modified by addition of constituents to impart characteristics adapting them to conditions such as found in Diesel engines. In the lubricating oil is dissolved a small quantity of the calcium or other oil-soluble salt of the condensation product of formaldehyde with an alkyl phenol in which the alkyl group contains preferably 4 or 5 carbon atoms to insure oil solubility. Other metals than calcium, particularly the other alkaline earth metals and the light metals aluminum and zinc, may be employed in the formation of the oil- soluble metal salts: U.S. Patent No. 3,256,183 (Greenwald, June 14, 1966) relates to lubricant compositions for use in engines of the diesel type, which include, among other components, an oil-soluble calcium phenate compound prepared by the process comprising the steps of reacting a mixture comprising 1 mole of an alkyl phenol and from about 1 to about 2 moles of a formaldehyde producing reagent in the presence of a catalyst at a temperature of from about 10°C to about 99°C and thereafter reacting said mixture with a calcium reagent selected from the class consisting of calcium hydroxide and calcium oxide at a temperature of at least about 30°C.

U.S. Patent No. 5,516,441 (Denis, May 14, 1996) relates to a metal salt or boron compound of a hydrocarbyl-substituted aromatic hydroxy compound having at least two hydroxy-substituted aromatic rings bridged by sulfur, where at least one aromatic ring bears a substituent ortho to a hydroxy group, provides a useful lubricant additive. The substituent on the aromatic ring is an α-hydroxy aliphatic hydrocarbyl group or a -C(O)R² group, where R² is hydrogen or aliphatic hydrocarbyl. Reaction of aldehyde with the sulfur-coupled aromatic hydroxy compound should be conducted under non-condensing conditions. Preferred salts are magnesium.

Summary of the Invention

The present invention provides a composition comprising a saligenin derivative represented by the formula

wherein each X independently is -CHO, or -CH₂OH, each Y independently is -CH₂- or -CH₂OCH₂-, and wherein such -CHO groups comprise at least 10 mole percent of the X and Y groups; each M is independently hydrogen, ammonium, or a valence of a metal ion; each R¹ is independently a hydrocarbyl group containing 1 to 60 carbon atoms; m is 0 to 10; and each p is independently 0, 1, 2, or 3; provided that at least one aromatic ring contains an R¹ substituent and that the total number of carbon atoms in all R¹ groups is at least 7; further provided that if m is 1 or greater, then one of the X groups can be -H. The invention further provides a lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount of the above saligenin derivative.

The invention further provides a process for preparing a saligenin derivative as above, particularly where M is magnesium, comprising combining a phenol substituted by said R¹ group with formaldehyde or a source of formaldehyde and magnesium oxide or magnesium hydroxide under reactive conditions, in the presence of a catalytic amount of a strong base; wherein the equivalent ratio of the substituted phenol to formaldehyde or source thereof is 1: 1 to 1 :4; whereby the saligenin derivative is formed such that X is at least in part -CHO and such -CHO groups comprise at least 10% of the X and Y groups.

Brief Description of the Figure Figure 1 is a triangular composition plot showing preferred compositions of the saligenin component in terms of relative amounts of three of its X and Y substituents, -CHO, -CH₂OH, and -CH₂-.

Detailed Description of the Invention The present invention comprises a saligenin derivative which can be used as a component of a lubricating composition which comprises an oil of lubricating viscosity and, optionally, other additives. Oil of Lubricating Viscosity

The diverse oils of lubricating viscosity include natural and synthetic lubricating oils and mixtures thereof. These lubricants include crankcase lubricating oils for spark-ignited and compression-ignited internal combustion engines, including automobile and truck engines, two-cycle engines, aviation piston engines, and marine and railroad diesel engines. They can also be used in gas engines, stationary power engines, and turbines. 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. Natural oils include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils. Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, pro- pylene-isobutylene copolymers, poly(l-hexenes, poly(l-octenes), poly(l- decenes), and mixtures thereof); alkylbenzenes (e.g., dodecylbenzenes, tetra- decylbenzenes, dinonylbenzenes, and di(2-ethylhexyl)-benzenes); polyphenyls (e.g., biphenyls, terphenyls, and alkylated polyphenyls), alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs, and ho- mologs thereof.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, or similar reaction constitute another class of known synthetic lubricating oils. These are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methylpolyisopropylene glycol ether having an average molecular weight of 1,000 diphenyl ether of polyethylene glycol having a molecular weight of 500-1,000, diethyl ether of polypropylene glycol having a molecular weight of 1,000-1,500) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C₃-C₈ fatty acid esters, or the C₁₃ Oxo acid diester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, and alkenyl malonic acids) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific examples of these esters include dibutyl adipate, di (2-ethylhexyl sebacate, di-n-hexyl fuma- rate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid. Esters useful as synthetic oils also include those made from C₅ to ₂ monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol.

Unrefined, refined and rerefined oils (and mixtures of each with each other) of the type disclosed hereinabove can be used in the lubricant compositions of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation or ester oil obtained directly from an esteri- fication process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except that they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those of skill in the art such a solvent extraction, acid or base extraction, filtration, percolation, or similar purification techniques. Rerefined oils are obtained by processes similar to those used to obtain refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products. The aliphatic and alicyclic substituents, as well as aryl nuclei, are generally described as "hydrocarbon-based". The meaning of the term "hydrocarbon-based" as used herein is apparent from the following detailed discussion of "hydrocarbon-based substituent."

As used herein, the terms "hydrocarbon-based substituent," "hydrocarbyl substituent" or "hydrocarbyl group," which are used synonymously, are used in their ordinary sense, which is well-known to those skilled in the art. Specifically, any of these terms refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: (1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicy- clic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form a ring); (2) substituted hydrocarbon substituents, that is, substituents containing non- hydrocarbon groups which, in the context of this invention, do not alter the predomi- nantly hydrocarbon substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);

(3) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non- hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocar- byl group.

