CA1085385A

CA1085385A - Production of overbased metal phenates

Info

Publication number: CA1085385A
Application number: CA252,359A
Authority: CA
Inventors: Victor C.E. Burnop
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1975-05-23
Filing date: 1976-05-12
Publication date: 1980-09-09
Also published as: JPS6018713B2; BE842131A; NL7605291A; DE2622839C2; IT1066081B; FR2311838A1; GB1551819A; DE2622839A1; NL185729B; JPS51144403A; FR2311838B1; NL185729C

Abstract

Abstract Producing overbased carbonates by hydrolysing a metal alkoxyalkoxide in the presence of a phenolic or sulphonic surfactant and carbonating the product of hydrolysis.

Description

108~385 This invention relates to a process for making detergent additives of high basicity suitable for use in lubricating oils.
There is an increasing need for detergent additives which have high basicity, and this invention is concerned with high basicity magnesium sulphurised phenates, known as overbased phenates. These compounds have been found to be particularly useful as additives in lubricating oils used in connection with high sulphur fuels, such as marine diesel fuels, since the high basicity will neutralise the acids formed by the burning of the fuel.
The use of dispersed overbased alkaline earth metal compounds such as overbased alkaline earth metal phenates and sulphonates as additives in lubricating oils is known. It has been proposed to produce overbased alkaline earth metal carbonates by carbonating a mixture of a magnesium methanolate in the presence of a surfactant such as an alkyl phenol, that may be sulphurised, or an alkylaryl sulphonate. However, one problem associated with this process is that the magnesium methanolate is sparingly soluble in methanol. An alternative process using carbonated metal alkoxy-ethanol complexes as intermediates in the preparation of such overbased additives is known from United States patents 3,150,089, 3,277,002, 3,718,859, 3,746,698 and 3,775,170 where the dispersed alkaline earth metal is a carbonate.

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These earlier processes described above require the use of a volatile hydro-carbon solvent which, although not detrimental to product quality decreases the plant capacity and also requires removal and recovery and separation of the solvent ; at the end of the reaction. Our process not only enables overbased phenates ~ D~

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to be prepared both without the need to specifically form the metal complex but in many instances it does not require a volatile hydrocarbon solvent.
A problem associated with the production of overbased metal compounds is that of the viscosity of both the reaction mixture and the final product itself.
The overbased materials consist of an alkaline earth metal compound, generally a carbonate, dispersed in the alkaline earth metal salt of the dispersing agent; the amount of dispersed alkaline earth metal being known as the overbasing amount.
Generally these overbased materials are used as detergents in lubricating oils to react with acid residues formed in the oil, thus the greater the basicity of the material the better since this allows smaller amounts of the materials to be used for a given effect in a certain lubricating oil. However, to increase basicity it is necessary to increase the dispersed alkaline earth metal content which tends to increase the viscosity of the reaction mixture leading to processing problems.
This problem is particularly marked if the alkaline earth metal is introduced in the form of the carbonated complex previously described and in order to overcome this problem it may be necessary to increase the amount of solvent used thus reducing reactor capacity and requiring solvent recovery.

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According to this invention a colloidal suspension in oil of a magneslum ; carbonate together with a dispersant is prepared by a process comprising the following steps:

(1) forming a reaction mixture comprising:

(a) a magnesium alkoxyalkoxide together with the alkoxyalcohol from which ; it is derived .'' ' " - :

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(b) a surfactant which is one or more sulphurised phenols having one or more hydrocarbyl group substituents, each substituent containing not more than 60 carbon atoms, or mixtures of said surfactants (c) a non-volatlle dlluent oil (d) at least one mole of water for every gram atom of the magne-sium present in excess of the amount of magnesium required to neutralise the surfactant

