Overbased metal salts, their preparation and use

Abstract: An overbased metal salt of a hydrocarbyl-substituted sulphurised or non sulphurised phenol, a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin wherein the metal moiety comprises a first metallic component which is at least one alkaline earth metal and a second metallic component which is at least one of either (i) at least one alkali metal or (ii) at least one metal selected from Groups IIIa, IVa, Va, VIa, VIIa and VIII of either the first or the second transition series of the Periodic Table of the Elements, the weight ratio of the first metal component to the second metal component being in the range from 1000:1 to 2:1.

Description: The present invention relates in general to overbased alkaline earth metal salts of non-sulphurised hydrocarbyl-substituted phenols, calixarenes and linear phenol/formaldehyde resins, their preparation and their use as additives in lubricating oils and fuels. In the internal combustion engine, by-products from the combustion chamber often blow by the piston and admix with the lubricating oil. Many of these by-products form acidic materials within the lubricating oil. This is particularly marked in diesel engines operating on low-grade fuels of high sulphur content wherein corrosive acids are produced by combustion. The acids thereby incorporated in the lubricating oil can include sulphur acids produced by oxidation of sulphur, hydrohalic acids derived from halogen lead scavengers in the fuel and nitrogen acids produced by the oxidation of atmospheric nitrogen within the combustion chamber. Such acids cause deposition of sludge and corrosion of the bearings and engine parts leading to rapid wear and early breakdown of the engine. One class of compounds generally employed to neutralise the acidic materials and disperse sludge within the lubricating oil are the metal alkyl phenates, wherein the metal is an alkaline earth metal such as calcium, magnesium or barium. Both "normal" and "overbased" alkaline earth metal alkyl phenates have been employed. The term "overbased" is used to describe those alkaline earth metal alkyl phenates in which the ratio of the number of equivalents of the alkaline earth metal moiety to the number of equivalents of the phenol moiety is greater than one, and is usually greater than 1.2 and may be as high as 4.5 or greater. In contrast, the equivalent ratio of alkaline earth metal moiety to phenol moiety in "normal" alkaline earth metal alkyl phenates is one. Thus, the "overbased" material contains greater than 20% in excess of the alkaline earth metal present in the corresponding "normal" material. For this reason "overbased" alkaline earth metal alkyl phenates have a greater capability for neutralising acidic matter than do the corresponding "normal" alkaline earth metal alkyl phenates. Other classes of compounds said to be useful for the same purpose are the overbased metal salts of calixarenes as described, for example, in EP-A-0 450 874 and the overbased metal salts of linear phenol/formaldehyde resins. Whilst the aforesaid compounds perform perfectly adequately as detergents, there remains scope for improvement in other properties. Thus, for example, a desirable objective would be to improve the anti-wear and frictional properties of the overbased alkaline earth metal non-sulphurised hydrocarbyl-substituted phenates. We have found that these and other properties of the aforesaid detergents can be improved by incorporating into them, in addition to the alkaline earth metal, at least one further metal, in particular lithium or potassium in relatively small amounts. The use of mixtures of an alkaline earth metal and another metal in lubricating oil compositions is known from, for example WO-A-93/03121, WO-A-93/06195, US-A-4 767 551; US-A-4 664 822; US-A-4 252 698; US-A-3 793 201; US-A-4 832 857; US-A-5 030 687; EP-A-0 573 231 and US-A-4 021 419. WO-A-93/03121 describes overbased metal salts of hydrocarbyl-substituted phenols wherein the metal moiety is an alkali or alkaline earth metal, copper or zinc, preferably sodium, potassium, calcium or magnesium and their use in combination with other components for improving the wet filterability of lubricants and functional fluids. WO-A-93/06195 discloses the use of ultrasound in the preparation of oil-soluble sulphonates, phenates, sulphurised phenates, thiophosphonates, salicylates and naphthenates and other carboxylates of a metal, particularly the alkali or alkaline earth metals or magnesium, for example sodium, lithium, calcium, barium and magnesium. The most commonly used metals are said to be calcium