Preferably, the hydrocarbon-based substituents in the compositions of this invention are free from acetylenic unsaturation. Ethylenic unsaturation, when present, preferably will be such that no more than one ethylenic lineage will be present for every 10 carbon-to-carbon bonds in the substituent. The hydrocarbon-based substituents are usually hydrocarbon in nature and more usually, substantially saturated hydrocarbon. As used in this specification and the appended claims, the word "lower" denotes substituents or groups containing up to seven carbon atoms; for example, lower alkoxy, lower alkyl, lower alkenyl, lower aliphatic aldehyde. (A) The Saligenin Derivative

The saligenin derivative of the present invention can be represented by the formula

where M is hydrogen, ammonium, or a valence of a metal ion, and the identity, description, and amounts of other symbols are as described below. Generally speaking if M is a metal it is not particularly limited but can be, for instance, an alkali metal such as lithium, sodium, or potassium; an alkaline earth metal

- such as magnesium, calcium, or barium; and other metals such as copper, zinc, and tin, or mixtures thereof. Ammonium ions can be the unsubstituted ammo- niu ion, NH₄ ⁺ or amine ions in which one or more of the hydrogens are replaced by hydrocarbyl groups. Preferably M is calcium or magnesium, most preferably magnesium.

The preferred magnesium salt can be represented more particularly by the formula

In this embodiment, (Mg) represents a valence of a magnesium ion. (Other valences of the normally divalent Mg ion, not shown, can be satisfied by other anions or by association with additional -O^~ functionality of the same or additional saligenin derivatives.) Each n is independently 0 or 1, provided that when n is 0, the Mg is replaced by H, that is, to form an unneutralized phenolic -OH group. The average value of n in the composition overall is typically 0.1 to 1.0. That is, the structure represents a partially or completely neutralized magnesium salt, a value of 1.0 corresponding to complete neutralization of each site by the divalent Mg ion. The compound contains one aromatic ring or a multiplicity of aromatic rings linked by "Y" groups, and also "X" groups. Since "m" can be 0 to 10, this means that the number of such rings will typically be 1 to 11, although it is to be understood that the upper limit of "m" is not a critical variable. Preferably m is 2 to 9, more preferably 3 to 8 or 4 to 6. If m is 1 or greater, then one of the X groups can be -H.

Most of the rings contain at least one R¹ substituent, which is a hydrocarbyl group, preferably an alkyl group, containing 1 to 60 carbon atoms, preferably 7 to 28 carbon atoms, more preferably 9 to 18 carbon atoms. Of course it is understood that R¹ will normally comprise a mixture of various chain lengths, so that the foregoing numbers will normally represent an average number of carbon atoms in the R¹ groups (number average). R¹ can be linear or branched. Each ring in the structure will be substituted with 0, 1, 2, or 3 such R¹ groups (that is, p is 0, 1, 2, or 3), most typically 1, and of course different rings in a given molecule may contain different numbers of such substituents. At least one aromatic ring in the molecule must contain at least one R¹ group, and the total number of carbon atoms in all the R¹ groups in the molecule should be at least 7, preferably at least 12.

In the above structure the X and Y groups may be seen as groups derived from formaldehyde or a formaldehyde source, by condensative reaction with the aromatic molecule. While various species of X and Y may be present in the molecules in question, the commonest species comprising X are -CHO (aldehyde functionality) and -CH₂OH (hydroxymethyl functionality); similarly the commonest species comprising Y are -CH₂- (methylene bridge) and -CH₂OCH₂- (ether bridge). The relative molar amounts of these species in a sample of the above material can be determined by ¹H/¹³C NMR as each carbon and hydrogen nucleus has a distinctive environment and produces a distinctive signal. (The signal for the ether linkage, -CH₂OCH₂- must be corrected for the presence of two carbon atoms, in order to arrive at a correct calculation of the molar amount of this material. Such a correction is well within the abilities of the person skilled in the art.)

In a preferred embodiment, X is at least in part -CHO and such -CHO groups comprise at least 10, 12, or 15 mole percent of the X and Y groups. Preferably the -CHO groups comprise 20 to 60 mole percent of the X and Y groups and more preferably 25 to 40 mole percent of the X and Y groups. In another embodiment, X is at least in part -CH₂OH and such -CH₂OH groups comprise 10 to 50 mole percent of the X and Y groups, preferably 15 to 30 mole percent of the X and Y groups.

In an embodiment in which m is non-zero, Y is at least in part -CH₂- and such -CH₂- groups comprise 25 to 55 mole percent of the X and Y groups, preferably 32 to 45 mole percent of the X and Y groups.

In another embodiment Y is at least in part -CH₂OCH₂- and such -CH₂OCH₂- groups comprise 5 to 20 mole percent of the X and Y groups, and preferably 10 to 16 mole percent of the X and Y groups.

The relative amounts of the various X and Y groups depends to a cer- tain extent on the conditions of synthesis of the molecules. Under many conditions the amount of -CH₂OCH₂- groups is relatively small compared to the other groups and is reasonably constant at about 13 to 17 mole percent. Ignoring the amount of such ether groups and focusing on the relative amounts of the -CHO, -CH₂OH, and -CH₂- groups, it has been found that particularly preferred compositions have the following relative amounts of these three groups, the total of such amounts in each case being normalized to equal 100%:

-CHO : 15-100 %, preferably 20-60 %, most preferably 25-50 % -CH₂OH : 0-54 % 4 - 46 % " 10-40 %

-CH₂- : 0-64 % " 18-64 % " 20-60 %

Alternatively preferred proportions can be taken from the triangular composition diagram shown in Figure 1. In this diagram, vertex L represents a compo- sition containing 100% aldehyde functionality (normalized as above), vertex H represents a composition containing 100% hydroxymethyl functionality, and vertex M represents a composition containing 100% methylene functionality. A generally preferred group of compositions of the present invention fall within the area designated "A," more preferred compositions fall within the area designated "B," and highly preferred compositions fall within the area designated "C." For comparative purposes, a dot (•) located in the lower right corner of the triangle represents a typical (comparative) composition of a conventional calcium phenol-formaldehyde reaction product.

The above-described compound is preferably a magnesium salt and, indeed, the presence of magnesium during the preparation of the condensed product is believed to be important in achieving the desired ratios of X and Y components described above. (After preparation of the compound, the Mg metal can be replaced by hydrogen, other metals, or ammonium if desired, by known methods.) The number of Mg ions in the composition is characterized by an average value of "n" of 0.1 to 1.0, preferably 0.2 or 0.4 to 0.9, and more preferably 0.6 to 0.8, which correspond to 20-100%, 20 or 40-90%, or 60-80% neutralization by Mg. Since Mg is normally a divalent ion, it can neutralize up to two phenolic hydroxy groups. Those two hydroxy groups may be on the same or on different molecules. If the value of n is less than 1.0, this indicates that the hydroxy groups are less than completely neutralized by Mg ions. Alternatively, each Mg ion could be associated with one phenolic anion and an ion of another type such as a hydroxy (OH^") ion or carbonate ion (CO₃ ^"), while still providing an n value of 1.0. The specification that the average value of n is 0.1 to 1.0 is not directly applicable to overbased versions of this material (described below and also a part of the present invention) in which an excess of Mg or another cation can be present. It should be understood that, even in an overbased material, some fraction of the phenolic OH groups may not have reacted with the magnesium and may retain the OH structure.

