WO1995016011A1

WO1995016011A1 - High tbn alkaline earth metal hydrocarbyl phenate concentrates, their production and finished lubricating oil compositions containing them

Info

Publication number: WO1995016011A1
Application number: PCT/GB1994/002602
Authority: WO
Inventors: Stephen James Cook; Paul Kristian Robinson
Original assignee: BP Chemicals Additives Ltd
Current assignee: Lubrizol Adibis Holdings UK Ltd
Priority date: 1993-12-08
Filing date: 1994-11-29
Publication date: 1995-06-15
Anticipated expiration: 1996-06-08
Also published as: JPH08506617A; EP0682688A1; GB9325132D0

Abstract

An additive concentrate suitable for incorporation into a finished lubricating oil composition comprises: (A) a lubricating oil, and (B) a lubricating oil soluble alkaline earth metal hydrocarbyl phenate modified by reaction to incorporate: (a) from greater than 2 to less than 40 % by weight based on the weight of the concentrate of either (i) at least one carboxylic acid having formula (I), wherein R is a C10 to C24 alkyl or alkenyl group and R1 is hydrogen, a C¿1? to C4 alkyl group or a -CH2COOH group, or an anhydride or ester thereof, or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride or ester thereof, (b) boron in an amount from 0.01 to 10 % by weight, and (c) carbon dioxide, the concentrate having a TBN greater than 300.

Description

HIGH TBN ALKALINE EARTH METAL HYDROCARBYL PHENATE CONCENTRATES, THEIR PRODUCTION AND FINISHED LUBRICATING OIL COMPOSITIONS CONTAINING THEM

The present invention relates in general to lubricating oil additive concentrates having a total base number (TBN) greater than 300 containing an alkaline earth metal hydrocarbyl phenate, a process for their production and finished lubricating oil compositions containing the additive concentrate.

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.

Compounds generally employed to neutralise the acidic materials and disperse sludge within the lubricating oil include 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.

Alkaline earth metal sulphurised hydrocarbyl phenate-containing compositions having a high TBN (total base number as measured in mg KOH/g by the method of ASTM D2896), that is a TBN greater than 300, typically greater than 350, and a viscosity measured at 100°C of less than 1,000 cSt, preferably less than 750 cSt, more preferably less than 500 cSt, and processes for producing them are known. Thus, our EP-A-271 262 discloses an additive concentrate suitable for incorporation into a finished lubricating oil composition, the additive concentrate comprisin :- (a) a lubricating oil,

(b) a lubricating oil soluble sulphurised or non-sulphurised alkaline earth metal hydrocarbyl phenate modified by incorporation of from greater than 2 to less than 40% by weight based on the weight of the composition of either (i) at least one carboxylic acid having the formula:-

R - CH - COOH (I)

Rl wherein R is a C^₀ ^to 24 ^alky! or alkenyl group and R¹ is either hydrogen, a C- 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. The additive concentrate can be prepared by reacting at elevated temperature (1) a hydrocarbyl phenol and sulphur, (2) an alkaline earth metal base, (3) a solvent such as a polyhydric alcohol, (4) a lubricating oil, (5) carbon dioxide, and (6) sufficient to provide from greater than 2 to less than 40% by weight based on the weight of the concentrate of either (i) a carboxylic acid having the formula (I) or an acid anhydride or ester thereof or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an acid anhydride or ester thereof. Our EP-A-273588 also discloses an alkaline earth metal sulphurised hydrocarbyl phenate- containing composition having a high TBN. The composition can be prepared by reacting at elevated temperature (A) a sulphurised alkaline earth metal hydrocarbyl phenate having a TBN less than that of the final additive concentrate, (B) an alkaline earth metal base added in either a single addition or in a plurality of additions at intermediate points during the reaction, (C) either a polyhydric alcohol having from 2 to 4 carbon atoms, a di- or tri- (C2 to C4) glycol, an alkylene glycol alkyl ether or a polyalkylene glycol alkyl ether, (D) a lubricating oil, (E) carbon dioxide added subsequent to the, or each, addition or component (B), and (F) sufficient to provide from greater than 2 to 35% by weight based on the weight of the concentrate of either (i) a carboxylic acid having the formula (I) or an acid anhydride, or ester thereof or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an acid anhydride, or ester thereof, the weight ratio of components (A) to (F) being such as to produce a concentrate having a TBN greater than 300. Thus the process of EP-A-271262 is one for the production of a high TBN alkaline earth metal containing composition from the precursors of a sulphurised hydrocarbyl phenol ie a hydrocarbyl phenol and elemental sulphur (first-intent process), whereas the process of EP-A-273588 is a process for the production of a high TBN alkaline earth metal containing composition by upgrading a pre-formed alkaline earth metal sulphurised hydrocarbyl phenate (upgrade process) .

