DE3781126T2 - SULFURIZED EARTH ALKALINE METAL ALKYLPHENOLATES, THEIR PRODUCTION AND THEIR USE. - Google Patents

Abstract

An additive concentrate suitable for incorporation into a finished lubricating oil composition, the additive concentrate comprising: (a) a lubricating oil, (b) a lubricating oil soluble sulphurised alkaline earth metal hydrocarbyl phenate modified by incorporation of from greater than 2 to 35% by weight based on the weight of the composition of either (i) at least one carboxylic acid having the formula:- R - @@ - COOH (I) wherein R is a C10 to C24 alkyl or alkenyl group and R<1> is either hydrogen, as C1 to C4 alkyl group or a -CH2-COOH group, or an anhydride, acid chloride or ester thereof or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride, acid chloride or ester thereof, the composition having a TBN greater than 300.

Description

The present invention relates generally to the preparation of sulfurized alkaline earth metal hydrocarbyl phenate additive concentrates and their use as lubricating oil additives. More particularly, the present invention relates to the preparation of sulfurized alkaline earth metal hydrocarbyl phenate-containing additive concentrates having a high total base number (TBN) and an acceptable viscosity from sulfurized alkaline earth metal hydrocarbyl phenates having lower total base numbers.

In the internal combustion engine, byproducts from the combustion chamber often escape past the piston and mix with the lubricating oil. Many of these byproducts form acidic materials within the lubricating oil. This is particularly pronounced in diesel engines that run on low-quality, high-sulfur fuels, which produce corrosive acids during combustion. The acids thus introduced into the lubricating oil can include sulfuric acids, which are formed by the oxidation of sulfur, hydrohalic acids, which come from halogenated lead scavengers in the fuel, and nitric acids, which are formed by the oxidation of atmospheric nitrogen inside the combustion chamber. Such acids cause sludge deposits and corrosion of bearings and engine parts, leading to rapid wear and early engine failure.

One class of compounds commonly employed to neutralize the acidic materials and disperse the sludge within the lubricating oil is formed by sulfurized metal alkylphenates, wherein the metal is an alkaline earth metal such as calcium, magnesium or barium. Both "normal" and "overbased" sulfurized alkaline earth metal alkylphenates have been employed. The term "overbased" is used to describe those sulfurized alkaline earth metal alkylphenates wherein 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 1, and usually greater than 1.2, and may be as high as 4.5 or more. In contrast, the equivalent ratio of alkaline earth metal residue to phenol residue in "normal" alkaline earth metal alkylphenates is 1. Consequently, the "overbased" material contains more than 20% of the alkaline earth metal present in the corresponding "normal" material in excess. For this reason, "overbased" sulfurized alkaline earth metal alkylphenates have a greater capacity to neutralize acidic material than do the corresponding "normal" alkaline earth metal alkylphenates.

Many processes are described in the art for preparing both "normal" and "overbased" sulfurized metal alkylphenates. One such process for preparing "overbased" alkylphenates, commonly referred to as the "single lime addition" process, involves reacting an alkylphenol in the presence of lubricating oil, sulfur, a hydroxyl compound and an excess of alkaline earth metal hydroxide (over the stoichiometric amount required to neutralize the alkylphenol) to form an intermediate, followed by carbonation, overhead distillation (to remove the unreacted hydroxyl compound) and filtration. The preparation of the intermediate is accompanied by a significant increase in viscosity, whereas the subsequent carbonation lowers the viscosity to a relatively low level. The increase in viscosity which accompanies the formation of the intermediate is undesirable because the reaction mixture is difficult to stir, to the detriment of subsequent reactions. Although this increase in viscosity can be controlled to an acceptable level by incorporating less alkaline earth metal hydroxide in the reaction, the overbased alkylphenate product necessarily has a reduced neutralization capacity. To obtain a product with a high neutralization capacity and at the same time control the viscosity of the intermediate within acceptable limits, the alkaline earth metal hydroxide can be added in two (commonly referred to as the "double lime addition" process) or in three separate reaction steps followed by carbonation steps. However, this process involves relatively long batch times. Another alternative is to use viscosity reducing agents such as tridecanol, 2-ethylhexanol, or hydroxylic solvents having a similar boiling range in the preparation of the intermediate, but such an agent increases the raw material cost of the process. The highest total base number (TBN), expressed in mg KOH/g, consistent with an acceptable viscosity generally achievable by prior art processes is about 300, although prior art TBNs generally range from 200 to 300. It would clearly be a desirable goal to produce compositions of sulfurized alkaline earth metal alkylphenates having a high TBN, that is, a TBN of greater than 200 and preferably greater than 350. It would also be a desirable goal to produce such materials from sulfurized alkaline earth metal alkylphenates having a lower TBN.

To date, it has not been possible to obtain products with such a high TBN, since the use of higher concentrations of alkaline earth metal base results in highly viscous products which, instead of being "diluted", are rendered insoluble by subsequent carbonation attempts using an excess of carbon dioxide. We have achieved these goals and thereby obtained compositions which have a TBN of greater than 300 and in some cases greater than 350, while at the same time maintaining an acceptable viscosity, that is, a viscosity of less than 1,000 cSt and insolubility is avoided by incorporating in the reaction mixture containing a sulfurized alkaline earth metal alkylphenate at least one carboxylic acid or an acid derivative thereof having at least 10 carbon atoms in the molecule.

The use of carboxylic acids in the preparation of sulfurized alkaline earth metal alkyl phenols is not new, see for example US-A-4 049580 and EP-A-0 094 814.

US-A-4 049 580 describes the preparation of an overbased magnesium detergent by a process in which carbon dioxide is introduced into a reaction mixture which:

(a) 15 to 40% by weight of a sulfurized phenol or thiophenol having one or more hydrocarbyl substituents, or of a phenol or thiophenol having one or more hydrocarbyl substituents, or of said phenol or thiophenol having one or more hydrocarbyl substituents together with sulfur,

(b) 5 to 15% by weight of an organic sulfonic acid, an organic sulfonate or an organic sulfate,

(c) 5 to 15% by weight of a glycol, a monohydric (C₁-C₅)-alkanol or a (C₂-C₄)-alkoxyalkanol,

(d) 2 to 15% by weight of a magnesium hydroxide or an active magnesium oxide,

(e) at least 0.1% by weight of a (C₁-C₁₈)carboxylic acid, and

(f) at least 10% by weight of a diluent oil (including that present in components (a) and (b)).

The amount of carboxylic acid (component (e)) is preferably in the range of 0.5 to 2.0 wt.%. The product produced by this reaction should have a TBN of about 200 to 250, e.g. about 225.