It is understood that in a sample of a large number of molecules, some individual molecules will exist which deviate from these parameters: for in- stance, there may be some molecules containing no R¹ groups whatsoever. Likewise, some fraction of molecules may contain only one (or even zero) X groups, while some may contain more than two X groups. And some fraction of the aromatic groups may be linked by Y groups to more than two neighboring aromatic groups. These molecules could be considered as impurities, and their presence will not negate the present invention so long as the majority (and preferably the substantial majority) of the molecules of the composition are as described. In any event, compositions exhibiting this type of variability are to be construed as encompassed by the present invention and the description that a material is "represented by" the formula shown. There is believed to be a reasonable possibility that a significant fraction of the polynuclear molecules of the present invention may bear only a single X group. In order to explicitly account for this possibility, it is to be understood that in the materials of an embodiment of the present invention, if m is 1 or greater, one (but preferably not both) of the X groups in the above structures can be -H. The above-described component can be prepared by combining a phenol substituted by the above-described R¹ group with formaldehyde or a source of formaldehyde and magnesium oxide or magnesium hydroxide under reactive conditions, in the presence of a catalytic amount of a strong base.

Substituted phenols, and alkyl-substituted phenols in particular, are well known items of commerce. Alkylated phenols are described in greater detail in U.S. Patent 2,777,874.

Formaldehyde and its equivalents are likewise well known. Common reactive equivalents of formaldehyde includes paraformaldehyde, trixoane, formalin and methal. For convenience, paraformaldehyde is preferred. The relative molar amounts of the substituted phenol and the formaldehyde can be important in providing products with the desired structure and properties. It is preferred that the substituted phenol and formaldehyde are reacted in equivalent ratios of 1: 1 to 1:3 or 1:4, more preferably 1: 1.1 to 1:2.9 or 1: 1.4 to 1 :2.6, and still more preferably 1: 1.7 to 1 :2.3. Thus under preferred conditions there will be about a 2: 1 equivalent ratio of formaldehyde. (One equivalent of formaldehyde is considered to correspond to one H CO unit; one equivalent of phenol is considered to be one mole of phenol.)

The strong base is preferably sodium hydroxide or potassium hydroxide, and can be supplied in an aqueous solution. The process can be conducted by combining the above components with an appropriate amount of magnesium oxide or magnesium hydroxide with heating and stirring. A diluent such as mineral oil or other diluent oil can be included to provide for suitable mobility of the components. An additional solvent such as an alcohol can be included if desired, although it is believed that the reaction may proceed more efficiently in the absence of additional solvent. The reaction can be conducted at room temperature or, preferably, a slightly elevated temperature such as 35-120°C, 70-110°C, or 90-100°C, and of course the temperature can be increased in stages. When water is present in the reaction mixture it is convenient to maintain the mixture at or below the normal boiling point of water. After reaction for a suitable time (e.g., 30 minutes to 5 hours or 1 to 3 hours) the mixture can be heated to a higher temperature, preferably under reduced pressure, to strip off volatile materials. Favorable results are obtained when the final temperature of this stripping step is 100 to 150°C, preferably 120 to 145°C. Reaction under the preferred conditions described above leads to a product which has a relatively high content of -CHO substituent groups, that is, 10%, 12%, 15%, or greater. Such materials, when used as detergents in lubricating compositions, exhibit good upper piston cleanliness performance, low Cu/Pb corrosion, and good compatibility with seals. Use of metals other than magnesium in the synthesis typically leads to a reduction in the content of -CHO substituent groups. Example 1.

To a 5-L, 4-necked round bottom flask equipped with stirrer, stopper, thermowell, and reflux condenser, the following are charged: 670 g diluent oil (mineral oil), 1000 g dodecyl phenol, and a solution of 3 g NaOH in 40 g water. The mixture is heated to 35°C with stirring (350 r.p.m.). When 35°C is attained, 252 g of paraformaldehyde (90%) are added to the mixture and stirring is continued. After 5 minutes, 5 g of MgO and 102 g of additional diluent oil are added. The mixture is heated to 79°C and held at temperature for 30 minutes. A second increment of 58 g MgO is added and the batch further heated and maintained at 95-100°C for 1 hour. Thereafter the mixture is heated to 120°C under a flow of nitrogen at 28 L/hr (1.0 std. ftVhrN When 120°C is reached, 252 g diluent oil is added, and the mixtures is stripped for 1 hour at a pressure of 2.7 kPa (20 torr) at 120°C for 1 hour and then filtered.

The resulting product is analyzed and contains 1.5% by weight magne- sium and has a Total Base Number (TBN) of 63. Analysis of the product by ID and 2D 1H/¹³C NMR reveals an aldehyde content of 29 mole %, a methylene bridge content of 38 mole %, an ether bridge content of 12 mole %, and a hydroxymethyl content of 21 mole %. Example 2 (Comparative). Example 1 is substantially repeated except that Ca(OH)₂ replaces the

MgO and no catalytic NaOH is employed. After stripping under a nitrogen flow at 150°C and isolation by filtration, the resulting product is analyzed and determined to contain 14 mole % aldehyde functionality.

The material prepared by the above process can be further treated by boration or by overbasing. Borated compositions are prepared by reaction of the above-described saligenin derivative one or more boron compounds. Suitable boron compounds include boric acid, borate esters, and alkali or mixed alkali metal and alkaline earth metal borates. These metal borates are generally a hydrated particulate metal borate and they, as well as the other borating agents, are known in the art and are available commercially. Typically the saligenin derivative is heated with boric acid at 50-100°C or 100-150°C.

Example 3 (comparative - prepared without strong base) To a 5-L, 4-necked round bottom flask equipped with stirrer, stopper, thermowell, and reflux condenser, the following are charged: 670 g diluent oil (mineral oil), 1000 g dodecyl phenol, and 40 g water. The mixture is heated to 35°C with stirring (350 r.p.m.). When 35°C is attained, 170 g of paraformaldehyde (90%) are added to the mixture and stirring is continued. After 5 minutes, 5 g of MgO and 102 g of additional diluent oil are added. The mixture is heated to 79°C and held at temperature for 30 minutes. A second increment of 58 g MgO is added and the batch further heated and maintained at 95-100°C for 1 hour. After the 1 hour hold, 252 g diluent oil is added. Thereafter the mixture is heated to 150°C under a flow of nitrogen at 28 L/hr (1.0 std. ft³/hr.), held 1 hour, and then filtered.