and magnesium, mixtures of calcium and magnesium, and mixtures of calcium and/or magnesium with sodium. US-A-4 767 551 discloses lubricant compositions comprising inter alia 0.1-5wt% of a dispersant/detergent, antioxidant and corrosion inhibitor additive comprising an overbased copper/metal sulphonate, phenate and/or salicylate in which the metal is magnesium, calcium or sodium. US-A-4 664 822 discloses metal detergent compositions similar to those described in US-A-4 767 551. US-A-4 252 698 discloses an additive for environmentally acceptable stabilised vinyl chloride polymer compositions comprising inter alia at least one overbased metal phenolate or sulphonate of lithium, sodium, magnesium, calcium, strontium and/or barium. An example describes the synthesis of overbased sodium carbonate-barium nonylphenolate. US-A-3,793 201 discloses an oil-soluble composition comprising inter alia (B) an oil-soluble basic magnesium salt of an organic acid and (C) an oil-soluble polyvalent metal salt of a bridged phenol, the amount of (B) and (C) being such that the equivalent ratio of metal contributed to the composition by (B) to that contributed by (C) is 150-30:1. The metal cations of the salts of the bridged phenols may be an alkali or alkaline earth metal cation or a zinc, cadmium, lead, iron, nickel, cobalt, copper, chromium or tin cation or mixtures of these. US-A-4 832 857 describes the incorporation of molybdenum into overbased alkaline earth metal and alkali metal sulfonates, phenates and salicylates by post-addition of molybdenum into a previously prepared overbased composition. US-A-5 030 687 describes the preparation of a mixture of sulphurised, overbased alkylphenate and allcylsalicylate salts of alkali and alkaline earth metals. EP-A-0 573 231 describes lubricating oil compositions comprising a friction-reducing amount of an additive comprising (A) a triglyceride-containing animal or vegetable oil and (B) a metal overbased composition which may contain a mixture of alkali and alkaline earth metals. Finally, US-A-4 021 419 describes overbased metal salts of sulphurised phenol/formaldehyde compositions. None of the aforesaid prior art specifically describes the incorporation of lithium or potassium into overbased alkaline earth metal detergents as described below in amounts which are small relative to the amount of alkaline earth metal for the purpose of improving the detergent's anti-wear and frictional properties. Accordingly, the present invention provides an overbased metal salt of a hydrocarbyl-substituted non-sulphurised phenol, a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin wherein the metal moiety comprises a first metallic component which is at least one alkaline earth metal and a second metallic component which is at least one of lithium and potassium, the weight ratio of the first metal component to the second metal component being in the range from 1000:1 to 2:1. The weight ratio of the first metallic component to the second metallic component is in the range from 1000:1 to 2:1, typically from 500:1 to 2:1, for example from 150:1 to 2:1. The overbased metal salt is an overbased metal salt of either a hydrocarbyl-substituted non-sulphurised phenol, or a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin. As regards the hydrocarbyl-substituted phenol, the hydrocarbyl substituent is preferably an alkyl group which may be branched or unbranched. Suitable alkyl groups contain from 4 to 50, preferably from 9 to 28, carbon atoms. A particularly suitable alkyl phenol is the C 12 - alkyl phenol obtained by alkylating phenol with propylene tetramer. The hydrocarbyl-substituted phenol may be a mono- or a poly-substituted phenol. A particularly suitable poly-substituted phenol is dinonyl phenol. Overbased metal salts of hydrocarbyl-substituted phenols are generally manufactured and sold as concentrates of the metal salt in a suitable lubricating oil. Where sulphur is present in the overbased metal salt the amount of sulphur may suitably be in the range from 1 to 6, typically from 1 to 3% by weight based on the weight of the concentrate. As regards the calixarene having a substituent hydroxyl group or groups available for reaction with metal base, any suitable calixarene may be employed. This includes both sulphurised and non-sulphurised calixarenes. A preferred calixarene is a sulphur-free calixarene, for example a sulphur-free calixarene as described in EP-A-0450874. Suitable calixarenes may be represented by the formula:- wherein in the formula:- Y is a divalent bridging group; R 3 is a hydrocarbyl or a hetero-substituted hydrocarbyl group; either R 1 is