(2) hydrolysing the magnesium alkoxyalkoxide !~ lo (3) after hydrolysing introducing carbon dioxlde into the reaction mixture while at a temperature not above 100C
The magnesium alkoxyalkoxide may be prepared in situ by reacting magneslum oxide or hydroxide with an alkoxy alcohol such as ethoxy ethanol.
Alternatively the alkoxyalkoxide itself may be used as the starting ma-terial in which case we use a solution of the alkoxyalkoxide in the ; ether-alcohol which ls preferably ethoxyethanol. The alkoxyalkoxide may conveniently be prepared by dissolving magnesium in the alkoxyalcohol which is preferably ethoxyethanol since the magnesium ethoxyethoxide is l readily soluble in ethoxyethanol.
i ~ 20 The or each hydrocarbyl substituent on the sulphurised phenol pre-ferably has at least nine carbon atoms. Although the hydrocarbyl sub-stituent can be an alkenyl, alkynl, aryl, aralkyl or alkaryl group, lt is preferred that it should be an alkyl group and especially one con-'~ taining 9 to 15 carbon atoms since compounds in which the alkyl group ~ contains less than 9 carbon atoms having limited solubility in oil.
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; The sulphurised phenol may have other substituents e.g.
halogens such as chlorine or bromine, nitro or sulphonic acid groups.
We have also found that the sulphur content of the starting material has a bearing on the viscosity of the product for a given T.B.N. For example, we prefer to use a 70% nonyl phenol sulphide 30% oil mixture containing from 5.5% to 7.5% by weight of sulphur to obtain a lubricant additive of T.B.N. in the range 230 to 260.
The sulphurised bridged phenol will generally be of the general formula:
~H OH
Rl ~ x ~ R
where R and Rl may be the same or different and may represent one or more alkyl groups. These sulphurised alkyl phenols may be obtained as mixtures of deriva-tives based on mono and di alkyl phenols or predominantly mono alkyl and the process of the present invention ls equally applicable to both types of sulphuris-ed alkyl phenol although we find the improved products are generally obtained when using the predominantly mono alkyl phenol. These sulphurised phenols are obtained by reacting the substituted phenol with a sulphur chloride e.g. SC12 such sulphurised phenols having one or more hydrocarbyl groups as substituents, each substituent having not more than 60 carbon atoms. The preferred sulphurised phenols are of the formula set out above and having one hydrocarbyl group containing for example 9 to 15 carbon atoms, per benzene ring, preferably the ' -- 5 _ ;

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,: . , hydrocarbyl group is in the para position with respect to the hydroxyl group.
There may be 1, 2, 3 or 4 sulphur atoms in the bridge linking the two phenyl groups, generally 1 or 2. Generally sulphurised bridged phenols are mixtures and we prefer to use material containlng an average from 1.5 to 1.7 sulphur atoms per pair of phenyl groups. We prefer that the sulphurised phenol con-tain from 7.5 to 11.0% by welght of sulphur.

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The non-volatile diluent oil can be any diluent oil, such as paraffinic or naphthenic hydrocarbon oil, e.g. of mineral origin obtained by conventional refinin Alternatively synthetic lubricating oils, vegetable oils, animal oils or mixtures of such oils may be used. We find that oils which have viscosities of 15 to 30cS
at 100 F are very suitable. As a furthur alternative one could use a lubricating oil of the klnd described later in the specification.

I The alkoxyalcohol in excess of that required to dissolve the magnesium alkoxyalkoxide will act as a general solvent for the process of the present invention.
We prefer to have from 25% to 50% by weight of excess alkoxylalcohol. I~hilst the process of the present invention does not generally require a second solvent of the type described in United States patents 3718858; 3746698 and 3775170 the use of such a second solvent is not excluded from the invention. In some instances, particularly in the preparation of materials from sulphurised phenols with a high sulphur content a second solvent may be required. When a solvent is used it should be volatile and we prefer to use hydrocarbons such as hexane although chlorinated solvents such as carbon tetrachloride or chlorobenzene may be used.

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In practice it is desirable to decide the relative amounts of metal alcoholate and surfactant according to the T.B.N. (total base number) desired for the overbased additive. The amount of ether alcohol in which the alcoholate is dissolved is determined to some extent by the nature of the alcohol, and the amount of'oil is governed by.the requirement for a workable reaction medium of suitable viscosity as well as its amount in the final product, the finished product typically being about 60 wt.~ active matter. .
In a typical reaction mixture for producing overbased phenates the amounts of reactants are as follows:
Molar Proportion Hydrocarbyl substituted sulphurised phenol magnesium alkoxyalkoxide 2-5 Oil - about 35-40 wt.% of total weight of finished product.
The water may then be added preferably mlxed with the ether alcohol from which the metal alkoxyalkoxite is prepared. If water is added alone there can be a delay in hydrolysis which can cause a gel to be formed and the presence of the ethoxy ethanol is thought to result in better dispersion of the water, we prefer to use a 50:50 mixture. We prefer to use at least 1.4 moles of water for each metal atom of magnesium present in excess of the number of magnesium atoms re-quired to react with the sulphurised phenol. Most preferably we use an amount of .. . . ... ..
water in the range 1.4 moles to 2 moles of water for each excess magnesium atom.