The resulting product is analyzed and contains 0.4% by weight magne- sium and has a Total Base Number (TBN) of 22. Analysis of the product by ID and 2D 'H/^C NMR reveals an aldehyde content of 6 mole %, a methylene bridge content of 88 mole %, an ether bridge content of 2 mole %, and a hy- droxymethyl content of 4 mole %. Example 4.

To a 5-L, 4-necked round bottom flask equipped with stirrer, stopper, thermowell, and reflux condenser, the following are charged: 1466 g toluene, 1600 g dodecyl phenol, and a solution of 10 g of a 50/50 mixture of NaOH and water. The mixture is heated to 35°C with stirring (350 r.p.m.). When 35°C is attained, 403 g of paraformaldehyde (90%) are added to the mixture and stirring is continued. After 5 minutes, 8 g of MgO is added. The mixture is heated to 79°C and held at temperature for 30 minutes. A second increment of 93 g MgO is added and the batch is heated to 80°C for 1 hour. Thereafter the mixture is heated to 80°C and held for lhr and thereafter the mixture is filtered.

The resulting product is analyzed and contains 2.4% by weight magne- sium and has a Total Base Number (TBN) of 99. Analysis of the product by ID and 2D 1H/¹³C NMR reveals an aldehyde content of 16 mole %, a methylene bridge content of 7 mole %, an ether bridge content of 9 mole %, and a hydroxymethyl content of 68 mole %. Example 5. Borated material. To a 5-L, 4-necked round bottom flask equipped with stirrer, stopper, thermowell, and reflux condenser, the following are charged: 356 g of the product of Example 1, 100 g toluene, and 11.4 g H₃BO₃. The mixture is heated to 80°C with stirring at 350 r.p.m. and maintained at temperature for 30 minutes. Thereafter the mixture is heated to 100°C and held at temperature for 2-4 hours. The mixture is stripped of volatiles for 1 hour at a pressure of 2.7 kPa (20 torr) at 120°C and then filtered.

The resulting product is analyzed and contains 1.4% by weight magnesium, 0.3% by weight boron, and has a Total Base Number (TBN) of 63. Analysis of the product by ID and 2D ^!H ¹³C NMR reveals an aldehyde con- tent of 27 mole %, a methylene bridge content of 38 mole %, an ether bridge content of 13 mole %, and a hydroxymethyl content of 22 mole %.

The material can also be overbased. Overbased salts of organic acids are widely known to those of skill in the art and generally include metal salts wherein the amount of metal present in them exceeds the stoichiometric amount. Such salts are said to have conversion levels in excess of 100% (i.e., they comprise more than 100% of the theoretical amount of metal needed to convert the acid to its "normal" or "neutral" salt). They are commonly referred to as overbased, hyperbased or superbased salts and are usually salts of organic sulfur acids, organic phosphorus acids, carboxylic acids, phenols or mixtures of two or more of any of these. As a skilled worker would realize, mixtures of such overbased salts can also be used.

The terminology "metal ratio" is used in the prior art and herein to designate the ratio of the total chemical equivalents of the metal in the over- based salt to the chemical equivalents of the metal in the salt which would be expected to result in the reaction between the organic acid to be overbased and the basically reacting metal compound according to the known chemical reactivity and stoichiometry of the two reactants. Thus, in a normal or neutral salt the metal ratio is one and, in an overbased salt, the metal ratio is greater than one. The overbased salts used as component (A) in this invention usually have metal ratios of at least 1.2: 1 or 1.4: 1. Often they have ratios of at least 2: 1 or 4: 1. Usually they have metal ratios not exceeding 20: 1. Typically, salts having ratios of 1.5: 1 to 15: 1 are used.

When the material of the present invention is overbased, the stoichi- ometrically excess metal can be magnesium or it can be another metal or a mixture of cations. The basically reacting metal compounds used to make these overbased salts are usually an alkali or alkaline earth metal compound (i.e., the Group IA, IIA, and IIB metals excluding francium and radium and typically excluding rubidium, cesium and beryllium), although other basically reacting metal compounds can be used. Compounds of Ca, Ba, Mg, Na and Li, such as their hydroxides and alkoxides of lower alkanols are usually used as basic metal compounds in preparing these overbased salts but others can be used as shown by the prior art referred to herein. Overbased salts containing a mixture of ions of two or more of these metals or other cations, including mixtures of alkaline earth metals such as Mg and Ca, can be used in the present invention.

Overbased materials are generally prepared by reacting an acidic mate- rial (typically an inorganic acid or lower carboxylic acid, preferably carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc.) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter. The acidic organic compound will, in the present instance, be the above-described saligenin derivative. The acidic material used in preparing the overbased material can be a liquid such as formic acid, acetic acid, nitric acid, or sulfuric acid. Acetic acid is particularly useful. Gaseous acidic materials can also be used, such as HC1, SO₂, SO₃, CO₂, or H₂S, preferably CO₂ or mixtures thereof, e.g., mixtures of CO₂ and acetic acid. The acidic material, which is preferably an acidic gas, is reacted with the mixture under conditions to react, normally, with the majority of, preferably 80-95% or 85-90% of, the stoichiometric excess of the metal base. Strongly acidic materials, however, would normally be used in an amount less than an equivalent of the phenol, while weakly acidic materials such as CO₂ can be used in excess.

A promoter is a chemical employed to facilitate the incorporation of metal into the basic metal compositions. The promoters are diverse and are well known in the art. A discussion of suitable promoters is found in U.S. Patents 2,777,874, 2,695,910, and 2,616,904. These include the alcoholic and phenolic promoters, which are preferred. The alcoholic promoters include the alkanols of one to twelve carbon atoms such as methanol, ethanol, amyl alcohol, octanol, isopropanol, and mixtures of these. 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 nonylphenols. Mixtures of various promoters are sometimes used.

Patents specifically describing techniques for making basic salts of acidic organic compounds generally include U.S. Patents 2,501,731; 2,616,905; 2,616,911 ; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and 3,629,109.