hydroxyl and R 2 and R 4 are independently either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl; or R 2 and R 4 are hydroxyl and R 1 is either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl; and n is an integer in the range from 3 to 12. A preferred calixarene has the formula:- wherein in the formula:- R 2 , R 3 and R 4 are independently either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl; either one of R 7 and R 8 is hydrogen and the other is either hydrogen or hydrocarbyl; n is an integer in the range 4 to 9; and e is one or greater, eg 1, 2, 3 or 4. An example of a suitable calixarene of the formula (II) is p-tert-butyl calix [6,8] arene. Other suitable calixarenes include p-dodecyl calix[6] arene, p-nonyl calix[8] arene and p-nonyl [6,7,8] arene. For further details of suitable calixarenes and their preparation reference may be made to the aforesaid EP-A-0450874. As regards the linear phenol/formaldehyde resin, this may suitably be a resin of the formula:- wherein in the formula (III):- R 1 , R 2 and R 3 independently represent either hydrogen or a hydrocarbyl group; x, y and z each independently represent zero or an integer in the range 1 to 3; and g is an integer in the range from 1 to 20. Preferred resins are those of the formula (III) in which x = y = z = 1; R 1 = R 2 = R 3 = a C 1 to C 24 , preferably a C 1 to C 12 alkyl group; and g is in the range from 2 to 7, preferably 3. Such compounds are well-known in the art and may be prepared by the condensation of the appropriate phenol with formaldehyde. The metal moiety of the overbased metal salt comprises a first metallic component which is an alkaline earth metal and a second metallic component which is at least one of lithium and potassium. As regards the first metallic component, suitably the alkaline earth metal is either calcium, magnesium or barium, preferably calcium. As regards the second metallic component, this is lithium or potassium. The overbased metal salts of the present invention will generally take the form of a solution in an appropriate solvent, which will generally be a lubricating oil. Accordingly, in another aspect the present invention provides a concentrate composition which comprises at least one overbased metal salt of either a hydrocarbyl-substituted non-sulphurised phenol, a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin as hereinbefore described and a solvent therefor, the overbased metal salt comprising from greater than 10 to less than 90% by weight of the composition. The solvent for the overbased metal salt may be any suitable solvent, for example, a hydrocarbon solvent, but in view of the intended use of the salt as a lubricating oil additive it is preferably a lubricating oil. The Total Base Number (TBN) expressed in mg KOH/g of the concentrate may suitably be in the range from 75 to 500, typically in the range from 100 to 450, for example 150 to 400. The overbased metal salt comprises from greater than 10 to less than 90, typically from 15 to 80, for example from 20 to 75% by weight of the composition. A preferred overbased metal salt is a lubricating oil concentrate comprising a metal non-sulphurised alkyl phenate, the concentrate having a TBN of greater than 300 and a viscosity at 100°C of less than 1000 cSt, the metal being either a mixture of calcium and either lithium or potassium in a weight ratio of calcium to either lithium or potassium in the range from 6:1 to 25:1. The presence of potassium or lithium in the overbased phenate more than compensates in terms of antiwear properties for the absence of sulphur, the avoidance of which can be desirable environmentally from the point of view of avoiding the hydrogen sulphide emissions generally associated with the products of sulphurised phenates. In another aspect the present invention provides a process for the production of an overbased metal salt as hereinbefore described which process comprises reacting at elevated temperature component (A) either (i) an alkaline earth metal hydrocarbyl-substituted non-sulphurised phenate, or (ii) an alkaline earth metal salt of a calixarene having a substituent hydroxyl group or groups available for reaction with a metal base, or (iii) an alkaline earth metal salt of a linear phenol/formaldehyde resin, or (iv) the precursors of either (i) (ii) or (iii), component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction, component (C) a solvent comprising either:- (C1) either (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di-(C 2 to C 4 ) glycol, (iii) a tri- (C 2 to C 4 ) glycol or (iv) a mono- or poly-alkylene glycol alkyl ether of the formula:- R 3 (OR 