The high TBN phenate-containing concentrates described hereinbefore have one or more of the following properties:- capability of neutralising acidic materials, capability of dispersing sludge, antioxidancy and improved compatability with other lubricating oil additives, for example highly overbased sulphonates. A problem to be overcome is that of extending the range of properties of the phenate containing concentrates by, for example, improving the anti-wear properties of the detergents. We have found that a solution to the problem is to further modify the phenate with boron.

It is known from, for example, EP-B-0416757 that boron can advantageously be incorporated into alkaline earth metal hydrocarbyl phenates. Thus, EP-B-0416757 discloses a process for producing an alkaline earth metal borate dispersion, comprising the steps of:

(1) reacting a mixture of

(A) 100 parts by weight of at least one oil-soluble alkaline earth metal salt selected from the group consisting of an oil soluble neutral alkaline earth metal salicylate, an oil-soluble neutral alkaline earth metal phenolate and an oil-soluble neutral alkaline earth metal catecholate with

(B) 10 to 20 parts by weight of an alkaline earth metal hydroxide or oxide, (C) 0.5 to 6.5 moles, per mole of component (B), of a boric acid or anhydride,

(D) 20 to 1000 parts by weight of an alkanol of 1 to 4 carbon atoms,

(E) 1 to 40 parts by weight of water, and (F) 40 to 1000 parts by weight of a diluent at 20 to 120°C, and

(2) removing the water and optinally part of the alkanol and/or the diluent from the reaction mixture by heating it to 100 to 200°C.

The subject matter of EP-B-0416757 is published in greater detail in the April 1983 issue of Lubrication Engineering, 4.9, 4, 263-268 in a paper entitled "Calcium Borate Overbased Metallic Detergent" by Kiyoshi Inone. It is apparent that the disclosure is only concerned with overbased detergents in which the alkaline reservoir is exclusively composed of alkaline earth metal borates in contrast to alkaline earth metal carbonates or mixed borates/carbonates. To this end their preparation begins with the neutral salts and there is no subsequent carbonation step. Moreover, there is no disclosure of materials having a high Total Base Number, the highest TBN mentioned being 207 mg KOH/g for the phenates and 200 mg KOH/g for the salicylate. Such materials are to be distinguished from the products of the present invention which have TBN's greater than 300 mg KOH/g, have a mixed borate/carbonate alkaline reservoir, are prepared by methods incorporating a carbonation step and can be prepared in the substantial absence of water. Accordingly in one aspect the present invention provides an overbased additive concentrate suitable for incorporation into a finished lubricating oil composition, the additive concentrate comprising:-

(A) a lubricating oil, and (B) a lubricating oil soluble alkaline earth metal hydrocarbyl phenate modified by reaction to incorporate:-

(a) from greater 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 is a C₁₀ to C₂4 alkyl or alkenyl group and R¹ is hydrogen, a C_j to C₄ alkyl group or a -CH2-COOH group, or an anhydride or ester thereof, or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride or ester thereof,

(b) boron in an amount from 0.01 to 10% by weight, and

(c) carbon dioxide, the concentrate having a TBN greater than 300.

The TBN of the concentrate is greater than 300, preferably greater than 350, more preferably greater than 400.

Suitably the concentrate has a viscosity of less than lOOOcSt, preferably less than 750cSt, more preferably less than 500cSt. The lubricating oil [component (A)] is suitably an animal oil, a vegetable oil or a mineral oil, such as a naphthenic base, paraffin base or mixed base oil. Suitably the lubricating oil is a petroleum- derived lubricating oil. Solvent neutral oils are particularly suitable. Alternatively, the lubricating oil may be a synthetic lubricating oil. Suitable synthetic lubricating oils include synthetic ester lubricating oils, which oils include diesters such as di-octyl adipate, di-octyl sebacate and tridecyladipate,or polymeric hydrocarbon lubricating oils, for example liquid polyisobutenes and poly-alpha olefins. The lubricating oil may suitably comprise from 10 to 90%, typically from 10 to 70%, by weight of the composition.

Component (B) is a lubricating oil soluble alkaline earth metal hydrocarbyl phenate modified by reaction to incorporate (a), (b) and (c). The alkaline earth metal hydrocarbyl phenates may be sulphurised or non-sulphurised, preferably sulphurised. Suitably the alkaline earth metal may be strontium, barium, calcium or magnesium, preferably calcium or barium, more preferably calcium. Suitably the alkaline earth metal may be present in an amount in the range from 10 to 20% by weight based on the weight of the composition. The hydrocarbyl phenate moiety of the alkaline earth metal hydrocarbyl phenate is preferably derived from at least one alkyl phenol. The alkyl group of the alkyl phenol may be straight-chain or branched- chain or a mixture thereof. Suitable alkyl groups contain from 4 to 50, preferably from 9 to 28 carbon atoms. A particularly suitable alkyl phenol is the C₁₂- alkyl phenol obtained by alkylating phenol with propylene tetramer. The phenol may be mono- or poly- alkylated. The alkaline earth metal phenate is modified by incorporation of (a),(b) and (c). As regards (a) this may be either (i) or (ii). As regards (i) this is at least one carboxylic acid having the formula (I), or an anhydride or ester thereof. Preferably R in the formula (I) is an unbranched alkyl or alkenyl group. Preferred acids of formula (I) are those wherein R is a C^Q to C24, more preferably C₁₈ to C₂4 straight-chain 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 lignoceric acid. Examples of suitable unsaturated acids of formula (I) 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 acid. 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 the acid anhydride, or the ester derivatives of the acid, preferably the acid anhydride. It is preferred however to use a carboxylic acid or a mixture of carboxylic acids. A preferred carboxylic acid of formula (I) is stearic acid.