Example 6. Mg saligenin derivative overbased with Ca. Into a 2 L four-necked flask equipped with stirrer, thermowell, reflux condenser, and a subsurface tube, is charged 1000 g of the product of Example 1 (Mg saligenin derivative in diluent oil), 50 g of a mixture of isobutyl and amyl alcohols, 100 g of methanol, and 74 g of Ca(OH)₂. A solution of 1 g acetic acid in 4 g water is added to the flask and the contents are held, with stirring, at 44°C for 30 minutes. Carbon dioxide is blown through the mixture for 1 hour or longer, at 14 L/hr (0.5 std. ft³/hr.) until a direct base number of 15 is obtained. The mixture is heated to 120°C under a nitrogen flow of 28 L/hr (1.0 std. ft³/hr.) for 1 hour, to strip volatiles. The resulting mixture is filtered and determined to have a TBN of 142 and to contain 3% Ca and 1.4 % Mg by weight. NMR analysis reveals 30% aldehyde functionality, 39% methylene coupling, 17% ether coupling, and 14% hydroxymethyl functionality. Example 7.

Into a 3 L four-necked flask equipped as in Example 6 is charged 100 g of the product of Example 1, 50 g of a mixture of isobutyl and amyl alcohols, and 111 g Ca(OH)₂. The mixture is heated to 50°C and a solution of 159 g of stearic acid and 150 g diluent oil are added. The mixture is heated to 70°C and maintained at temperature for 30 minutes, then cooled to 60°C. To the mixture is added 100 g of methanol and 10 g acetic acid. Carbon dioxide is blown through the mixture for 1 hour or longer at 28 L/hr (1.0 std. ft³/hr.) to a direct base number of 15. A second increment of Ca(OH)₂, 111 g, is added and carbon dioxide is similarly blown through the mixture to a direct base number of 15. The mixture is stripped at 120°C under a nitrogen flow of 28 L/hr (1.0 std. ft /hr.) and maintained at temperature for 1 hour. The product is filtered and exhibits a TBN of 234, containing 7% Ca and 1% Mg. Analysis reveals 31% aldehyde functionality, 39% methylene coupling, 18% ether coupling, and 12 % hydroxymethyl functionality.

Example 8. Mg overbased saligenin derivative. Into a 2-liter, four-necked flask equipped with stirrer, thermowell, reflux con- denser, and subsurface tube, is charged 1000 g of the product of example 1, 50 g of a mixture of isobutyl and amyl alcohols, and 63 g MgO. The mixture is heated, with stirring, to 50°C. A solution of 130 g of stearic acid and 100 g of dil oil is added. The mixture is heated to 70°C and held at this temperature for 3 hours. The mixture was cooled to 60°C. To the mixture, 100 g of methanol and 7 g acetic acid are added. Carbon dioxide is blown through the mixture for over 3 hours at 28 L/hr (0.5 std. ft³/hr) until a direct base number of less than 5 is obtained for the mixture. The mixture is stripped to 120°C under a carbon dioxide flow of 28 L/hr (0.5 std. ft³/hr) and held at this temperature for 1 hour under nitrogen flow at 14 L/hr (0.5 std. ft³/hr.). The product is filtered and determined to have a TBN of 130 and to contain 2.8 weight % magnesium. Analysis reveals 32% aldehyde functionality, 41% methylene coupling, 12% ether coupling, and 15% hydroxymethyl functionality.

The overbased material can also be borated by reaction with a borating agent in a known manner, as briefly described above. The Mg saligenin derivative can be incorporated into the lubricant along with other components in any order. It can be blended along with the other components or it can be added afterwards as a top-treatment.

In another embodiment, a lubricating oil composition containing the magnesium saligenin derivative may contain one or more additional components including, typically, at least one of the following:

(B) a metal overbased composition (other than the overbased material described above)

(C) a dispersant,

(D) a metal salt represented by the formula,

and

(E) an antioxidant. (B) The (Other) Metal Overbased Composition

Overbased compositions are well known, and the general process for preparing overbased compositions has been described in connection with the preparation of overbased Mg saligenin derivatives, above. The optional other overbased compositions can be prepared based on a variety of other well known organic acidic materials including sulfonic acids, carboxylic acids (including substituted salicylic acids), phenols, phosphonic acids, and mixtures of any two or more of these. These materials and methods for overbasing of them are well known from numerous U.S. Patents including those mentioned above in connection with the overbasing of the saligenin derivative and need not be further described in detail.

Preferred overbased materials include overbased phenates derived from the reaction of an alkylated phenol, preferably wherein the alkyl group has at least 6 aliphatic carbon atoms. The phenate is optionally reacted with an aldehyde such as formaldehyde or acetaldehyde, or an aldehyde-containing com- pound such as glyoxylic acid, or with a sulfurization agent, or mixtures thereof, to provide a bridged or linked structure. Other preferred overbased materials include metal overbased sulfonates derived from an alkylated aryl sulfonic acid wherein the alkyl group has at least 15 aliphatic carbon atoms.

Other preferred overbased materials include metal overbased carboxy- lates derived from fatty acids having at least 8 aliphatic carbon atoms.

The preferred overbased materials may contain any of the metal components described above and mixtures thereof, but preferably an alkali metal or alkaline earth metal, more preferably calcium, magnesium, lithium or sodium. The other, optional overbased material can also be borated (as can the overbased saligenin derivative) by treatment with a borating agent such as boric acid. Typical conditions include heating the basic metal salt with boric acid at 50 to 100°C or 100 to 150°C, the number of equivalents of boric acid being roughly equal to or less than the number of equivalents of metal in the salt. U.S. Patent No. 3,929,650 discloses borated complexes and their prepa- ration.

(O The Dispersant

Dispersants are well known in the field of lubricants and include primarily what are sometimes referred to as "ashless" dispersants because (prior to mixing in a lubricating composition) they do not contain ash-forming metals and they do not normally contribute any ash forming metals when added to a lubricant. Dispersants are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain.

One class of dispersant is Mannich bases. These are materials which are formed by the condensation of a higher molecular weight, alkyl substituted phenol, an alkylene polyamine, and an aldehyde such as formaldehyde. Such materials may have the general structure

(including a variety of isomers and the like) and are described in more detail in U.S. Patent 3,634,515. Another class of dispersant is high molecular weight esters. These materials are similar to the above-described succinimides except that they may be seen as having been prepared by reaction of a hydrocarbyl acylating agent and a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol. Such materials are described in more detail in U.S. Patent 3,381,022.