EP-A-0 094 814 describes an additive concentrate for incorporation into a lubricating oil composition comprising lubricating oil and 10 to 90% by weight of a sulphurised overbased alkaline earth metal hydrocarbyl phenate which is treated either during the "overbasing" process or subsequently with 0.1 to 10, preferably 2 to 6% by weight (based on the weight of the additive concentrate) with an acid of the formula

(wherein R represents a straight chain (C₁₀-C₂₄)alkyl or alkenyl group and R¹ represents hydrogen, a (C₁-C₄)alkyl group or a -CH₂-COOH group) or with an anhydride or a salt thereof. The aim of the invention of EPA-0 094814 is to overcome the problems associated with many additive concentrates containing overbased additives, namely the lack of stability which forms the basis for sedimentation and foaming problems. The problem of EP-A-0 094 814 is not to produce phenate additive concentrates having a TBN of more than 200 and in fact the phenate additive concentrates produced by the process of the invention, although they overcome the problems of stability and foaming, have TBN values of less than 300.

Our European application with publication number 0 095 322 contains a process for the preparation of either an alkaline earth metal alkylphenate or a sulfurized alkaline earth metal alkylphenate, which process comprises reacting at elevated temperature in the presence or absence of sulfur, an alkylphenol with an alkaline earth metal base in the presence of either an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether of the formula:

as solvent, wherein R represents a (C₁-C₆)alkyl group, R¹ is alkylene, R² is hydrogen or (C₁-C₆)alkyl and x is an integer in the range from 1 to 6, as solvent and an inorganic halide as catalyst. It is said to be preferable to add a small amount, suitably up to 2% w/w, of an acid, with stearic acid being a suitable acid. The addition of stearic acid to the reactants is said to increase the ability of alkylphenates to reduce emulsion formation in water.

It can be summarized that the prior art in which carboxylic acids are used does not address the problem of producing overbased sulfurized alkyl earth metal hydrocarbylphenates with a TBN of more than 300 and an acceptable viscosity.

Our parallel European application number 0 271 262 with the same priority date as the present application provides an additive concentrate suitable for incorporation into a finished lubricating oil composition, which additive concentrate:

(a) a lubricating oil,

(b) a lubricating oil soluble, sulfurized or non-sulfurized alkaline earth metal hydrocatalyst phenate which is prepared by incorporating from more than 2 to less than 40% by weight, based on the weight of the concentrate, of either

(i) at least one carboxylic acid having the formula:

wherein R represents a (C₁₀-C₂₄)alkyl or alkenyl group and R¹ represents either hydrogen, a (C₁-C₄)alkyl group or a -CH₂-COOH group, or an anhydride or ester thereof or

(ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an anhydride or ester thereof,

wherein the composition has a TBN of more than 300.

In one aspect, the present invention provides a process for preparing an additive concentrate suitable for incorporation into a finished lubricating oil composition, which additive concentrate:

(a) a lubricating oil,

(b) a lubricating oil soluble sulfurized alkaline earth metal hydrocarbylphenate which is prepared by incorporating more than 2 to 35% by weight, based on the weight of the concentrate, of either

(i) at least one carboxylic acid having the formula:

wherein R represents a (C₁₀-C₂₄)alkyl or -alkenyl group and R¹ represents either hydrogen, a (C₁-C₄)alkyl group or a -CH₂-COOH group or an anhydride or ester thereof or

(ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an anhydride or ester thereof,

wherein the concentrate has a TBN of more than 300 and a viscosity at 100ºC of less than 1000 mm²·s⊃min;¹ (cSt), which process comprises reacting

(A) a sulfurized alkaline earth hydrocarbyl phenate having a lower TBN than the finished additive concentrate,

(B) an alkaline earth metal base which is either added in whole to the original reactants or added in part to the original reactants and the remainder is added in one or more parts in a subsequent step or steps in the reaction,

(C) either a polyhydric alcohol having 2 to 4 carbon atoms, a di- or tri(C₂-C₄)glycol, an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether,

(D) a lubricating oil,

(E) Carbon dioxide added subsequently to the addition or to each addition of component (B) and sufficient

(F) to contain from more than two to 35% by weight, based on the weight of the concentrate, of either

(i) at least one carboxylic acid having the formula:

wherein R represents a (C₁₀-C₂₄)alkyl or alkenyl group and R¹ represents either hydrogen, a (C₁-C₄)alkyl group or a -CH₂-COOH group, or an anhydride or ester thereof or

(ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an anhydride or ester thereof,

at elevated temperature, wherein the weight ratios of components (A) to (F) are such that a concentrate having a TBN of more than 300 is produced.

The process of the invention is advantageous because it provides a method to upgrade prior art low TBN or off-specification products to high TBN products having acceptable viscosity. Since, in contrast to the processes for preparing sulfurized alkaline earth metal alkylphenates which use the Reaction of an alkylphenol and sulfur by more conventional routes, furthermore, no hydrogen sulfide is formed during the performance of the process of the invention, the problem of hydrogen sulfide waste is avoided, thereby enabling production in environmentally sensitive areas and the use of less sophisticated equipment.

Component (a) of the concentrate is a lubricating oil. The lubricating oil may suitably be either an animal oil, a vegetable oil or a mineral oil. Suitably the lubricating oil may be a petroleum-derived lubricating oil such as a naphthenic, paraffinic 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 synthetic lubricating oils from esters which include oils diesters such as dioctyl adipate, dioctyl sebacate and tridecyl adipate or lubricating oils from polymeric hydrocarbons, for example liquid polyisobutenes and poly-alpha-olefins. The lubricating oil may suitably comprise from 10 to 90%, preferably from 10 to 70%, by weight of the concentrate.

Component (b) is a lubricating oil soluble sulfurized alkaline earth metal hydrocarbyl phenate modified by incorporating from greater than 2 to 35% by weight of the concentrate of either (i) or (ii). Suitably, the alkaline earth metal may be strontium, calcium, magnesium or barium, preferably calcium, barium or magnesium, more preferably calcium.

The hydrocarbyl radical of the sulfurized alkaline earth metal hydrocarbylphenate is preferably obtained from at least one alkylphenol. The alkyl groups of the alkylphenol can be branched or unbranched. Suitable alkyl groups contain 4 to 50, preferably 9 to 28 carbon atoms. A particularly suitable alkylphenol is the C₁₂alkylphenol, which is obtained by alkylating phenol with propylene tetramer.