Instead of, or in addition to (i), the alkaline earth metal hydrocarbyl phenate may be modified by incorporation of (ii), which is a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an acid anhydride or ester derivative thereof, preferably an acid anhydride thereof. Preferably (ii) is a polyisobutene succinic acid or a polyisobutene succinic anhydride.

It is preferred to incorporate component (B) (a) and in particular stearic acid. Preferably the carboxylic acid(s) having the formula (I), the di-or polycarboxylic acid, or the acid anhydride or ester therof is incorporated in an amount 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 greater than 10% of the carboxylic acid or derivative thereof is generally a relatively lower concentrate viscosity.

Suitably sulphur may be present in the composition in an amount in the range from 1 to 6, preferably from 1.5 to 3% by weight based on the weight of the composition. In addition to incorporating (a) the phenate is modified by incorporation of boron (b) . This may suitably be present in the form of the borate salt. Boron is present in an amount in the range from 0.01 to 10% by weight, preferably from 0.25 to 5% by weight based on the weight of the concentrate composition. In addition to incorporating (a) and (b) the phenate is further modified by incorporating carbon dioxide (c).

Suitably carbon dioxide may be present in the composition in an amount in the range from 5 to 20, preferably from 9 to 15% by weight based on the weight of the composition. In a preferred embodiment the present invention provides an overbased additive concentrate suitable for incorporation into a finished lubricating oil composition, the additive concentrate comprising:-

(A* ) a lubricating oil, and (B') a lubricating oil soluble alkaline earth metal hydrocarbyl phenate, modified before overbasing by reaction with an aldehyde and further modified by reaction to incorporate:-

R-CH-COOH

wherein R is a C-^_Q to C24 alkyl or alkenyl group and R^ is hydrogen, a C^ to C4 alkyl group or a -CH2-COOH group, or an anhydride or ester thereof, or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride or ester thereof,

(b) boron in an amount of from 0.01 to 10% by weight, (c) carbon dioxide wherein the amount of lubricating oil (A' ) in the additive concentrate is such that the ratio of the weight of the additive concentrate to the weight of the hydrocarbyl phenate, or its precursors, from which the modified alkaline earth metal hydrocarbyl phenate is derived, is at least 3.0 and the concentrate having a TBN greater than 300.

The ratio of the weight of the additive concentrate (Yg) to the weight of the hydrocarbyl phenate or its precursors, from which the modified alkaline earth metal hydrocarbyl phenate is derived (Xg) may be regarded as 'the scale up factor'. It is an advantage of the concentrate of the preferred embodiment that it can have a ' scale up factor' of at least 3, for example at least 5, and as high as at least 10. This is an advantage because the higher the 'scale up factor" the higher is the proportion of lubricating oil in the concentrate relative to hydrocarbyl phenol at a given high TBN and since lubricating oil is very much cheaper than hydrocarbyl phenol, the cost of the product is reduced proportionately.

Component (A*) is a lubricating oil. Suitable lubricating oils are as hereinbefore described. Component (B') of the preferred embodiment is an alkaline earth metal hydrocarbyl phenate modified before overbasing by reaction with an aldehyde and further modified by reaction to incorporate (a) from greater 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 (I) or an anhydride or ester thereof, or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride or ester thereof, (b) boron in an amount of from 0.01 to 10% by weight, and (c) carbon dioxide. As regards the further modification by reaction to incorporate (a),(b) and (c), further details are given hereinbefore. As regards modification before overbasing by reaction with an aldehyde, any aldehyde may be employed. Suitable aldehydes include formaldehyde, propionaldehyde and butyraldehyde for example. A preferred aldehyde is formaldehyde in one or other of its physical forms. It is believed, though we do not wish to be bound in any way by the theory, that reaction with the aldehyde, for example formaldehyde, by condensation with the elimination of water results in the bridging of two or more phenate molecules.