Other dispersants include polymeric dispersant additives, which are generally hydrocarbon-based polymers which contain polar functionality to impart dispersancy characteristics to the polymer.

A preferred class of dispersants is the carboxylic dispersants. Carboxylic dispersants include succinic-based dispersants, which are the reaction product of a hydrocarbyl substituted succinic acylating agent with an organic hydroxy compound or, preferably, an amine containing at least one hydrogen attached to a nitrogen atom, or a mixture of said hydroxy compound and amine. The term "succinic acylating agent" refers to a hydrocarbon-substituted succinic acid or succinic acid-producing compound. Such materials typically include hydrocarbyl-substituted succinic acids, anhydrides, esters (including half esters) and halides.

Succinic based dispersants have a wide variety of chemical structures including typically structures such as

In the above structure, each R is independently a hydrocarbyl group, preferably a polyolefin-derived group having an Mn of 500 or 700 to 10,000, where Mn is number average molecular weight. Typically the hydrocarbyl group is an alkyl group, frequently a polyisobutyl group with Mn of 500 or 700 to 5000, preferably 1500 or 2000 to 5000. Alternatively expressed, the R¹ groups can contain 40 to 500 carbon atoms and preferably 50 to 300 carbon atoms, preferably aliphatic carbon atoms. The R² are alkenyl groups, commonly ethylenyl (C₂H₄) groups. Such molecules are commonly derived from reaction of an alkenyl acylating agent with a polyamine, and a wide variety of linkages between the two moieties is possible beside the simple imide structure shown above, including a variety of amides and quaternary ammonium salts. Succinimide dispersants are more fully described in U.S. Patent 4,234,435. The polyalkenes from which the substituent groups are derived are typically homopolymers and interpolymers of polymerizable olefin monomers of 2 to 16 carbon atoms; usually 2 to 6 carbon atoms.

The olefin monomers from which the polyalkenes are derived are polymerizable olefin monomers characterized by the presence of one or more ethylenically unsaturated groups (i.e., >C=C<); that is, they are mono-olefinic monomers such as ethylene, propylene, 1-butene, isobutene, and 1-octene or polyolefinic monomers (usually diolefinic monomers) such as 1,3-butadiene, and isoprene. These olefin monomers are usually polymerizable terminal olefins; that is, olefins characterized by the presence in their structure of the group >C=CH₂. Relatively small amounts of non-hydrocarbon substituents can be included in the polyolefin, provided that such substituents do not substantially interfere with formation of the substituted succinic acid acylating agents.

Each R¹ group may contain one or more reactive groups, e.g., succinic groups, thus being represented (prior to reaction with the amine) by structures such as

in which y represents the number of such succinic groups attached to the R¹ group. In one type of dispersant, y = 1. In another type of dispersant, y is greater than 1, preferably greater than 1.3 or greater than 1.4; and most preferably y is equal to or greater than 1.5. Preferably y is 1.4 to 3.5, especially is 1.5 to 3.5 and most especially 1.5 to 2.5. Fractional values of y, of course, can arise because different specific R¹ chains may be reacted with different numbers of succinic groups. The amines which are reacted with the succinic acylating agents to form the carboxylic dispersant composition can be monoamines or polyamines. In either case they will be characterized by formula R⁴R⁵NH wherein R⁴ and R⁵ are each independently hydrogen, or hydrocarbon, amino-substituted hydrocarbon, hydroxy-substituted hydrocarbon, alkoxy-substituted hydrocarbon, amino, carbamyl, thiocarbamyl, guanyl, and acylimidoyl groups provided that only one of R⁴ and R⁵ is hydrogen. In all cases, therefore, they will be characterized by the presence within their structure of at least one H-N< group. Therefore, they have at least one primary (i.e., H₂N-) or secondary amino (i.e., H-N<) group. Examples of monoamines include ethylamine, diethyl amine, n- butylamine, di-n-butylamine, allylamine, isobutylamine, cocoamine, stearyla- mine, laurylamine, methyllaurylamine, oleyl-amine, N-methyl-octylamine, dodecylamine, and octadecylamine.

The polyamines from which (C) is derived include principally alkylene amines conforming, for the most part, to the formula

A — N-(alkylene-N)_t — H

A A wherein t is an integer preferably less than 10, A is a hydrogen group or a hydrocarbyl group preferably having up to 30 carbon atoms, and the alkylene group is preferably an alkylene group having less than 8 carbon atoms. The alkylene amines include principally methylene amines, ethylene amines, hexy- lene amines, heptylene amines, octylene amines, other polymethylene amines. They are exemplified specifically by: ethylene diamine, triethylene tetramine, propylene diamine, decamethylene diamine, octamethylene diamine, di(heptamethylene) triamine, tripropylene tetramine, tetraethylene pentamine, trimethylene diamine, pentaethylene hexamine, di(-trimethylene) triamine. Higher homologues such as are obtained by condensing two or more of the above-illustrated alkylene amines likewise are useful. Tetraethylene pent- amine is particularly useful.

The ethylene amines, also referred to as polyethylene polyamines, are especially useful. They are described in some detail under the heading "Ethylene Amines" in Encyclopedia of Chemical Technology, Kirk and Othmer, Vol. 5, pp. 898-905, Interscience Publishers, New York (1950). Hydroxyalkyl-substituted alkylene amines, i.e., alkylene amines having one or more hydroxyalkyl substituents on the nitrogen atoms, likewise are useful. Examples of such amines include N-(2-hydroxyethyl)ethylene diamine, N,N'-bis(2-hydroxy-ethyl)-ethylene diamine, l-(2-hydroxyethyl)piperazine, monohydroxypropyl)-piperazine, di-hydroxypropy-substituted tetraethylene pentamine, N-(3-hydroxypropyl)-tetra-methylene diamine, and 2-heptadecyl-l- (2-hydroxyethyl)-imidazoline.

Higher homologues, such as are obtained by condensation of the above- illustrated alkylene amines or hydroxy alkyl-substituted alkylene amines through amino radicals or through hydroxy radicals, are likewise useful. The carboxylic dispersant composition (C), obtained by reaction of the succinic acid-producing compounds and the amines described above, may be amine salts, amides, imides, imidazolines as well as mixtures thereof. To prepare the carboxylic dispersant composition (C), one or more of the succinic acid-producing compounds and one or more of the amines are heated, optionally in the presence of a normally liquid, substantially inert organic liquid solvent/diluent at an elevated temperature, generally in the range of 80°C up to the decomposition point of the mixture or the product; typically 100°C to 300°C.