The sulfurized alkaline earth metal hydrocarbylphenate is modified by incorporating either (i) or (ii). As for (i), this is at least one carboxylic acid of formula (i) or an acid anhydride or ester thereof. Preferably, R in formula (i) is a straight chain alkyl or alkenyl group. Preferred acids of formula (i) are those wherein R is a straight chain C₁₀ to C₂₄ alkyl group, more preferably a straight chain C₁₈ to C₂₄ alkyl group and R¹ is hydrogen. Examples of suitable saturated carboxylic acids of formula (i) include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and lignocerotic acid. Examples of suitable unsaturated acids of formula (i) include lauryl oleic acid, myristic oleic acid, palmitic oleic acid, oleic acid, gadoleic acid, erucic acid, cystine oleic acid, linoleic acid and linolenic acid. Mixtures of acids may also be used, for example rapeseed pot fatty acids. Particularly suitable mixtures of acids are those of commercial grade which contain a range of acids including both saturated and unsaturated acids. Such mixtures may be prepared synthetically or they may be obtained from natural products, for example from cottonseed oil, peanut oil, coconut oil, linseed oil, palm kernel oil, olive oil, corn oil, palm oil, castor oil, soybean oil, sunflower oil, herring oil, sardine oil and tallow. Sulfurized acids and acid mixtures may also be used. Instead of the carboxylic acid or in addition thereto, both the acid anhydride and the ester derivatives of the acid, preferably the acid anhydride, may be used. However, it is preferred to use a carboxylic acid or a mixture of carboxylic acids. A preferred carboxylic acid of formula (i) is stearic acid.

Instead of (i) or in addition thereto, the sulfurized alkaline earth metal hydrocarbyl phenate can be modified by incorporating (ii) which is a di- or polycarboxylic acid having 36 to 100 carbon atoms, an acid anhydride or an ester derivative thereof, preferably an acid anhydride thereof.

Preferably (ii) is a polyisobutene succinic acid or a polyisobutene succinic anhydride.

Preferably, the carboxylic acid(s) of formula (i), the di- or polycarboxylic acid or acid anhydride or ester thereof are incorporated in an amount of from greater than 10% to 35%, more preferably from 12% to 20%, for example about 16%, by weight based on the weight of the concentrate. An advantage of incorporating more than 10% of carboxylic acid or a derivative thereof is generally a relatively lower concentrate viscosity.

Suitably, the alkaline earth metal may be present in the concentrate in an amount Range of 10 to 20 wt.%, based on the weight of the concentrate.

Suitably, sulphur may be present in the concentrate in an amount in the range of from 1 to 6% by weight, preferably from 1.5 to 3% by weight, based on the weight of the concentrate.

Suitably, carbon dioxide may be present in the concentrate in an amount of from 5 to 20% by weight, preferably from 9 to 15% by weight, based on the weight of the concentrate.

Preferably, the TBN of the concentrate is greater than 350, more preferably greater than 400.

Preferably, the concentrate may have a viscosity, measured at 100°C, of less than 1,000 cSt, preferably less than 750 cSt, more preferably less than 500 cSt.

Component (A) of the reaction mixture is a sulfurized alkaline earth metal hydrocarbyl phenate having a lower TBN than the final product, i.e., generally less than 300. Any sulfurized alkaline earth metal hydrocarbyl phenate may be used. The sulfurized alkaline earth metal hydrocarbyl phenate may be carbonated or non-carbonated. The alkaline earth metal moiety and the hydrocarbyl phenate moiety of the sulfurized alkaline earth metal hydrocarbyl phenate may be suitably as described hereinabove. Methods for preparing sulfurized alkaline earth metal hydrocarbyl phenates are well known in the art. Alternatively, the precursors of a sulfurized alkaline earth metal hydrocarbyl phenate may be employed in the form of a non-sulfurized alkaline earth metal hydrocarbyl phenate.

The alkaline earth metal base (component B) may suitably be an alkaline earth metal oxide or hydroxide, preferably the hydroxide. Calcium hydroxide may be used, for example, in the form of slurried lime. Preferred alkaline earth metals are calcium, magnesium and barium, and more preferably calcium is used. The alkaline earth metal base must be added in an amount which is sufficient relative to component (A) to give a product having a TBN of more than 300, preferably more than 350. This amount will depend on a number of factors including the nature of the sulfurized alkaline earth metal hydrocarbyl phenate. Typically, the weight ratio of component (B) to component (A) may suitably be in the range of from 0.1 to 50, preferably from 0.2 to 5. The alkaline earth metal base (B) may be added in whole to the original reactants, or added in one part to the original reactants and added to the solid in one or more parts in a subsequent step or steps in the process. Preferably, component (B) is added in a single addition to the original reactants.

Component (C) is either a polyhydric alcohol having 2 to 4 carbon atoms, a di- or tri(C₂-C₄)glycol, an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether. 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- or tri(C₂-C₄)glycol may suitably be either diethylene glycol or triethylene glycol. The alkylene glycol alkyl ether or polyalkylene glycol alkyl ether may suitably have the formula

wherein R represents a (C₁-C₆)alkyl group, R¹ represents an alkylene group, R² represents hydrogen or (C₁-₆)alkyl and x is an integer in the range from 1 to 6. Suitable solvents of formula (II) include the monomethyl or dimethyl ethers of ethylene glycol, diethylene glycol, triethylene glycol or tetraethylene glycol. A particularly suitable solvent is methyldigol (CH₃OCH₂CH₂OCH₂CH₂OH). Mixtures of glycols and glycol ethers of formula (II) may also be used. When using a glycol or a glycol ether of formula (II) as solvent, it is preferred to use in association therewith an inorganic halide, for example ammonium chloride, and a lower, i.e. (C₁-C₄)carboxylic acid, for example acetic acid. Preferably, component (C) is either ethylene glycol or methyldigol, the latter in combination with ammonium chloride and acetic acid.

Component (D) is a lubricating oil as described hereinabove with reference to the concentrate composition.

Component (E) is carbon dioxide, which is in the form of a gas or of a solid, preferably in the form of a gas. In gaseous form it can conveniently be passed through the reaction mixture. The Applicant has found that in general the amount of carbon dioxide incorporated also increases with increasing concentrations of component (F). The carbon dioxide is preferably added following a single addition of component (B), at the end of the reaction between components (A), (B), (C), (D) and (F).

Component (F) is either a carboxylic acid of formula (I), a di- or polycarboxylic acid having 36 to 100 carbon atoms, or an acid anhydride or ester thereof as described with reference to the concentrate composition hereinbefore. The amount of the aforementioned compounds required to provide from more than 2 to 35% by weight based on the weight of the concentrate will, as a first approximation, correspond to the amount desired in the concentrate. In calculating this amount, some margin should be left, for example due to the loss of water from carboxylic acids.