The reaction mixture ls preferably heated when the water is present to ensure hydrolysis of the magnesium alkoxyalkoxide preferably it is at a temperature in the range 50C to 70C. We prefer to use a temperature of about 60C since if the temp-erature durlng hydrolysis is below about 50C the reaction mixture tends to become too viscous and can separate into two layers. If however the temperature rises above 70C the final product tends to be of high vlscosity. Once hydrolysis is complete carbon dioxide is passed through the product durlng which the temperature of the reaction _ 7 _ '~.1.

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. , Finally, the volatiles consisting mainly of the ether alcohol and a solvent if one is used are removed from the reaction mixture. This can be done by distillation and if necessary blowing with carbon dioxide or an inert gas such as nitrogen. It is preferable to keep the distillation temperature below 50C to avoid decomposition of the product which can result in unpleasant odours and if a high boiling ether alcohol has been used in the reaction whose removal is difficult without exceeding the decomposition temperature of the desired product, low pressure distillation may be used.
The preferred product is found to be a colloidal suspension in oil of magnesium compounds, mainly carbonate but including basic carbonate, oxide or hydroxide together with magnesium surfactants acting as dispersant, the average diameter of the colloidal particles generally is less than 60 A.
Usually the finished product is 50-70~. e.g. 60~ active ingredients in oil. Its TBN can vary from 150 to 400, usually 200-300, e.g. 240-260. I~e find that the process of the present invention allows a higher TBN product (around 250) to be obtained consistently without viscosity problems and without the need for a second 60~vent although, the use of one is not excluded.
The ma~or constituents of the magnesium metal sulphurised phenates obtained by our process have the structure:
Mg ,,, ~ ' :~ O o x ~ R(n) where R is a hydrocarbyl group. The final product can be a mixture of such phenates where x and n vary for different molecules and minor .~ .
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amountS of compounds in which more than two aromatic rings are joined by sulphur links may be present however generally n is 1 and/or 2 and x is 1 or 2 and possibly 3 or 4 with an average value of from 1.5 to 2.
As mentioned the process of the present invention does not generally require a second solvent which is particularly advantageous since the absence of the solvent allows more active material to be obtained from a certain size vessel and obviates the need to remove and recover this solvent.
We find that the final colloidal suspension in the oil obtained by our process generally contains very little, often less than 0.05% by weight of sediment so that filtration may be not needed.
According to a further embodiment of our invention we add a minor amount of a 6ulphonate or a sulphonic scid to the reaction mixture. We find that in some instances the presence of the sulphonate gives the final product improved solubility in highly viscous oils and also reduces the tendency of the product to form a skin. We believe that the presence of the sulphonate or sulphonic acid helps to 8tabilisè the colloid and we find that best results are obtained if it is added to the initial reaction mixture prior to carbonation and that no more than about 6% by weight of sulphonate or sulphonic acid based on the weight of final product is sufficient to achieve the desired effect.
; The overbased detergent additives prepared by the process of this invention are very suitable for use in lubricating oils where their detergent properties inhibit formation of undesirable sediments whilst the high TBN of the product neutralises acids which may originate from fuel combustion thus reducing engine corrosion. The lubricating oils can be any animal, vegetable or any of the traditional mineral oils for example petroleum oil to SAE 30, 40 or 50 lubricating oil grades, castor oil, fish oils or oxidised mineral oil.
Alternatively the lubricating oil can be a synthetic ester lubricat-ing oil and these include diesters such as di-octyl adipate, di-octyl sebacate, didecyl azelate, tridecyl adipate, didecyl succinate, didecyl glutarate and mixtures _ g _ nl ~` 1085385 .