The succinic acylating agent and the amine (or organic hydroxy compound, or mixture thereof) are reacted in amounts sufficient to provide at least one-half equivalent, per equivalent of acid-producing compound, of the amine (or hydroxy compound, as the case may be). Generally, the maximum amount of amine present will be about 2 moles of amine per equivalent of succinic acylating agent. For the purposes of this invention, an equivalent of the amine is that amount of the amine corresponding to the total weight of amine divided by the total number of nitrogen atoms present. The number of equivalents of succinic acid-producing compound will vary with the number of succinic groups present therein, and generally, there are two equivalents of acylating reagent for each succinic group in the acylating reagents. Additional details and examples of the procedures for preparing the nitrogen-containing compositions of the present invention by reaction of succinic acid-producing com- pounds and amines are included in, for example, U.S. Pat. Nos. 3,172,892; 3,219,666; 3,272,746; and 4,234,435.

The dispersants may be borated in much the same way as the saligenin derivative or the other overbased material, described above. The dispersants may also be treated by reaction with maleic anhydride as described in PCT application US99/23940 filed 13 October 1999.

(C) The Metal Salt of a Phosphorus Acid

Metal salts of the formula

wherein R and R are independently hydrocarbyl groups containing 3 to 30 carbon atoms are readily obtainable by the reaction of phosphorus pentasulfide (P₂S₃) and an alcohol or phenol to form an O,O-dihydrocarbyl phosphorodithioic acid corre¬

The reaction involves mixing at a temperature of 20°C to 200°C, four moles of an alcohol or a phenol with one mole of phosphorus pentasulfide. Hydrogen sulfide is liberated in this reaction. The acid is then reacted with a basic metal compound to form the salt. The metal M, having a valence n, generally is aluminum, lead, tin, manganese, cobalt, nickel, zinc, or copper, and most preferably zinc. The basic metal compound is thus preferably zinc oxide, and the resulting metal compound is represented by the formula

The R⁸ and R⁹ groups are independently hydrocarbyl groups that are preferably free from acetylenic and usually also from ethylenic unsaturation. They are typically alkyl, cycloalkyl, aralkyl or alkaryl group and have 3 to 20 carbon atoms, preferably 3 to 16 carbon atoms and most preferably up to 13 carbon atoms, e.g., 3 to 12 carbon atoms. The alcohol which reacts to provide the R⁸ and R⁹ groups can be a mixture of a secondary alcohol and a primary alcohol, for instance, preferably a mixture of isopropanol and 4-methyl-2-pentanol.

Such materials are often referred to as zinc dialkyldithiophosphates or simply zinc dithiophosphates. They are well known and readily available to those skilled in the art of lubricant formulation.

The amount of the metal salt of a phosphorus acid in a completely formulated lubricant, if present, will typically be 0.1 to 4 percent by weight, preferably 0.5 to 2 percent by weight, and more preferably 0.75 to 1.25 percent by weight. Its concentration in a concentrate will be correspondingly increased, to, e.g., 5 to 20 weight percent. (E) The Antioxidant

In a further embodiment, the lubricating oil composition may also contain an antioxidant. Antioxidants for use in lubricant compositions are well known and include a variety of chemical types including phenate sulfides, phosphosulfurized terpenes, sulfurized esters, aromatic amines, and hindered phenols.

Aromatic amine are typically of the formula

wherein R⁵ is a phenyl group or a phenyl group substituted by R⁷, and R and R⁷ are independently a hydrogen or an alkyl group containing 1 to 24 carbon atoms. Preferably R is a phenyl group substituted by R and R and R are alkyl groups containing from 4 to 20 carbon atoms. In one embodiment the antioxidant can be an alkylated diphenylamine such as nonylated diphenyla- mine of the formula

Hindered phenol antixoidants are typically alkyl phenols of the formula

wherein R > 4 i •s an alkyl group containing 1 up to 24 carbon atoms and a is an integer of 1 to 5. Preferably R⁴ contains 4 to 18 carbon atoms and most preferably from 4 to 12 carbon atoms. R⁴ may be either straight chained or branched chained; branched chained is generally preferred. The preferred value for a is an 1 to 4 and most preferred 1 to 3 or, particularly, 2. Preferably the phenol is a butyl substituted phenol containing 2 or 3 t-butyl groups. When a is 2, the t-butyl groups occupy the 2,6-position, that is, the phenol is sterically hindered:

A particularly preferred antioxidant is a hindered, ester-substituted phenol such as one represented by the formula

t-alkyl and more preferably

wherein R is a straight chain or branched chain alkyl group containing 2 to 22 carbon atoms, preferably 2 to 8, 2 to 6, or 4 to 8 carbon atoms and more pref- erably 4 or 8 carbon atoms. R³ is desirably a 2-ethylhexyl group or an n-butyl group.

Hindered, ester-substituted phenols can be prepared by heating a 2,6- dialkylphenol with an acrylate ester under base catalysis conditions, such as aqueous KOH. Example 9. To a 5-L round-bottomed 4-necked flask, equipped with a mechanical stirrer, thermal probe, and reflux condenser equipped for distillate removal, is charged 2619 g 2,6-di-t-butylphenol and 17.7 g potassium hydrox- ide (technical grade). The reaction mixture is heated to 135°C over 35 minutes and maintained at temperature for 2 hours, removing 9.7 g aqueous distillate. To the reaction mixture is charged 1466 g butyl acrylate dropwise over the course of 90 minutes. The temperature is maintained at 135°C for up to 2 hours, or until analysis by infrared indicates no further change (by observing peaks at 727 and 768 cm^"1). To the mixture is charged 103 g of a MgSiO₄ adsorbent, 17 g filter aid and stirring is continued for 2 hours, while removing 7.1 g distillate. The mixture is filtered through additional filter aid.