In another aspect the present invention provides a process for the production of an additive concentrate as hereinbefore described which process comprises reacting at elevated temperature:- (A") at least one compound which is (A")(i) an alkaline earth metal hydrocarbyl phenate, (A")(ii) an alkaline earth metal sulphurised hydrocarbyl phenate, (A")(iii) an alkaline earth metal hydrocarbyl phenate and a source of sulphur, (A")(iv) a hydrocarbyl phenol,

(A")(v) a sulphurised hydrocarbyl phenol and (A")(vi) a hydrocarbyl phenol and a source of sulphur, Optionally (B") an aldehyde,

(C") an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction, (D') a solvent comprising either:- (1) either:

(i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di- (C₃ or C₄) glycol,

(iii) a tri- (C2 - C₄) glycol, or

(iv) a mono- or poly-alkylene glycol alkyl ether of the formula:- fOR^-JxOR² (II) wherein in the formula (II) R is a C± to C₆ alkyl group, R¹ is an alkylene group, R² is hydrogen or a C to C₆ alkyl group and x is an integer of from 1 to 6, either alone or in combination with either (2) a hydrocarbon solvent or (3) either (a) water, (b) a C to C_2Q monohydric alcohol, (c) a ketone containing up to 20 carbon atoms, (d) a carboxylic acid ester containing up to 10 carbon atoms or (e) an aliphatic, alicyclic or aromatic ether containing up to 20 carbon atoms or, (4) a C to C₄ monohydric alcohol in combination with a hydrocarbon solvent (2), (E") a lubricating oil,

(F") carbon dioxide added subsequent to each addition of component

(C"), (G") either (i) a di- or a polycarboxylic acid containing from 36 to 100 carbon atoms or (ii) a carboxylic acid of the formula (I):- R - CH - COOH (I)

I

Rl wherein R is a

to C₂4 alkyl or alkenyl group and R is hydrogen, a C^ to C alkyl group or a -CH2COOH group, or an anhydride or ester of either (i) or (ii) and optionally (H") a catalyst for the reaction with (F"), and (I") a source of boron.

As regards component (A"), the hydrocarbyl substituent or substituents of the compounds (A")(i) - (vi) may suitably be an alkyl or alkenyl group, preferably a C-^-C^ alkyl group. Preferably, the hydrocarbyl group is a dodecyl group derived from propylene tetramer. The alkaline earth metal is preferably either strontium, calcium, magnesium or barium, more preferably calcium or barium, most preferably calcium. The amount of sulphur in (A")(ii) and (A")(v), is suitably greater than 1%, preferably at least 4% by weight, typically in the range from 4 to 12% by weight In order to achieve the high 'scale-up factor" concentrates of the preferred embodiment in the absence of aldehyde it is essential for the sulphur level in the components (A") (ii) and (A") (v) or their precursors to be greater than 4% by weight. A prefered component (A") is an overbased alkaline earth metal sulphurised hydrocarbyl phenate, for example one having a TBN in the range from about 50 to about 250, typically from about 100 to about 200. The compounds (A")(i) - (vi) and their preparation are well known in the art. Many are commercially available.

As regards optional component (B"), this is an aldehyde. As the aldehyde there may be used formaldehyde, butyraldehyde, propionaldehyde, dodecylaldehydes and higher alkyl aldehydes. It is preferred to use formaldehyde. Formaldehyde may be added in any of its physical forms but it is preferred to use either paraformaldehyde or aqueous formaldehyde (formalin), of which formalin is more preferred. The aldehyde may suitably be added in an amount sufficient to react with any alkyl phenol present in (A")(i) - (vi) on at least a 1:1 basis. The reaction of (A") with (B") may suitably be accomplished at elevated temperature, suitably in the range from 30 to 120°C, typically from 50 to 100°C. For the production of the high 'scale up factor' concentrates of the preferred embodiment it is preferred that component (B") be present in the reaction mixture. For the preparation of low 'scale up factor' concentrates the participation of (B") is unnecessary.

Component (C") 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 is preferably strontium, calcium, magnesium or barium, more preferably calcium or barium, most preferably calcium. The base moiety may suitably be an oxide or a hydroxide, preferably the hydroxide. 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)_/ preferably in the form of slaked lime. As regards the amount of component (C") to be added, this should be sufficient to achieve the desired TBN. The amount will be greater starting with components (A") (iv) - (A") (vi) than it will be starting with components (A") (i)-(A") (iii) by the amount required to convert (A") (iv)-(A") (vi) to (A") (i)-(A") (iii).