The reaction can be carried out in the presence of a diluent. Suitable diluents are liquids which have a volatility corresponding to the conduct of the process, i.e. which have a volatility such that they can be easily removed from the reaction mixture at the end of the reaction. Examples of suitable diluents include 2-ethylhexanol, isooctanol, isoheptanol and tridecanol.

Further sulphur, i.e. additional sulphur to that already present through component (A), can be added to the reaction mixture. One advantage of adding further sulphur is that it increases the amount of sulphur in the concentrate, which may be desirable for certain applications. On the other hand, the addition of sulphur leads to the formation of hydrogen sulphide, which to some extent reduces the advantage of the invention as mentioned hereinbefore.

Preferably, the reaction is carried out in the presence of a further component which is a catalyst for the reaction. As a catalyst, an inorganic halide can be used, which is suitably either a hydrogen halide, an aluminum halide or a metal halide. Suitably, the metal radical of the metal halide can be zinc, aluminium or an alkaline earth metal, preferably calcium. Of the halides, chloride is preferred. Suitable catalysts include hydrogen chloride, calcium chloride, ammonium chloride, aluminium chloride and zinc chloride, preferably calcium chloride. Suitably the amount of catalyst employed may be up to 2.0% w/w.

Suitably, the reaction of components (A) to (F) and also the carbonation reaction may be carried out at elevated temperatures in the range of from 120 to 200, preferably from about 120 to 165°C, although the actual temperatures selected for the reaction of components (A) to (F) and the carbonation may differ if desired. The pressure may be atmospheric, subatmospheric or superatmospheric.

The concentrate can be obtained by conventional means, for example by distillative stripping of component (C) and the diluent (if present).

Finally, it is preferred to filter the concentrate so obtained. In general, the process of the invention will produce a concentrate with an acceptable viscosity, that is, a viscosity of less than 1,000 cSt at 100°C, and it can produce concentrates with a viscosity of less than 750 or 500 cSt at 100°C. In addition, the concentrates generally have desirable viscosity index properties. Such viscometric properties are advantageous because they facilitate processing (including filtration) of the concentrate. However, it is also possible to produce concentrates with a viscosity higher than 1,000 cSt at 100°C, generally with higher TBN values. Filtration of such concentrates presents a problem which can be overcome by adding a diluent prior to filtration and stripping the diluent after filtration. Alternatively or additionally, the concentrate may be diluted with lubricating oil and still maintain a TBN of more than 300, particularly if the TBN of the concentrate after manufacture is high, for example, above 400.

In a further aspect, the present invention provides an additive concentrate suitable for incorporation into a finished lubricating oil, which concentrate is prepared by reacting

(A) a sulfurized alkaline earth metal hydrocarbylphenate having a lower TBN as the finished additive concentrate,

(B) an alkaline earth metal base which is either added in whole to the original reactants or added in part to the original reactants and the remainder is added in one or more parts in a subsequent step or steps in the reaction,

(C) either a polyhydric alcohol having 2 to 4 carbon atoms, a di- or tri(C₂-C₄)glycol, an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether,

(D) a lubricating oil,

(E) Carbon dioxide added subsequently to the addition or to each addition of component (B) and sufficient

(F) to contain from more than two to 35% by weight, based on the weight of the concentrate, of either

(i) a carboxylic acid of formula (I) or an acid anhydride or ester thereof or of

(ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an acid anhydride or ester thereof,

obtainable at elevated temperature, wherein the weight ratio of the components (A) to (F) is such as to produce a concentrate having a TBN of more than 300 and a viscosity at 100ºC of less than 1,000 mm²·s⊃min;¹ (cSt).

In a final aspect, the present invention provides a finished lubricating oil composition, which composition comprises a lubricating oil and a sufficient amount of additive concentrate prepared in the manner described hereinabove to provide a TBN in the range of 0.5 to 120.

Preferably, the finished lubricating oil composition contains a sufficient amount of the concentrate to ensure a TBN in the range of 0.5 to 100.

The amount of additive concentrate present in the finished lubricating oil will depend on the nature of the end use. Thus, for marine lubricating oils, the amount of concentrate composition present may suitably be sufficient to provide a TBN in the range 9 to 100 and for automotive engine lubricating oils, the amount may suitably be sufficient to provide a TBN in the range 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 intermediate route of the concentrate.

In addition to their use as additives for incorporation into lubricating oil compositions, the concentrates of the present invention may also find application as fuel additives.

The invention will now be further illustrated by reference to the following examples.

In all the examples the term "TBN" is used. The TBN is the Total Base Number in mg KOH/g as determined by the method of ASTM D2896.

In all of the examples, unless specifically stated otherwise, a commercially available sulfurized calcium alkylphenate derived from a C12 alkylphenol was employed. The phenate is provided as a solution in lubricating oil which constitutes 36 to 40% w/w of the composition. The composition has a TBN of 250 and the following composition: calcium (9.25% w/w), sulfur (3.25% w/w) and carbon dioxide (4.06% w/w). When the "charge" for any example includes lubricating oil, it is lubricating oil in addition to the lubricating oil already contained in the phenate composition.

The viscosity was measured by the method of ASTM D445.

example 1 Improvement of sulphurised calcium alkylphenate

Batch: Lubricating oil (57 g)

Sulfurized calcium alkylphenate (206 g)

Lime (49 g)

Stearic acid (70 g)

Calcium chloride (4 g)

2-Ethylhexanol (112 g)

The batch was heated to 145-165ºC/700 mm Hg while 36 g of ethylene glycol was added. It was then held at 165ºC/700 mg Hg for one hour. Carbon dioxide (50 g) was added at 165ºC for one hour. The product was cooled to 125ºC/700 mm Hg. Lime (33 g) was added. The temperature was raised to 165ºC/700 mg Hg and held at that temperature for one hour. Carbon dioxide (25 g) was added at 1650 for one hour. The product was then stripped at 200ºC/10 mm Hg. Finally, the product was filtered. It was observed that the filtration rate was very high. 437 g of product and 167 g of distillate were obtained.

The product was analyzed for calcium, sulfur and carbon dioxide content. Its TBN, BPHY150 and viscosity at 100ºC were determined. The BPHV150 is a solubility test. The results of the test are expressed on the scale as 1 (highly soluble; passes), 2 (borderline) and 3 (does not pass).

Results

Calcium = 13.9% w/w (corresponds to 96% of the calcium used retained in the product).

Sulphur = 1.5% w/w (corresponds to 100% of the sulphur used being retained in the product).

Carbon dioxide = 12.3% w/w (corresponds to 96% of the CO2 used retained in the product).

TBN = 395

V₁₀₋₀ = 228 cSt

BPHV150 = 1A

Stearic acid = 16% w/w

This example demonstrates that a low TBN product can be converted by the process of the invention to a high TBN product having an acceptable viscosity.