4 ) x OR 5 wherein in the formula (IV) R 3 is a C 1 to C 6 alkyl group, R 4 is an alkylene group, R 5 is hydrogen or a C 1 to C 6 alkyl group and x is an integer in the range from 1 to 6, either alone or in combination with either (C2) a hydrocarbon solvent or (C3) either (i) water, (ii) a C 1 to C 20 monohydric alcohol, (iii) a ketone having up to 20 carbon atoms, (iv) a carboxylic acid ester having up to 10 carbon atoms or (v) an ether having up to 20 carbon atoms, or, (C4) a C 1 to C 4 monohydric alcohol in combination with a hydrocarbon solvent, optional component (D) a lubricating oil, component (E) carbon dioxide added subsequent to the, or each, addition of component (B), component (F) either a basic compound or a salt of at least one of lithium and potassium, optional component (G) sufficient to provide from 2 to 40% by weight based on the weight of the concentrate of at least one compound which is G (i) a carboxylic acid or an acid anhydride, ester or salt thereof, said acid having the formula (V) wherein R 1 is a C 10 to C 24 alkyl or alkenyl group and R 2 is hydrogen, a C 1 to C 4 alkyl group or a CH 2 COOH group, or (G) (ii) a poly-carboxylic acid containing from 36 to 100 carbon atoms or an acid anhydride, ester or salt thereof, optional component (H) a catalyst or promoter for the reaction, the amounts of components (B) and (F) being such as to produce an overbased metal salt wherein the weight ratio of the alkaline earth metal of component (B) to the metal of component (F) is in the range from 1000:1 to 2:1. Component (A) is either (i) an alkaline earth metal hydrocarbyl-substituted non-sulphurised phenate, or (ii) an alkaline earth metal salt of a calixarene having a substituent hydroxyl group or groups available for reaction with a metal base, or (iii) an alkaline earth metal salt of a linear phenol/formaldehyde resin, or (iv) the precursors of either (i), (ii) or (iii). The precursors of (i) are, for example, a hydrocarbyl-substituted phenol, an alkaline earth metal base, and optionally carbon dioxide. It is preferred to employ a pre-formed phenate, calixarate or salt of a phenol/formaldehyde resin. Suitable hydrocarbyl-substituents and alkaline earth metals are discussed hereinbefore in relation to the overbased metal salt. Component (B) is an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction. The alkaline earth metal base may suitable be an oxide or hydroxide, preferably the hydroxide. Preferred alkaline earth metals are calcium, magnesium and barium, of which calcium is more preferred. A calcium base may be added, for example, in the form of quick lime (CaO) or in the form of slaked lime [Ca(OH) 2 ] or as a mixture of the two in any proportions. Slaked lime is preferred. Component (C) is a solvent for the reactants. The solvent (C) may be either (C 1 ) either alone or in combination with either (C 2 ) or (C 3 ), or the solvent (C) may be (C 4 ) in combination with (C 2 ) wherein: (C 1 ) is either (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di- (C 3 or C 4 ) glycol, (iii) a tri-(C 2 to C 4 ) glycol or (iv) a mono- or poly-alkylene glycol alkyl ether of the formula:- R 3 (OR 4 ) x OR 5 wherein in the formula (IV) R 3 is a C 1 to C 6 alkyl group, R 4 is an alkylene group, R 5 is hydrogen or a C 1 to C 6 alkyl group and x is an integer from 1 to 6. Suitable compounds having the formula (IV) include the monomethyl or dimethyl ethers of (a) ethylene glycol, (b) diethylene glycol, (c) triethylene glycol or (d) tetraethylene glycol. A suitable compound is methyl diglycol (CH 3 OCH 2 CH 2 OCH 2 CH 2 OH). Mixtures of glycol ethers of formula (IV) and glycols may also be employed. The polyhydric alcohol may suitably be either a dihydric alcohol, for example ethylene glycol or propylene glycol, or a trihydric alcohol, for example glycerol. The di- (C 2 to C 4 ) glycol may suitable be dipropylene glycol, the tri- (C 2 to C 4 ) glycol may suitable be triethylene glycol. Preferably the component (C 1 ) is either ethylene glycol or methyl diglycol. (C 2 ) is a hydrocarbon solvent which may be aliphatic or aromatic. Examples of suitable hydrocarbons include toluene, xylene, naphtha and aliphatic paraffins, for example hexane, and cycloaliphatic paraffins. (C 3 ) may be either (i) water, (ii) a C 1 to C 20 monohydric alcohol, (iii) a ketone having up to 20 carbon atoms, (iv) a carboxylic acid ester having up to 10 carbon atoms or (v) an aliphatic, alicyclic or aromatic ether having up to 20 carbon atoms. Examples are methanol, 2-ethyl hexanol, cyclohexanol, cyclohexanone, benzyl alcohol, ethyl acetate and acetophenone. (C 4 ) may be a C 1 to C 4 monohydric