Component (D") is a solvent for the reactants. The solvent (D") may be either (D") (1) alone or in combination with either

(D")(2) or (D")(3), or the solvent (D") may be (D")(4) in combination with (D")(2) wherein:

(D")(l) is either (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di-(C₃ or C ) glycol, (iii) a tri- (C₂ to C₄) glycol or (iv) a mono- or poly-alkylene glycol alkyl ether of the formula:-

R(OR¹)xOR² (II) wherein in the formula (II) R is a C_j, to C₆ alkyl group, R¹ is hydrogen or a C^ to Cg alkyl group and x is an integer from 1 to 6. Suitable compounds having the formula (I) 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 (CH3OCH2CH2OCH2CH2OH) . Mixtures of glycol ethers of formula (V) 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-(C3 or C₄) glycol may suitably be dipropylene glycol, the tri- (C₂ to C₄) glycol may suitably be triethylene glycol. Preferably the component (D")(l) is either ethylene glycol or methyl diglycol. (D")(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. (D")(3) may be either (i) water, (ii) a C to C₂Q 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. (D")(4) may be a C_j_ to C₄ monohydric alcohol, preferably methanol. Preferred solvents (D") comprise ethylene glycol, a mixture of ethylene glycol and 2-ethyl hexanol and a mixture of methanol and toluene.

Component (E") is a lubricating oil. Suitable lubricating oils are described hereinbefore with reference to the concentrate composition. For the production of additive concentrates having a high 'scale up factor' the amount of lubricating oil must be such that a 'scale up factor' as hereinbefore defined of at least 3.0 is achieved.

Component (F") is carbon dioxide added subsequent to each addition of component (C"). 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.

Component (G") is either (i) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or (ii) a carboxylic acid of the formula (I), or an acid anhydride or ester of either (i) or (ii). Suitable components (G") are described hereinbefore with reference to components (B)(a)(i) and (ii) of the concentrate composition. A preferred carboxylic acid of formula (I) is stearic acid.

Optional component (H") is a catalyst. It is preferred that a catalyst be present for the achievement of higher TBN concentrates, for example TBNs greater than 350, and for the production of the higher 'scale-up factor' concentrates. The catalyst may be either an inorganic compound or an organic compound, preferably an inorganic compound. Suitable inorganic compounds include hydrogen halides, metal halides, ammonium halides, metal alkanoates, ammonium alkanoates or a mono-, di-, tri- or tetra-alkyl ammonium formate or alkanoate. As regards the metal moiety of metal halides or metal alkanoates, this is suitably either zinc, aluminium, or an alkaline earth metal, for example calcium. A preferred metal moiety is calcium. As regards the halide moiety, the chloride is preferred. The alkanoate moiety is suitably a C2 to C^g alkanoate, preferably a C to C alkanoate, for example an acetate or propionate. When a substituted ammonium compound is used, it is preferably a tetra- (C to C alkyl) ammonium compound, especially a tetramethylammonium compound such as tetramethylammonium acetate. Examples of suitable catalysts include calcium chloride, ammonium chloride, calcium acetate, ammonium acetate, zinc acetate, and tetramethylammonium acetate. Suitably the amount of catalyst employed may be up to 2.0% wt/wt. The catalyst facilitates the overbasing process and may have other benefits. Component (I") is a source of boron. As the source of boron there may suitably be used either a boric acid or an anhydride thereof. Examples thereof include orthoboric acid, metaboric acid, tetraboric acid and boric anhydride. Generally orthoboric acid is preferred. Borate salts and esters of boric acid may also be employed. The molar ratio of the source of boron to the alkaline earth metal base (Component (C")) may suitably be in the range from 0.1 to 10, for example 0.5 to 6.

As regards the order of addition of the components, some must be added before others, whereas the order of addition of other components is not critical. Thus, component (C") must be added before component (F") and when component (H") is employed it must be present during the reaction of component (F"). Desirably component (B") is present during the production of high 'scale up factor' concentrates. In this event component (A") should be reacted with (B") before reaction with the remaining components. For this reaction it is preferred to employ a catalyst. Suitable catalysts include both organic and inorganic bases. It will usually be found most convenient to use as the catalyst in the reaction of (A") with (B") an alkaline earth metal base identical with the base used as component (C"). Using as component D" both a polyhydric alcohol having 2 to 4 carbon atoms [(D")(l)(i)] eg ethylene glycol, and a C to C_2Q monohydric alcohol [(D")(3)(b) eg 2-ethyl hexanol it is very much preferred to add component [(D")(l)(i) after all the other components have been reacted and before addition of component (F"). A preferred order of addition for the production of high 'scale up factor' concentrates comprises in a first step reacting component (A") (i), (ii) or (iv) with component (B") in the presence of components (D") and (G") and a catalytic amount of component (C") and thereafter in a subsequent step or steps reacting the phenate with components (C") (I"), and finally (F"). Component (E"), the lubricating oil, may suitably be added with components (A") and (B"). Provided it is present before the addition of component (F"), the catalyst for the carbonation (component H" ) may be added at any point, suitably after completion of the first step. Suitably the elevated temperature at which the process is operated may be a temperature in the range from 15 to 200°C, preferably from 50 to 175°C. The selection of the optimum temperature within the aforesaid range will depend to a large extent on the nature of the solvent employed. At the conclusion of the reaction it is preferred to recover the concentrate as a solution in lubricating oil by separating off the solvent (D"), for example by distillation at subatmospheric pressure.