Example 2

Batch: Sulfurized calcium alkylphenate: 230 g

Lubricating oil : 26 g

Calcium chloride : 3 g

Proceedings

(a) The batch was heated to 100ºC/700 mm Hg. Stearic acid (63 g) was added and the mixture was stirred for 15 minutes.

(b) 2-Ethylhexanol (190 g) was added at 100-110º c/700 mm Hg,

(c) Lime (66 g) was added at 110ºC/700 mm Hg

(d) The mixture was heated to 165ºC/700 mm Hg and ethylene glycol (32 g) was added rapidly (within one minute).

The mixture was kept at 165ºC/700 mm kg for 5 minutes.

(f) Carbon dioxide (66 g) was then added at 165ºC/1 bar,

(g) the solvent was recovered at 200ºC/10 mm kg and

(h) the stripped product was filtered.

Product weights

Raw product: 398 g

Distillate : 236 g

Product composition after filtration

The filtration rate was high.

Calcium: 14.1% w/w

Sulphur: 2.0% w/w

CO₂ : 12.9% w/w

TBN: 399

V₁₀₋₀ : 825 cSt

Stearic acid: 15.8% w/w

Example 3 Charge:

As in example 2.

Proceedings

As in Example 2 except that in steps (d), (e) and (f) the temperature was 145ºC instead of 165ºC.

Product weights

Raw product: 402 g

Distillate : 239 g

Product composition after filtration

Calcium: 13.9% w/w

Sulphur: 1.9% w/w

CO₂ : 13.9% w/w

TBN: 392

V₁₀₋₀ : 206 cSt

Stearic acid: 15.7% w/w

Example 4 Charge:

As in example 2

Proceedings

As in Example 2 except that the temperature in steps (d), (e) and (f) was 130ºC instead of 165ºC.

Product weights

Raw product: 377 g

Distillate : 236 g

Product composition after filtration

Calcium: 13.7% w/w

Sulphur: 2.1% w/w

CO₂ : 13.2% w/w

TBN: 380

V₁₀₋₀ : 99 cSt

Stearic acid: 16.7% w/w

Example 5 Charge:

As in Example 3 except that calcium chloride was omitted.

Proceedings

As in example 3.

Product weights

Raw product: 388 g

Distillate : 239 g

Product composition after filtration

Calcium: 11.9% w/w

Sulphur: 2.1% w/w

CO₂ : 9.0% w/w

TBN: 331

V₁₀₋₀ : 98 cSt

V₄₀ : 1490 cSt

VI : 148

Stearic acid: 16.2% w/w

The filtration step (h) was very difficult.

This example, in comparison with Example 3, demonstrates the desirability of using a catalyst in the process of the invention. Although a lower V₁₀₀₀ was obtained in the absence of a catalyst, this was achieved at the expense of reduced incorporation of calcium and carbon dioxide and, furthermore, filtration was difficult.

Example 6 Charge:

Sulfurized calcium alkylphenate : 253 g

Lubricating oil (100 SN) : 26 g

Calcium chloride : 4 g

2-Ethylhexanol : 190 g

Stearic acid: 40 g

Proceedings

(a) The batch was heated to 120ºC/700 mm Hg and lime (36 g) was then added.

(b) The mixture was heated to 145-165ºC while ethylene glycol (32 g) was added.

(c) The mixture was kept at 165ºC/700 mm Hg for one hour,

(d) Carbon dioxide (44 g) was added at 165ºC/1 bar,

(e) the mixture was cooled to 120ºC and lime (25 g) was added,

(f) the mixture was maintained at 165ºC/700 mm Hg for one hour.

(g) Carbon dioxide (22 g) was added at 165ºC/1 bar.

(h) The solvent was evaporated at 200ºC/10 mm Hg and

(i) the product was filtered. The filtration rate was high.

Product weights

Raw product: 401 g

Distillate : 239 g

Product composition after filtration

Calcium: 14.3% w/w

Sulphur: 2.1% w/w

CO₂ : 11.3% w/w

TBN: 405

V₁₀₋₀ : 1483 cSt

Stearic acid: 10% w/w

This example shows that it is possible to produce a concentrate with a high TBN by incorporating 10% w/w of stearic acid, even though the viscosity is relatively high.

Example 7 Charge

As in Example 6 except that the amount of phenate was increased from 290 g to 268 g and the amount of stearic acid was increased from 40 g to 41 g.

Procedure:

As in example 6.

Product weights

Raw product: 396 g

Distillate : 234 g

Product composition after filtration

Calcium: 14.5% w/w

Sulphur: 2.2% w/w

CO₂ : 13.1% w/w

TBN: 399

V₁₀₋₀ : 706 cSt

Stearic acid: 12.9% w/w

This example demonstrates that a high TBN concentrate having a lower viscosity as compared to Example 6 can be produced at a stearic acid content of 12.9% w/w based on the weight of the concentrate.

Example 8 Charge:

Sulfurized calcium alkylphenate : 230 g

Lubricating oil (100 SN) : 0 g

Calcium chloride : 3 g

Proceedings

(a) The batch was heated to 100ºC, stearic acid (99 g) was then added and the mixture was stirred for 15 minutes,

(b) 2-Ethylhexanol (190 g) was added at 100 to 110 °C.

(c) Lime (66 g) was added at 110ºC/2in Hg under vacuum.

(d) The mixture was heated to 145ºC/10in Hg and ethylene glycol (32 g) was added over 20 minutes.

(e) The mixture was kept at 145ºC/10 in Hg for 5 minutes,

(f) Carbon dioxide (66 g) was added at 145ºC,

(g) the product was stripped at 200ºC/30 in Hg and

(h) the product was filtered. The filtration rate was low.

Product weights

Raw product: 398 g

Distillate : 209 g

Product composition after filtration

Calcium: 11.95% w/w

Sulphur: 1.65% w/w

CO₂ : 11.6% w/w

TBN: 349

V₁₀₋₀ : 100 cSt

V₄₀ : 974 cSt

Stearic acid: 24.9% w/w

This example shows that it is possible to obtain a concentrate with a high TBN and a low viscosity with a stearic acid content of 24.9% w/w.

Comparison test 1 Charge:

As in example 3.

Procedure:

As in Example 3 except that the addition of ethylene glycol in step (d) was omitted.

Product weights

Raw product: 382 g Distillate: 200 g

Product composition after filtration

Calcium: 8.4% w/w

Sulphur: 2.3% w/w

CO₂ : 4.4% w/w

TBN: 239

V₁₀₋₀ : 41 cSt

The filtration rate in step (h) was low.

This is not an example according to the present invention and is included to demonstrate that the presence of component (c) is essential to the performance of the process of the invention.