alcohol, preferably methanol, in combination with a hydrocarbon solvent. Preferred solvents (C) comprise ethylene glycol, a mixture of ethylene glycol and 2-ethyl hexanol and a mixture of methanol and toluene. Optional component (D) is a lubricating oil. The lubricating oil may suitably be an animal, a vegetable or a mineral oil. Suitably the lubricating oil is a petroleum - derived lubricating oil, such as a naphthenic base, paraffin base or mixed base oil. Solvent neutral oils are particularly suitable. Alternatively, the lubricating oil may be a synthetic lubricating oil. Suitable synthetic lubricating oils include diesters such as di-octyl adipate, di-octyl sebacate and tri-decyladipate, or polymeric hydrocarbon lubricating oils, for example liquid polyisobutenes and poly-alpha olefins. Component (E) is carbon dioxide, added subsequent to each addition of component (B). Carbon dioxide may be added in the form of a gas or a solid, preferably in the form of a gas. In gaseous form it may suitably be blown through the reaction mixture. Component (F) is either a basic compound or a salt of at least one of either lithium and potassium, Basic metal compounds include the hydroxides, oxides and alkoxides of the metals. Suitable salts of the metals include the carboxylate salts, for example the formates, acetates and propionates. Optional component (G) is G(i) a carboxylic acid of formula (V) as defined above or an ester, acid anhydride or a salt thereof, or G(ii) a poly-carboxylic acid containing from 36 to 100 carbon atoms, or an ester, acid anhydride or a salt thereof. The amount of the aforesaid acid should be sufficient to provide from 2 to 40% by weight based on the weight of the concentrate. Preferably R 1 in the carboxylic acid of formula (V) is unbranched alkyl or alkenyl. Preferred acids of formula (V) are those wherein R 1 is a C 10 to C 24 , more preferably C 18 to C 24 , straight chain alkyl, and R 2 is hydrogen. Examples of suitable saturated carboxylic acids of formula (V) include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid and lignoceric acid. Examples of suitable unsaturated acids of formula (V) include lauroleic acid, myristoleic acid, palmitoleic acid, oleic acid, gadoleic acid, erucic acid, ricinoleic acid, linoleic acid and linolenic acid. Mixtures of acids may also be employed, for example rape top fatty acids. Particularly suitable mixtures of acids are those commercial grades containing a range of acids, including both saturated and unsaturated acids. Such mixtures may be obtained synthetically or may be derived from natural products, for example cotton oil, ground nut oil, coconut oil, linseed oil, palm kernel oil, olive oil, corn oil, palm oil, castor oil, soyabean oil, sunflower oil, herring oil, sardine oil and tallow. Sulphurised acids and acid mixtures may also be employed. Instead of, or in addition to, the carboxylic acid there may be used an ester or acid anhydride, of the acid, preferably the acid anhydride. Where a salt of the carboxylic acid is used, it is preferred that the salt is an alkaline earth metal salt. It is preferred however to use a carboxylic acid or a mixture of carboxylic acids. A preferred carboxylic acid of formula (V) is stearic acid. Instead of, or in addition to, using (G)(i), G(ii), which is a poly- carboxylic acid containing from 36 to 100 carbon atoms or an ester or acid anhydride thereof can be used. G(ii) is preferably a di- carboxylic acid. Examples are polyisobutene succinic acid or a polyisobutene succinic anhydride. Optional component (H) is a catalyst or promoter for the reaction The catalyst may be an organic compound or an inorganic compound. Suitable organic compounds include (i) organic halides or (ii) organic alkanoates, which may suitably be represented by the formula:- R - X wherein in the formula (VI) X is either halogen, suitably chlorine, bromine or iodine, preferably chlorine, or the group OCOR 1 wherein R 1 is suitably C 1 to C 4 alkyl and R is either an alkyl, aryl or alkaryl group preferably having 3-20 or 6-20 or 7-20 carbons respectively, or a halo-derivative thereof. Alternatively, the organic halide may be an HX salt of an organic base, for example guanidine hydrochloride. A suitable example of an organic halide of the formula (VI) is octyl chloride. Mixtures of (i) and (ii) may also be employed. Suitably the amount of organic compound (G) employed may be up to 2.0% by weight based on the weight of concentrate. Suitable inorganic compound catalysts include inorganic halides, particularly inorganic chlorides, and inorganic alkanoates. Examples of suitable inorganic compound catalysts