Finally, it is preferred to separate off any insoluble matter, suitably by filtration or centrifugation, preferably by filtration. According to a further aspect of the present invention, there is provided a finished lubricating oil composition which composition comprises a major proportion of a lubricating oil and a minor proportion of an additive concentrate as hereinbefore described. The amount of additive concentrate present in the finished lubricating oil will depend on the nature of the final use. Thus, for marine lubricating oils the amount of additive concentrate present may suitably be sufficient to provide a TBN of 9 to 100 and for automobile engine lubricating oils the amount may suitably be 5 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, - Q or the like, which may be incorporated into the finished lubricating oil composition either directly or through the intermediacy of the concentrate composition.

The invention will now be further illustrated by reference to the following Examples. 15 The term "AV" is used to denote the Alkalinity Value as measured by the method of ASTM D2896. The viscosity was measured by the method of ASTM D445. In the Examples and Comparison Tests which follow the abbreviation V-^oo ^-^s employed. This represents the viscosity at 100°C. 20 Example 1

Step 1 A mixture of the following ingredients (A) - (G) was reacted at 1452c/ll"Hg:-

(A) 250g of an oil soluble 250TBN calcium C₁₂-alkyl phenate,

(B) 28g lube oil,

25 (C) 76g calcium hydroxide,

(D) 69g stearic acid,

(E) 4g calcium acetate,

(F) lllg 2-ethyl hexanol, and

(G) Boric acid in an amount which is 0.4 times in moles that 30 of the ingredient (C) .

Step 2 The resultant reaction mixture was held for 5 minutes prior to addition of ingredient (H):- (H) 42g ethylene glycol Step 3 The resultant reaction mixture was cooled to 1302C/ll"Hg 35 prior to addition of ingredient (I):- (I) 72g carbon dioxide at (1 bar) Step 4 The resultant reaction mixture was heated to 2102C/28"Hg to remove the 2-ethyl hexanol and the ethylene glyol Step 5 The product was filtered. Analysis of product Ca 13.99% S 1.81% AV 385 mgKOH/g VIOO 1443 cSt B 0.8%

The 'scale up factor' was 1:1.9. Example 2

Step 1 A mixture of the following ingredients (A) - (G) was reacted at 1302C/ll"Hg:- (A) 189g of an oil soluble 150TBN calcium C₁₂-alkyl phenate,

(B) 49g lube oil,

(C) 94g calcium hydroxide,

(D) 76g stearic acid,

(E) 4g calcium acetate, (F) 150g 2-ethyl hexanol, and

(G) Boric acid in an amount which is 0.4 times in moles that of the ingredient (C) . Step 2 The resultant reaction mixture was held for 10 minutes prior to addition of ingredient (H):- (H) 42g ethylene glycol

Step 3 The resultant reaction mixture was cooled to 1302C/ll"Hg prior to addition of ingredient (I):- (I) 94g carbon dioxide 1 bar Step 4 The resultant reaction mixture was heated to 2102C/28"Hg to remove the 2-ethyl hexanol and ethylene glycol. Step 5 The product was filtered. Analysis of product Ca 13.60% S 1.84% AV 387 mgKOH/g V100 606 CSt B 0.8%

The 'scale up factor' was 1:2.4. Example 3 Step 1 A mixture of te following ingredients (A) - (D) was heated to 130°C/11 inches Hg:-

(A) 189g of an oil soluble 150 TBN calcium C₁₂ ~ alkyl phenate

(B) 53g lOOSN lubricating oil

(C) 76g stearic acid, and (D) 33g boric acid.

Step 2 The resultant reaction was held for 5 minutes at 130°/ll inches Hg and subsequently cooled to 100°C/1 bar prior to the addition of ingredients (E) - (H):-

(E) 150g 2-ethyl hexanol, (F) lOOg calcium hydroxide, and

(G) 4g calcium acetate.

Step 3 The resultant reaction mixture was heated to 130°C/11 inches Hg and held for 5 minutes prior to the addition of component

(H):- (H) 42g ethylene glycol.

Step 4 The resultant reaction mixture was held for 5 minutes at

130°C (11 inches Hg prior to the addition of ingredient (I) at

120°C/1 bar:-

(I) 94g carbon dioxide. Step 5 The resultant reaction mixture was heated at 210°C/10mm

Hg to remove ethylene glycol and 2-ethyl hexanol.

Step 6 The product was filtered.

The product weight was 478g and the distillate weight was

217g. The filtration rate was very good and the crude sediment was 4%. The 'scale-up factor' was 1:2.5.