Example 9 Charge:

As in example 3.

Procedure:

As in Example 3 except that the ethylene glycol addition in step (d) was reduced from 32 g to 16 g.

Product weights

Raw product: 399 g

Distillate : 225 g

Product composition after filtration

Calcium: 13.7% w/w

Sulphur: 2.0% w/w

CO₂ : 13.5% w/w

TBN: 395

V₁₀₋₀ : 182 cSt

Stearic acid: 15.8% w/w

The filtration rate in step (h) was low.

This example shows that the addition of ethylene glycol can be reduced by 50% compared to Example 3.

Example 10 Charge:

Sulfurized calcium alkylphenate : 230 g

Lubricating oil (100 SN) : 26 g

Ammonium chloride : 4 g

Acetic acid : 2 g

Procedure:

As in Example 3 except that in step (b) methyl diglycol (130 g) was added instead of 2-ethylhexanol (190 g) and that in step (d) the addition of ethylene glycol was omitted.

Product weights

Raw product: 390 g

Distillate : 166 g

Product composition after filtration

Calcium: 14.1% w/w

Sulphur: 2.0% w/w

CO₂ : 14.2% w/w

TBN: 398

V₁₀₋₀ : 210 cSt

V₄₀ : 3821 cSt

VI : 170

The filtration rate in step (h) was high.

This example shows that methyldiglycol is effective as component (C).

Example 11 Charge:

As in example 3.

Procedure:

As in Example 3 except that in step (d) the pressure was 270 mm Hg.

Product weights

Raw product: 402 g

Distillate : 238 g

Product composition after filtration

Calcium: 14.0% w/w

Sulphur: 1.9% w/w

CO₂ : 14.4% w/w

TBN: 392

V₁₀₋₀ : 288 cSt

Stearic acid: 15.7% w/w

Stearic acid: 16.2% w/w

Example 12 Charge:

As in example 3.

Procedure:

As in Example 3 except that 40 g of 2-ethylhexanol were used instead of 190 g.

Product weights

Raw product: 399 g

Distillate : 90 g

Product composition after filtration

Calcium: 13.9% w/w

Sulphur: 1.9% w/w

CO₂ : 12.1% w/w

TBN: 408

V₁₀₋₀ : 387 cSt

V₄₀ : 7980 cSt

VI : 193

Stearic acid: 15.8 w/w

Example 13 Charge:

Sulfurized calcium alkylphenate: 230 g

Stearic acid: 63 g

Calcium chloride : 4 g

linear C₁₈-alpha-olefin : 26 g

2-Ethylhexanol : 90 g

Procedure:

(a) The mixture was heated to 145-165ºC/700 mm Hg while ethylene glycol (32 g) was added,

(b) the mixture was kept at 165ºC/700 mm Hg for 30 minutes,

(c) CO₂(38 g) was added at 165ºC/1 bar,

(d) the mixture was cooled to 120ºC and 2-ethylhexanol (100 g) was added,

(e) Lime (66 g) was added,

(f) the mixture was kept at 165ºC/700 mg Hg for 5 minutes,

(g) Carbon dioxide (66 g) was added,

(h) the solvent was recovered by stripping at 200ºC/10 mm Hg,

(i) the product was filtered.

Product weights

Raw product: 385 g

Distillate : 256 g

Product composition after filtration:

Calcium: 14.8% w/w

Sulphur: 1.9% w/w

VO₂ : 13.4% w/w

TBN: 424

V₁₀₋₀ : 583 cSt

V₄₀ : 13,080 cSt

VI : 209

Stearic acid: 16.4% w/w

The filtration rate in step (i) was high.

This example shows that a lubricating oil can be replaced by an α-olefin having a long carbon chain (in this case C₁₈).

Example 14 Charge:

Sulfurized calcium alkylphenate (250 TBN) obtained from a mixture of C₁₂/C₂₂/C₂₄ alkylphenols: 233.5 g

Lubricating oil (SN 100) : 26 g

Calcium chloride : 3 g

Proceedings

(a) The mixture was heated to 100ºC, stearic acid (63 g) was added and the mixture was stirred for 15 minutes,

(b) 2-Ethylhexylsnol (194 g) was added at 100-110ºC,

(c) Lime (66 g) was added at 110ºC/2 in Kg in vacuum,

(d) the mixture was heated to 145ºC/10 in Kg and ethylene glycol (32 g) was added over 20 minutes,

(e) the mixture was kept at 145ºC/10 in Kg for 5 minutes,

(f) Carbon dioxide (66 g) was added,

(g) the product was stripped at 200ºC/30 in Kg,

(h) the product was filtered.

Product weights

Raw product: 385 g

Distillate : 250 g

Product composition after filtration:

Calcium: 14.0% w/w

Sulphur: 1.84% w/w

CO₂ : 12.9% w/w

TBN: 401

V₁₀₋₀ : 381 cSt

V₄₀ : 8.385 cSt

VI : 186 Stearic acid: 16.4% w/w

This example shows that sulfurized calcium alkylphenates derived from a mixture of C12/C22/C24 alkylphenols can be improved.

Example 15 Charge:

Sulfurized calcium alkylphenate: 181 g

Lubricating oil (SN 100) : 50 g

Calcium chloride : 4 g

Baps-Top fatty acid : 62 g

2-Ethylhexanol : 190 g

Proceedings

(a) The mixture was heated to 120ºC,

(b) Lime (43 g) was added at 120ºC/2 in Kg in vacuum,

(c) Ethylene glycol (32 g) was added at 145-165ºC/2 in Kg,

(d) the mixture was kept at 165ºC/2 in Kg for one hour,

(d) Carbon dioxide (44 g) was added,

(f) the mixture was cooled to 130ºC and lime (29 g) was added at 130ºC/2 in Hg,

(g) the mixture was kept at 165ºC/2 in Kg for one hour,

(h) Lime (22 g) was added at 165ºC,

(i) the product was stripped at 200ºC/30 in Kg,

(j) the product was filtered.

Product weights

Raw product: 382 g

Distillate: 230 g

Product composition after filtration:

Calcium : 14.0% w/w Sulfur : 1.8% w/w CO₂ : 12.3% w/w TBN : 374 V₁₀�0 : 176 cSt V₄₀ : 2.826 cSt VI : 172 Carboxylic acid content: 16.2% w/w

This example shows that Beps-Top fatty acid can be used in the process of the invention.

Example 16 Charge:

Sulfurized Galcium Alkylphenate: 230 g

Lubricating oil (SN 100) : 26 g

Calcium chloride : 3g

Proceedings

As in Example 2 except that in step (a) tall oil fatty acid (63 g) was used instead of stearic acid (63 g).