include calcium acetate, calcium chloride, ammonium chloride, aluminium chloride and zinc chloride, of which calcium chloride and calcium acetate are preferred. Suitably the amounts of the inorganic compound catalyst employed may be up to 2.0% wt/wt based on the weight of the reaction mixture. In order to produce a concentrate of the metal salt it is very much preferred to employ optional component (D), a lubricating oil, though it would be possible to employ component (C) alone and at the completion of the process replace component (C) with component (D) if desired. For the production of overbased metal salts in general it is preferred to utilise components (G) and (H) and for the production of the highly overbased salts (TBN greater than 300) it is very much preferred to utilise components (G) and (H). Preferably the carboxylic acid(s) having the formula (V), or the poly-carboxylic acid or an ester, acid anhydride or salt thereof is incorporated in an amount of 10% to 40%, more preferably 12 to 20%, for example about 16%, by weight based on the weight of the additive concentrate. An advantage of incorporating greater than 10% of the carboxylic acid or derivative thereof is generally that a relatively lower concentrate viscosity results. Suitably the elevated temperature at which the components are reacted will be in the range from 50 to 250, preferably from 130 to 165°C. The pressure may suitably be atmospheric, subatmospheric or superatmospheric. The overbased salt may be recovered as a concentrate in lubricating oil by conventional means, suitably by distillative stripping of component (C). Finally, it is preferred to filter the concentrate so-obtained. According to another aspect of the present invention there is provided a finished lubricating oil composition comprising a lubricating oil and an overbased metal salt as hereinbefore described in an amount up to 10% by weight of the composition. Preferably the finished lubricating oil composition contains sufficient of the overbased metal salt to provide a TBN in the range from 0.5 to 150. The amount of overbased metal salt present in the finished lubricating oil will depend on the nature of the final use. Thus, for marine lubricating oils the amount of salt present may suitably be sufficient to provide a TBN of 9 to 100 and for automobile engine lubricating oils the amount may suitable be sufficient to provide a TBN of 4 to 20. The finished lubricating oil may also contain effective amounts of one or more other types of conventional lubricating oil additives, for example viscosity index improvers, anti-wear agents, antioxidants, dispersants, rust inhibitors, pour-point depressants, or the like, which may be incorporated into the finished lubricating oil composition either directly or through the intermediary of the concentrate composition. In another aspect the present invention provides a method of reducing wear in a part of an internal combustion engine which is moveable relative to another part of the engine and susceptible to wear thereby which method comprises applying to the moveable part of the engine an overbased metal salt as hereinbefore described. The internal combustion engine may suitably be an automobile engine, a marine engine or any other engine, for example an aeroplane engine. The engine may be either a spark ignition, e.g. a gasoline, engine or a spark compression, e.g. a diesel, engine. A part of an internal combustion engine which is moveable relative to another part is for example a piston within a cylinder. Another aspect of the present invention is the use of an overbased metal salt as hereinbefore described for reducing wear in a part of an internal combustion engine which is moveable relative to another part of the engine and susceptible to wear thereby. In a final aspect the present invention provides an internal combustion engine fuel composition comprising a major proportion by weight of an internal combustion engine fuel and a minor proportion by weight of an overbased metal salt as hereinbefore described. The internal combustion engine fuel may be fuel suitable for an engine of either the spark ignition type (gasoline) or the spark compression type (diesel). The fuel composition may additionally contain additives known in the art. The invention will now be further illustrated by reference to the following examples. The term "AV" is used to denote the Total Alkalinity Value in mg KOH/g as measured by the method of ASTM D2896. The viscosity was measured by the method of ASTM D445. In numerical terms the AV corresponds to the TBN (Total Base Number). Example 1 70TBN 500N HVI solutions of