Analysis of product

Ca 13.80%

A.V. 372 mg KOH/g

S 1.80% B 1.10% V₁₀₀ 622 cSt Example 4

The procedure of Example 3 was repeated except that in step 1 the amount of boric acid added was 16.5g. The product weight was 460g and the distillate weight was 212g. The filtration rate was good and the crude sediment was 3.6%. The 'scale-up factor' was 1:2.4. Analysis of product Ca 13.70% AV 381mg KOH/g S 1.80 B 0.50% ^v100 ^{72 cSt}- Example 5 Step 1 A mixture of the following ingredients (A) to (F) was heated to 145°C/21 inches Hg:-

(A) 58g of an oil soluble 150 TBN calcium Ci2""^a-Lkyl phenate,

(B) 171g lubricating oil

(C) 42g ethylene glycol (D) 4g paraformaldehyde

(E) 73g stearic acid, and

(F) 16.5g boric acid.

Step 2 The resultant reaction mixture was held at 145°C/21 inches Hg for 15 minutes and subsequently cooled to 100°c prior to the addition of ingredients (G) - (I):-

(G) 115g calcium hydroxide (lime), (H) 150g 2-ethyl hexanol, and

(I) 6g calcium acetate.

Step 3 The resultant reaction mixture was held at 130°C/11 inches Hg for 10 minutes prior to the addition of ingredient

(J) at 130°C/1 bar:-

(J) 60g carbon dioxide.

Step 4 The resultant reaction mixture was heated at 210°C/10 mm

Hg to remove the 2-ethyl hexanol and ethylene glycol. Step 5 The product was filtered. The product weight was 422g and the distillation weight was 211g. The filtration rate was good and the crude sediment was

3.2%. The 'scale-up factor' was 1:8.

Analysis of product Ca 13.83%

S 0.76%

B 0.59%

V₁₀₀ 192 cSt V₄₀ 2821 cSt, and

VI 185.

Example 6

A product having the following analysis was prepared by the method of the invention. Analysis of product

Calcium 13.60%

Sulphur 1.72%

Boron 0.60%

AV 389 mgKOH/g V₁₀₀ 443 cSt

Example 7

The products of Examples 3, 4 and 6 were tested in the Rotary

Bomb Oxidation Test (ASTM D2272). Also tested by way of comparison was a boron-free calcium sulphurised hydrocarbyl phenate having the following analysis:-

Ca 14.30%

S 1.77%

B 0%

AV 402 mgKOH/g V₁₀₀ 425 cSt

The times for a 25 psi drop are recorded in Table 1. It can be seen from an examination of Table 1 that the boronated products of

Examples 3 and 4 exhibited significantly improved antioxidant properties as compared with a similar non-boronated product. Example 8 The products of Examples 3, 4 and 6 were tested in the Shell Four Ball Test (ASTM D4172). Also tested by way of comparison was the boron-free calcium sulphurised hydrocarbyl phenate as described in Example 7. The scar depth in mm recorded after one hour at 40 kg load at 1200 rpm is recorded in Table 2.

From an examination of the Table it can be seen that the products of Examples 3 and 6 are better and the product of Example 4 is comparable in terms of anti-wear as compared with a similar non- boronated product. Example 9

The products of Examples 3, 4 and 6 were tested in the Roxana (FTM 719b) test. Also tested by way of comparison was the boron-free calcium sulphurised hydrocarbyl phenate as described in Example 7. The deposits recorded after 3 hours at 3502C are presented in Table 3.

From an examination of the results it can be seen that the products of Examples 3 and 6 are significantly better and the product of Example 4 is worse than a similar non-boronated product in the Roxana test. Table 1

Product Time for 25 psi drop

(minutes)

Comparison 70

3 89

4 83

6 73

Table 2

Product Scar (mm)

(40 kg; 1200 rpm; . . hour)

Comparison 0.376

3 0.351

4 0.380

6 0.350

Table 3

Product Deposit (mg) (35Q2C; 3 hours )

Comparison 700 3 534 4 1028 6 598

Claims

Claims:

1. An additive concentrate suitable for incorporation into a finished lubricating oil composition, the additive concentrate comprising:-

(A) a lubricating oil, and (B) a lubricating oil soluble alkaline earth metal hydrocarbyl phenate modified by reaction to incorporate:

(a) from greater 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:- R - CH - COOH (I)

R 'l¹ wherein R is a C^_Q ^to C24 alkyl or alkenyl group and R-'- is hydrogen, a Ci to C₄ alkyl group or a -CH₂COOH group, or an anhydride or ester thereof, or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride or ester thereof,

(b) boron in an amount from 0.01 to 10% by weight, and

(c) carbon dioxide, the concentrate having a TBN greater than 300.