Product weights

Raw product: 380 g

Distillate : 223 g

Product composition after filtration:

Calcium: 14.0% w/w

Sulphur: 2.09% w/w

CO₂ : 9.7% w/w

TBN: 380

V₁₀₋₀ : 263 cSt

Carboxylic acid content: 16.6% w/w based on the weight of the product.

This example shows that tall oil fatty acid can be used in the process of the invention.

Example 17 Charge:

As in example 16.

Procedure:

As in Example 16 except that instead of tall oil fatty acid (63 g) a mixture of 52 g polyisobutene succinic anhydride (PIBSA) in lubricating oil SN 100 (TBN: 60 mg KOK/g) and stearic acid (47 g) was used.

Product weights

Raw product: 390 g

Distillate : 219 g

Product composition after filtration:

Calcium: 13.1% w/w

Sulphur: 1.8% w/w

CO₂ : 121.5% w/w

TBN: 360

V₁₀₋₀ : 416 cSt

V₄₀ : 12,690 cSt

VI : 164

Carboxylic acid content: 12.1% w/w) based on the weight

Anhydride content : 7.2 % w/w of product

This example shows that the carboxylic acid in the process of the invention can be partially replaced by PIBSA.

Example 18 Charge:

As in example 16.

Procedure:

As in Example 16 except that behenic acid (63 g) was used instead of tall oil fatty acid (63 g).

Product weights

Raw product: 402 g

Distillate : 247 g

Product composition after filtration:

Calcium: 12.4% w/w

Sulphur: 1.9% w/w

CO₂ : 11.4% w/w

TBN: 354

V₁₀₋₀ : 141 cSt

Behenic acid: 15.7% w/w

This example shows that behenic acid can be used as a carboxylic acid in the process of the invention.

Example 19 Charge:

As in Example 15 except that palmitic acid (56.2 g) was used instead of rapeseed fatty acid (62 g).

Procedure:

As in Example 15 except that steps (f), (g) and (h) are omitted.

Product weights

Raw product: 312 g

Distillate : 222 g

Product composition after filtration:

Calcium: 11.7% w/w

Sulphur: 1.9% w/w

CO₂ : 8.2% w/w

TBN: 332

V100 : 70 cS

Behenic acid : 831 cSt

VI : 156

Palmitic acid: 18.0% w/w

This example shows that palmitic acid can be used in the process of the invention.

Example 20 Charge:

As in example 15.

Procedure:

As in Example 15 except that steps (f), (g) and (h) are omitted.

Product weights

Raw product: 334 g

Distillate : 234 g

Product composition after filtration:

Calcium: 11.8% w/w

Sulphur: 1.8% w/w

CO₂ : 10.9% w/w

TBN: 321

V₁₀₋₀ : 168 cSt

V₄₀ : 1.009 cSt

VI : 286

Carboxylic acid content: 18.6% w/w based on the weight of the product.

Comparison test 2 Charge:

Sulfurized calcium alkylphenate: 230 g

Lubricating oil : 26 g

Calcium chloride : 3 g

Procedure:

(a) The mixture was heated to 100ºC and 2-ethylhexanol (190 g) was added,

(b) Acetic acid (14 g) was added,

(c) the mixture became thick and heterogeneous and took on a green color. Stirring was ineffective. The reaction was stopped.

This experiment is not an example according to the present invention and is included to demonstrate that lower carboxylic acids, in this case acetic acid, cannot be used in the process of the invention.

Example 21 Charge:

As in Example 16 except that instead of the commercially available sulfurized calcium alkylphenate, a commercially available non-carbonated sulfurized calcium C12 alkylphenate (TBN:145) was used.

Procedure:

As in Example 16 except that in step (c) the amount of lime was increased from 66 g to 83 g and that in step (f) the amount of carbon dioxide was increased from 66 g to 83 g.

Product weights

Raw product: 421 g

Distillate : 246 g

Product composition after filtration:

Calcium: 13.7% w/w

Sulphur: 1.9% w/w

CO₂ : 10.3% w/w

TBN: 383

V₁₀₋₀ : 137 cSt

V₄₀ : 2.119 cSt

VI : 163

Carboxylic acid: 15% w/w

This example demonstrates that a sulfurized, non-carbonated calcium alkylphenate with a low initial TBN can be used in the process of the invention.

Example 22 Charge:

Carbonated sulfurized Galcium alkylphenate (TBN: 150) : 253 g

Stearic acid: 40 g

2-Ethylhexanol : 90 g

Calcium chloride : 4 g

Procedure:

(a) The mixture was heated to 145 to 165°C/700 mm Hg while ethylene glycol (32 g) was added,

(b) the mixture was kept at 165ºC/700 mm Hg for 30 minutes,

(c) Carbon dioxide (38 g) was added at 165ºC/1 bar,

(d) the mixture was cooled to 120ºC and 2-ethylhexanol (100 g) and lime (76 g) were added,

(e) the mixture was kept at 165ºC/700 mm Hg for 60 minutes,

(f) Carbon dioxide (82 g) was added at 165ºC/1 bar,

(g) the solvent was recovered at 200ºC/10 mm Hg and

(h) the product was filtered.

Product weights

Product weight: 390 g

Product composition after filtration:

Calcium: 14.4% w/w

Sulphur: 2.3% w/w

CO₂ : 11.6% w/w

TBN: 402

V₁₀₋₀ : 674 cSt

Stearic acid: 10.3% w/w

This example shows that a sulfurized calcium alkylphenate with a low TBN (150) can be upgraded to a product with a high TBN.

Example 23 Charge:

As in Example 14 except that instead of the sulfurized calcium alkylphenate derived from a mixture of alkylphenols, the commercially available sulfurized calcium alkylphenate derived from C12 alkylphenol (TBN: 250) was used.

Procedure:

As in Example 14 except that in step (b) isoheptanol (190 g) was used instead of 2-ethylhexanol (194 g) and that in step (d) the ethylene glycol was added rapidly (within one minute).

Product weights

Raw product: 402 g

Distillate : 239 g

Product composition after filtration:

Calcium : 13.9% w/w Sulfur : 1.9% w/w CO₂ : 12.0% w/w TBN : 391 V₁₀�0 : 313 cSt V₄₀ : 6,700 cSt VI : 177 Stearic acid : 15.7% w/w

The filtration rate was high.

This example shows that isoheptanol can be used as a solvent in the process of the invention.