ADX 410 and a potassium-containing calcium phenate concentrate containing 2.2% weight potassium obtained in the manner of Example 2 of EP-A-0 699 740 were treated with (i) 4.5% wt, (ii) 5.0% wt. and (iii) 5.5% wt. concentrated sulphuric acid in the manner described in Example 6 of EP-A-0 699 740. Pin wear rates and friction coefficients were determined using the Cameron-Plint TE-77 high frequency friction machine as used in Example 6 of EP-A-0 699740. For ADX 410 the test period was 6.5 hours whereas for the potassium-modified calcium phenate the test period was 12.5 hours. The difference in these periods merely reflects the different times required to achieve stable operability. The results of the tests are given in Table 1. Phenate % wt. H 2 SO 4 % wt. H 2 SO 4 4.5 I 5.0 5.5 4.5 5.0 5.5 Wear rate/10 -17 m 3 /Nm Friction coefficient ADX 410 0.0 6.1 10.7 0.069 0.082 0.086 K/Ca phenate (2.2% wt K) 0.0 2.9 3.4 0.044 0.067 0.071 Reference to the Table shows that in terms of wear rate and friction coefficient the potassium-containing calcium phenate is superior to ADX 410. Example 2 400 TBN calcium potassium calixarate An apparatus was set up consisting of a 1 litre wide neck round bottomed Quickfit flange flask with flange clip, flange lid incorporating an overhead stirrer, PTFE gland and stainless steel paddle, still head connected to double surface condenser with vacuum receiver, adaptor and 500ml round bottom receiver flask cooled by a butanol/CO 2 (s) bath and a thermocouple/Eurotherm/l litre mantle heating system. The apparatus between the top of the mantle and the condenser was lagged with cotton wool. A calixarene made from a mixture of 64% p-dodecylphenol, 20% 2,6-di-tertiary butylphenol, 16% o-dodecylphenol and o-p-dodecylphenol as a 50% solution in SN 150 mineral oil (M. wt. 263.5 per unit, 123g, 0.233 moles, 1 equiv.) was charged to the vessel along with potassium hydroxide (6.2g, 0.110 moles, 0.47 equivs), stearic acid (85g, 0.3 moles, 1.29 equivs), calcium acetate (6.0g, 38 mmol, 0.16 equivs), a mixture of dodecylphenols (80% para-, the rest ortho- and ortho-para-di-, 9.0g, 34 mmol, 0.14 equivs), SN150 lubricating oil (solvent, 18.4g) and 2-ethylhexanol (solvent, 222g). The mixture was heated with stirring to 130°C/11" Hg vacuum for 10 minutes and then the reaction mixture was cooled to 100°C. Calcium hydroxide (90g, 1.21 moles, 5.18 equivs) was then added and the reaction heated to 140°C for 1 hour at 11"Hg. Ethylene glycol (42g, 1.476 moles, 6.33 equivs) was then added and the reactants cooled to 130°C and held with 11 "Hg for 10 minutes. The vacuum was then released and the reactants carbonated at 130°C using a dip tube connected to a Buchner flask containing solid carbon dioxide (120g, 2.73 moles, 11.7 equivs) heated by an IR heat lamp. Carbonation was complete after 1 hour and the mixture had become clear. The reaction mixture was then heated to 200°C at 29"Hg and all the solvent was removed. The resulting orange-brown liquid had a crude sediment content of 3.6% and was filtered through a 1/2" celite pad, to give a product having the following analysis: AV = 392 mgKOH/g Ca content = 13.16% K content = 1.12% Comparison Test Example 2 was repeated except that the addition of potassium hydroxide was omitted. The resulting product was a 378 AV (mgKOH/g) calcium calixarate containing 13.5 % by weight calcium. This is not an example according to the invention because the only metal moiety in the overbased calixarate is calcium. Example 3 70 TBN 500N HVI solutions of the calcium potassium calixarate of Example 2, the potassium-containing calcium phenate (2.2% wt K) as used in Example 1, ADX 410, and the calcium calixarate (AV 378, Ca content 13.5% wt) of the Comparison Test were treated with (i) 3.5% wt and (ii) 5.0% wt concentrated sulphuric acid in the manner described in Example 6 of EP-A-0 699 740. Pin wear rates, plate wear rates and friction coefficients were determined using the Cameron-Plint TE-77 high frequency friction machine as used in Example 6 of EP-A-0 699 740. The test period was 12.5 hours. The results of the test are given in Table 2. With reference to Table 2, the results demonstrate that at 5 % wt H 2 SO 4 the incorporation of potassium into the calcium calixarate significantly reduces both plate and pin wear. In fact, in terms of plate and pin wear, the calcium potassium calixarate is markedly better than the commercial calcium phenate (ADX 410) which is significantly better than the calcium calixarate. The potassium-containing calcium calixarate provides lower friction coefficients 5%wt H 2 SO 4 at than either the calcium calixarate or ADX 410.