2. An overbased additive concentrate suitable for incorporation into a finished lubricating oil composition, the additive concentrate comprising:-

(A') a lubricating oil, and

(B') a lubricating oil soluble alkaline earth metal hydrocarbyl phenate modified before overbasing by reaction with an aldehyde and further modified by reaction to incorporate:- (a) from greater 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:-

R - CH - COOH (I) R¹ wherein R is a C^Q to C₂4 alkyl or alkenyl group and R¹ is hydrogen, a C to C₄ alkyl group or a -CH₂-COOH group, or an anhydride or ester thereof, or (ii) a di- or polycarboxylic acid containing from 36 to

100 carbon atoms or an anhydride or ester thereof, (b) boron in an amount of from 0.01 to 10% by weight, and

(c) carbon dioxide, wherein the amount of lubricating oil (A') in the additive concentrate is such that the ratio of the weight of the additive concentrate to the weight of hydrocarbyl phenate, or its precursors, from which the modified alkaline earth metal hydrocarbyl phenate is derived, is at least 3.0 and the concentrate having a TBN greater than 300.

3. An overbased additive concentrate as claimed in either claim 1 or claim 2 having a TBN greater than 350.

4. An overbased additive concentrate as claimed in any one of the preceding claims wherein the lubricating oil is a solvent neutral oil.

5. An overbased additive concentrate as claimed in any one of the preceding claims wherein the alkaline earth metal of the lubricating oil soluble alkaline earth metal hydrocarbyl phenate [(B) or (B')] is calcium.

6. An overbased additive concentrate as claimed in any one of the preceding claims wherein the lubricating oil soluble alkaline earth metal hydrocarbyl phenate [(B) or (B')] is sulphurised.

7. An overbased additive concentrate as claimed in any one of the preceding claims wherein the lubricating oil soluble alkaline earth metal hydrocarbyl phenate [(B) or (B')] is modified by incorporation of at least one carboxylic acid having the formula (I), which acid is stearic acid.

8. An overbased additive concentrate as claimed in any one of the preceding claims wherein the lubricating oil soluble alkaline earth metal hydrocarbyl phenate [(B) or (B')] is modified by incorporation of at least one carboxylic acid having the formula (I) in an amount from greater than 10% to 35% by weight based on the weight of the concentrate.

9. An overbased additive concentrate as claimed in any one of claims 2 to 8 wherein the lubricating oil soluble alkaline earth metal hydrocarbyl phenate (B') is modified before overbasing by reaction with formaldehyde.

10. An overbased additive concentrate as claimed in any one of claims 2 to 9 wherein the ratio of the weight of the additive concentrate to the weight of the hydrocarbyl phenate, or its precursors, from which the modified alkaline earth metal hydrocarbyl phenate is derived is at least 5.

11. A process for the production of the additive concentrate as claimed in any one of claims 1 to 10 which process comprises reacting at elevated temperature:-

(A") at least one compound which is (A") (i) an alkaline earth metal hydrocarbyl phenate, (A") (ii) an alkaline earth metal sulphurised hydrocarbyl phenate, (A") (iii) an alkaline earth metal hydrocarbyl phenate and a source of sulphur, (A") (iv) hydrocarbyl phenol, (A") (v) a sulphurised hydrocarbyl phenol and (A") (vi) a hydrocarbyl phenol and a source of sulphur,

Optionally (B") an aldehyde, (C") an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction,

(D") a solvent comprising either:- (1) either: (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di- (C₃ or C ) glycol, (iii) a tri- (C2 to C4) glycol, or

(iv) a mono- or poly-alkylene glycol alkyl ether of the formula:- R (OR^-J_jj OR² (II) wherein in the formula (II) R is a C_j to Cg alkyl group, R¹ is an alkylene group, R² is hydrogen or a C^ to Cg alkyl group and x is an integer of from 1 to 6, either alone or in combination with (2) a hydrocarbon solvent or (3) either (a) water, (b) a C^ to C20 monohydric alcohol, (c) a ketone containing up to 20 carbon atoms, (d) a carboxylic acid ester containing up to 10 carbon atoms or (e) an aliphatic alicyclic or aromatic ether containing up to 20 carbon atoms, or

(4) a Ci to C4 monohydric alcohol in combination with a hydrocarbon solvent (2), (E") a lubricating oil,

(F") carbon dioxide added subsequent to each addition of component (C"),

(G") either (i) a di- or a polycarboxylic acid containing from 36 to 100 carbon atoms or (ii) a carboxylic acid of the formula (I):-

R - CH - COOH (I)

Rl wherein R is a C^Q to C₂ alkyl or alkenyl group and is hydrogen, a C^ to C₄ alkyl group or a -CH₂-COOH group, or an anhydride or ester of either (i) or (ii), optionally (H") a catalyst for the reaction with (F"), and (I") a source of boron.

12. A process as claimed in claim 11 wherein component (A") is an overbased alkaline earth metal sulphurised hydrocarbyl phenate having a TBN in the range from about 100 to about 200.

13. A process as claimed in either claim 11 or claim 12 wherein the solvent (D") comprises either ethylene glycol, a mixture of ethylene glycol and 2-ethyl hexanol, or a mixture of methanol and toluene.

14. A finished lubricating oil composition which composition comprises a major proportion of a lubricating oil and a minor proportion of the overbased additive concentrate as claimed in claims 1 to 10.