The compositions of the present invention may also include, or exclude, other components which are commonly found in lubricating compositions. For instance, corrosion inhibitors, extreme pressure agents, and anti-wear agents include but are not limited to chlorinated aliphatic hydrocarbons; boron-containing compounds including borate esters; and molybdenum compounds. Viscosity improvers include but are not limited to polyisobutenes, polymethyacrylate acid esters, polyacrylate acid esters, diene polymers, polyalkyl styrenes, alkenyl aryl conjugated diene copolymers, polyolefins and multifunctional viscosity improvers, including dispersant viscosity modifiers (which impart both dispersancy and viscosity improvement). Pour point depressants are a particularly useful type of additive, often included in the lubri- eating oils described herein usually comprising substances such as polymethacrylates, styrene-based polymers, crosslinked alkyl phenols, or alkyl naphthalenes,. 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 which may be used in combination with the present invention are described in greater detail in U.S. Patent 4,582,618 (column 14, line 52 through column 17, line 16, inclusive) The effectiveness of the magnesium saligenin derivatives of the present invention, as opposed to known calcium saligenin derivatives, is reported in the following sets of differing formulations. The Ca saligenin derivative is prepared substantially as in Example 2 and is determined to contain 6 mole % aldehyde functionality content. The Mg saligenin derivative is prepared substantially as in Example 1 and is analyzed to have an aldehyde content of 31 mole %, a methylene bridge content of 31 mole %, an ether bridge content of 13 mole %, and a hydroxymethyl content of 25 mole %. In each of the pairs of examples within a formulation below, the composition remains constant except for the replacement of the Ca saligenin derivative with the Mg saligenin derivative. All amounts are presented inclu- sive of the diluent oil normally found in each component, unless otherwise noted. Other conventional additives which do not vary from one formulation to the next (dispersant, inhibitor, anti-foam and anti-wear agents) are not specifically listed.

The Examples are subjected to a series of 4 tests. The first is a copper corrosion test which involves immersing a copper coupon into a specimen of oil, heating the sample to 135°C, and blowing air through the heated sample for a defined number of hours. Lesser amounts of Cu detected in the samples after the test are better.

The Volkswagen seal test involves immersing a number of specimens of cured Viton™ elastomer seal material in a sample of fluid to be tested and holding the samples at 150°C for three 94-hour periods, replacing the test oil after the second 94 hour period. In this test the tension at break of the Viton™ seal after exposure (at 200 mm/min) is preferably at least 8 N/mm² and the elongation at break is preferably at least 160%. The seal preferably exhibits little or no cracking when tested by maintaining the specimen stretched to 100% elongation for 30 minutes.

The RBOT test is ASTM D-2272. The results are reported as time, in minutes, for oxygen pressure to decrease by 175 kPa (25.4 psi) from maximum pressure. Samples with higher oxidative induction time are superior, illustrat- ing improved oxidative stability.

The Hot Tube Thermal Stability Test simulates deposit-forming tendencies in crankcase lubricants. A sample of lubricant is forced continuously at 285°C through a small glass tube for 20 hours. At the conclusion of the test the deposits on the tube are visually evaluated for deposits. Higher ratings indicate less deposits (greater thermal stability).

n.d. = not determined a. Viscosity modifier for this formulation is supplied without diluent oil.

While the invention has been explained in relation 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 disclosure. 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.

Each of the documents referred to above is incorporated herein by reference. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word "about." Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical com- ponent is presented exclusive of any solvent or diluent oil which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. As used herein, the expression "consisting essentially of" permits the inclusion of substances which do not materially affect the basic and novel characteristics of the composition under consideration.

Claims

What is claimed is:

1. A composition comprising (A) a saligenin derivative represented by the formula

wherein each X independently is -CHO, or -CH₂OH, each Y independently is -CH₂- or -CH₂OCH -, and wherein such -CHO groups comprise at least 10 mole percent of the X and Y groups; each M is independently hydrogen, ammonium, or a valence of a metal ion; each R¹ is independently a hydrocarbyl group containing 1 to 60 carbon atoms; m is 0 to 10; and each p is independently 0, 1, 2, or 3; provided that at- least one aromatic ring contains an R¹ substituent and that the total number of carbon atoms in all R¹ groups is at least 7; further provided that if m is 1 or greater, then one of the X groups can be -H.

2. The composition of claim 1 wherein each M is independently Mg or H and the percentage of phenolic OH groups which are neutralized by Mg is 10 to 100%.

3. The composition of claim 1 wherein the saligenin derivative is an overbased salt.

4. The composition of claim 3 wherein the saligenin derivative is an overbased magnesium or calcium salt or an overbased mixture of magnesium and calcium salts.

5. The composition of any of the preceding claims wherein the -CHO groups comprise 20 to 60 mole percent of the X and Y groups.

6. The composition of any of the preceding claims wherein when X is at least in part -CH₂OH and such -CH₂OH groups comprise 10 to 50 mole per- cent of the X and Y groups.

7. The composition of any of the preceding claims wherein when Y is at least in part -CH₂-and such -CH₂- groups comprise 25 to 55 mole percent of the X and Y groups.

8. The composition of any of the preceding claims wherein when Y is at least in part -CH₂OCH₂- and such -CH₂OCH₂- groups comprise 5 to 20 mole percent of the X and Y groups.

9. The composition of any of the preceding claims wherein (A) is treated with a borating agent.

10. A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount of the saligenin derivative (A) of any of the preceding claims.

1 1. The composition of any of the preceding claims further comprising an antioxidant represented by the formula

t-alkyl

wherein R³ is a straight chain or branched chain alkyl group containing 2 to 22 carbon atoms.

12. A process for preparing a saligenin derivative represented by the formula

wherein each X independently is -CHO or -CH₂OH, each Y independently is -CH₂- or -CH₂OCH₂-; each R¹ is independently a hydrocarbyl group containing 1 to 60 carbon atoms; each n is independently 0 or 1, the average value of n in the composition being 0.1 to 0.5; provided that when n is 0, the Mg is replaced by H; m is 0 to 10; and each p is independently 0, 1, 2, or 3; provided that at least one aromatic ring contains an R¹ substituent and that the total number of carbon atoms in all R¹ groups is at least 7; further provided that if m is 1 or greater, then one of the X groups can be

-H; said process comprising: combining (a) a phenol substituted by said R¹ group with (b) formaldehyde or a source of formaldehyde, and (c) and magnesium oxide or magnesium hydroxide, under reactive conditions in the presence of a catalytic amount of a strong base; wherein the equivalent ratio of the substituted phenol to formaldehyde or source thereof is 1: 1 to 1:4; whereby said saligenin derivative is formed such that X is at least in part -CHO and such -CHO groups comprise at least 10% of the X and Y groups.

13. The process of claim 12 wherein the strong base is sodium hydroxide or potassium hydroxide and the reaction mixture is heated to a final temperature of 100 to 150°C.

14. A process for preparing an overbased saligenin derivative, comprising adding to the product of claim 12 or 13 an excess of a basic metal compound and adding thereto a gaseous acidic material under conditions to react with the majority of the stoichiometric excess of the metal base.