Claims: An overbased metal salt of hydrocarbyl-substituted non-sulphurised phenol, a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin wherein the metal moiety comprises a first metallic component which is at least one alkaline earth metal and a second metallic component which is at least one of lithium and potassium, the weight ratio of the first metal component to the second metal component being in the range from 1000:1 to 2:1. An overbased metal salt according to claim 1 wherein the first metallic component is calcium. An overbased metal salt according to either one of the preceding claims, wherein the weight ratio of the first metallic component to the second metallic component is in the range from 150:1 to 2:1. A concentrate composition which comprises at least one overbased metal salt as claimed in claim 1, and a solvent therefor, the overbased metal salt comprising from greater than 10 to less than 90% by weight of the composition. A concentrate composition according to claim 4, wherein the solvent for the overbased metal salt is a lubricating oil. A concentrate composition according to either one of claim 4 or claim 5, having a TBN in the range from 75 to 500. A concentrate composition according to claim 5, comprising a lubricating oil and a metal non-sulphurised alkyl phenate, the concentrate having a TBN of greater than 300 and a viscosity at 100°C of less than 1000 cSt, the metal being either a mixture of calcium and either lithium or potassium in a weight ratio of calcium to either lithium or potassium in the range from 6:1 to 25:1. A process for the production of an overbased metal salt as claimed in claim 1 which process comprises reacting at elevated temperature component (A) either (i) an alkaline earth metal hydrocarbyl-substituted non-sulphurised phenate, or (ii) an alkaline earth metal salt of a calixarene having a substituent hydroxyl group or groups available for reaction with a metal base, or (iii) an alkaline earth metal salt of a linear phenol/formaldehyde resin, or (iv) the precursors of either (i) (ii) or (iii), component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction, component (C) a solvent comprising either:- (C1) either (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di-(C 2 to C 4 ) glycol, (iii) a tri- (C 2 to C 4 ) glycol or (iv) a mono- or poly-alkylene glycol alkyl ether of the formula:- R 3 (OR 4 ) x OR 5 wherein in the formula (IV) R 3 is a C 1 to C 6 alkyl group, R 4 is an alkylene group, R 5 is hydrogen or a C 1 to C 6 alkyl group and x is an integer in the range from 1 to 6, either alone or in combination with either (C2) a hydrocarbon solvent or (C3) either (i) water, (ii) a C 1 to C 20 monohydric alcohol, (iii) a ketone having up to 20 carbon atoms, (iv) a carboxylic acid ester having up to 10 carbon atoms or (v) an ether having up to 20 carbon atoms, or, (C4) a C 1 to C 4 monohydric alcohol in combination with a hydrocarbon solvent, optional component (D) a lubricating oil, component (E) carbon dioxide added subsequent to the, or each, addition of component (B), component (F) either a basic compound or a salt of at least one of either lithium and potassium, optional component (G) sufficient to provide from 2 to 40% by weight based on the weight of the concentrate of at least one compound which is G (i) a carboxylic acid or an acid anhydride, ester or salt thereof, said acid having the formula (V) wherein R 1 is a C 10 to C 24 alkyl or alkenyl group and R 2 is hydrogen, a C 1 to C 4 alkyl group or a CH 2 COOH group, or G (ii) a poly-carboxylic acid containing from 36 to 100 carbon atoms or an acid anhydride, ester or salt thereof, optional component (H) a catalyst or promoter for the reaction, the amounts of components (B) and (F) being such as to produce an overbased metal salt wherein the weight ratio of the alkaline earth metal of component (B) to the metal of component (F) is in the range from 1000:1 to 2:1. A finished lubricating oil composition comprising a lubricating oil and an overbased metal salt as claimed in claim 1 in an amount up to 10% by weight of the composition. A method of reducing wear in a part of an internal combustion engine which is moveable relative to another part of the engine and susceptible to wear thereby which method comprises applying to the moveable part of the engine an overbased metal salt as claimed in claim 1. The use of an overbased metal salt as claimed in claim 1 for reducing wear in a part of an internal combustion engine which is moveable relative to another part of the engine and susceptible to wear thereby. An internal combustion engine fuel composition comprising a major proportion by weight of an internal combustion engine fuel and a minor proportion by weight of an overbased metal salt as claimed in claim 1.

Inventors: COOK STEPHEN JAMES, LEAHY RICHARD, COOK, STEPHEN JAMES, LEAHY, RICHARD
Applicants: LUBRIZOL ADIBIS HOLDINGS LTD, LUBRIZOL ADIBIS HOLDINGS (UK) LIMITED
Application year: 1995
Main classification: C10M159
IPC codes: C08G8, C10M145, C10M159, C10N10