Claims (32)

1. Process for the preparation of an additive concentrate suitable for incorporation into a finished lubricating oil composition, which additive concentrate: (a) a lubricating oil, (b) a lubricating oil soluble sulfurized alkaline earth metal hydrocarbylphenate which is prepared by incorporating more than 2 to 35% by weight, based on the weight of the concentrate, of either (i) at least one carboxylic acid having the formula: wherein R represents a (C₁₀-C₂₄)alkyl or alkenyl group and R¹ represents either hydrogen, a (C₁-C₄)alkyl group or a -CH₂-COOH group, or an anhydride or ester thereof or (ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an anhydride or ester thereof, wherein the concentrate has a TBN of more than 300 and a viscosity at 100ºC of less than 1000 mm² S⊃min;¹ (cSt), which process comprises reacting (A) a sulfurized alkaline earth hydrocarbyl phenate having a lower TBN than the finished additive concentrate, (B) an alkaline earth metal base which is either added in its entirety to the original reactants or is added in a portion to the original reactants and the remainder is added in one or more parts in a subsequent step or steps in the reaction, (C) either a polyhydric alcohol having 2 to 4 carbon atoms, a di- or tri(C₂-C₄)glycol, an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether, (D) a lubricating oil, (E) Carbon dioxide added subsequently to the addition or to each addition of component (B) and sufficient (F) to contain from more than two to 35% by weight, based on the weight of the concentrate, of either (i) at least one carboxylic acid having the formula: wherein R represents a (C₁₀-C₂₄)alkyl or alkenyl group and R¹ represents either hydrogen, a (C₁-C₄)alkyl group or a -CH₂-COOH group, or an anhydride or ester thereof or (ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an anhydride or ester thereof, at elevated temperature, wherein the weight ratios of the components (A) to (F) are such that a concentrate having a TBN of more than 300 is produced. 2. A process according to claim 1, wherein the lubricating oil is 10 to 90 wt.% of the concentrate. 3. A process according to claim 1 or 2, wherein the alkaline earth metal of the lubricating oil soluble sulfurized alkaline earth metal hydrocarbylphenate is calcium, magnesium or barium. 4. A process according to claim 3, wherein the alkaline earth metal is calcium. 5. A process according to any preceding claim, wherein the hydrocarbyl phenate moiety of the oil-soluble hydrocarbyl phenate is derived from at least one alkylphenol, the alkyl group or groups of the alkylphenol or alkylphenols containing from 9 to 28 carbon atoms. 6. The process of claim 5 wherein the hydrocarbyl phenate moiety is derived from a C₁₂-alkylphenol obtained by alkylating phenol with a propylene tetramer. 7. A process according to any one of the preceding claims, wherein at least one carboxylic acid having the formula (I) is incorporated, wherein R represents an unbranched alkyl or alkenyl group. 8. A process according to claim 7, wherein in the carboxylic acid of formula (I) R represents a straight chain (C₁₀-C₂₄)alkyl group and R¹ is hydrogen. 9. A process according to any one of claims 1 to 6, wherein a mixture of carboxylic acids of formula (I) is incorporated, which mixture is a commercial grade containing a range of acids including both saturated and unsaturated acids. 10. A process according to claim 8, wherein steanic acid is incorporated. 11. A process according to any one of claims 1 to 6, wherein a di- or polycarboxylic acid having 36 to 100 carbon atoms or an anhydride thereof is incorporated. 12. The process of claim 11 wherein either a polyisobutenesuccinic acid or a polyisobutenesuccinic acid hydride is incorporated. 13. A process according to any one of the preceding claims, wherein (i) or (ii) is incorporated in component (b) in an amount of more than 10 to 35% by weight, based on the weight of the concentrate. 14. A process according to claim 13, wherein (i) or (ii) is incorporated in component (b) in an amount in the range of 12 to 20% by weight based on the weight of the concentrate. 15. A process according to any preceding claim, wherein the TBN of the concentrate is greater than 350. 16. The process of claim 15, wherein the TBN of the concentrate is greater than 400. 17. A process according to any preceding claim, wherein the viscosity of the concentrate at 100°C is less than 750 (cSt). 18. A process according to claim 17, wherein the viscosity of the concentrate at 100°C is less than 600 mm2·s⁻¹ (cSt). 19. A process according to any preceding claim, wherein component (B) is lime. 20. A process according to any one of the preceding claims, wherein the weight ratio of component (B) to component (A) is in the range of 0.2 to 5. 21. A process according to any one of the preceding claims, wherein component (C) is ethylene glycol. 22. A process according to any one of claims 1 to 20, wherein component (C) is methyl diglycol. 23. A process according to any one of the preceding claims, wherein the carbon dioxide (component E) is added following a single addition of component (B) at the end of the reaction between components (A) to (D) and (F). 24. A process according to any preceding claim, wherein a diluent is present. 25. A process according to any one of the preceding claims, wherein sulfur is added to the reaction mixture in addition to the sulfur already present due to component (A). 26. A process according to any one of the preceding claims, wherein the reaction is carried out in the presence of a catalyst. 27. The process of claim 26, wherein the catalyst is an inorganic halide. 28. The process of claim 27 wherein the catalyst is calcium chloride. 29. A finished lubricating oil composition, said composition comprising a lubricating oil and a sufficient amount of the additive concentrate prepared by the process of any preceding claim to provide a TBN in the range of 0.5 to 120. 30. A finished lubricating oil composition according to claim 29, wherein the lubricating oil is a marine lubricating oil and a sufficient amount of the additive concentrate is present to provide a TBN in the range of 9 to 100. 31. A finished lubricating oil composition according to claim 29, wherein the lubricating oil is an automotive engine lubricating oil and a sufficient amount of the additive concentrate is present to provide a TBN in the range of 4 to 20. 32. Additive concentrate suitable for incorporation into a finished lubricating oil, which concentrate is obtained by reacting (A) a sulfurized alkaline earth metal hydrocarbyl phenate having a lower TBN than the finished additive concentrate, (B) an alkaline earth metal base which is either added in its entirety to the original reactants or is added in a portion to the original reactants and the remainder is added in one or more parts in a subsequent step or steps in the reaction, (C) either a polyhydric alcohol having 2 to 4 carbon atoms, a di- or tri(C₂-C₄)glycol, an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether, (D) a lubricating oil, (E) Carbon dioxide added subsequently to the addition or to each addition of component (B) and sufficient (F) to contain from more than two to 35% by weight, based on the weight of the concentrate, of either (i) a carboxylic acid of formula (I) or an acid anhydride or ester thereof or of (ii) a di- or polycarboxylic acid having 36 to 100 carbon atoms or an acid anhydride or ester thereof, obtainable in the presence of a catalyst at elevated temperature, wherein the weight ratio of components (A) to (F) is such as to produce a concentrate having a TBN of more than 300 and a viscosity at 100°C of less than 1000 mm² s⁻¹ (cSt).