thereof. Alter~atively the synthetic ester can be a polyester such as that prepared by reacting polyhydric alcohols such as trimethylolpropane and pentaerythritol with monocarboxylic acids such as butyric acid to give the corresponding tri- and tetra- esters. Also complex esters may be used, such as those formed by esterification reactions between a carboxylic acid, a glycol andan alcohol or a monocarboxylic acid.
The overbased detergent is generally added to the lubricating oil as a concentrate and we find that between 0.01~ and 30~ by weight, preferably between 0.1% and 5% by weight of a concentrate consisting of 60 wt.% magnesium carb~nate plu8 metal sulphurised phenate and 40 wt.% oil is particularly useful.The final lubricating oil composition may if desired contain other additives e.g. a Viscosity Index improver such as an ethylene-propylene copolymer, an overbased calcium sulphonate or a dispersant such as polyiso-~i' butylene succinamide.
rJ The present invention ~s illustrated by reference to the following ~`i examples.
In Exsmples 1 to 5 Sulphurised Nonyl Phenol A was a product made from nonyl phenol containing 35 wt.% of dinonyl phenol diluted with a non-volatile oil to 70% by weight active ingredient. Sulphurised Nonyl Phenol A contained 7.4% by weight of sulphur and had a hydroxyl number of 131.
Sulphurised Nonyl Phenol B was prepared by adding 200 grams of sulphur ,~"
` dichloride to 660 grams of monononyl phenol dissolved in hexane followed by , vacuum stripping. The product contained 8.7% by weight of sulphur and had a molecular weight of 484.
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The magnesium alkoxylalkoxide was prepared by dissolving magnesium metal ~'J ' in about ten times its weight of ethoxyethanol to give a solution containing ,~ from 8.8 to 9.0% by weight of magnesium.
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: 10853~35 Example 1 The following mixture was made 374 grams magnesium alkoxy alkoxide (9.0% Mg) :250 grams sulphurised Nonyl Phenol A
250 grams of Naphthenic hydrocarbon ~diluent oil of viscosity 5cS at 210F
;~and stirred at 50C ove~ a period of 2 hours whilst a mixture containing 27 grams of water and 27 grams ethoxyethanol was run in. Carbon dioxide was then passed into the resulting product which was maintained at 50 C until 2g grams of carbon dioxide has been absorbed. The addition of carbon dioxide was then continued while the temp~rature was slowly raised to 150 C. The pressure in the reaction vessel was then slowly reduced to about 25 centimetres of mercury and the volatile materials stripped off. The resulting product was found to contain only 0.04~ by volume of sediment which was removed by filtration.
The final product had a TBN of 250 and a viscosity of 529 centistokes at 210F and performed well as an additive in lubricating oils.
ExamPle 2 The process of Example 1 was repeated with 220 grams of sulphurised nonyl phenol B and 280 grams of the diluent oil. The mixture was hydrolysed with a ,mixture of 36 grams of water and 36 grams of ethoxyethanol and 43 grams of carbon tioxide were absorbed before stripping. The final product weighed 609 grams before filtering, had a TBN of 254 and a viscosity of 427 centistokes at 210F .
ExamPle 3 Example 1 was repeated except that 300 grams of sulphurised nonyl phenol A
were used, the amount of diluent was reduced to 200 grams and the carbon dioxide charge increased to 44 grams. The total base number of the product was 249 and the viscosity at 210 F was 753 centistokes.

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': ' Example 4 The process of Example 3 was repeated using only 18 grams of water. The product obtained had a TBN of 248 but formed a skin on exposure to air and could not be poured.
Example 5 An overbased sulphurised magnesium phenate was prepared in a 40 gallon reactor by charging 60 kilogrammes of the magnesium alkoxyalkoxide, 32.3 kilogrammes of the naphthenic hydrocarbon oil and 48.4 kilogrammes of the sulphurised nonyl phenol A into the reactor. The mixture was stirred at 60 C
and hydrolysed by adding 8.6 kilogrammes of a 50% by weight mixture of water and ethoxyethanol evenly over a period of 2 hours. The mixture was then stirred for a further two houræ and the reactor heater then turned off. Carbon dioxide was passed inSo the bottom of the reactor at the rate of 30 litres per minute and the amount of unabosrbed carbon dioxide was measured by weighing a caustic soda trap attached to the exit from the reactor.
The reaction temperature and C02 absorbed by the reaction mixture was as follows:
Hours of C02Kilograms C02 Reaction Temperature Introduction absorbed C

~j 1.8 69 1 3.6 75 11 4.9 79 2 6.0 80

3 6.1 79

4 6.4 77 The rate of introduction of carbon dioxide was then reduced to 10 litres/
minute, the temperature raised to 150C and the pressure in the vessel reduced to 60 millimetres of mercury to remove volatile materials.

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iO85385 The product was found to contain 0.04% by volume of sediment which was completely removed by adding 250 grams of Dicalite Special Speed flow filter aid and then filtering through a plate and frame filter.
The yield or filtered material was 94.6 kilogrammes of colloidal dispersion in oil having a sediment less than 0.01% with a TBN of 236 and a viscosity of 321 centistokes at 210 F.
The products of all the above Examples were found to perform well as dispersants and neutralising agents in lubricating oils.
ExamPle 6 The following ingredients were charged to a 40 gallon reaction vessel:
(i) 65 kilogrammes of a solution of magnesium ethoxyethoxide in ethoxy-ethanol containing 8.75 wt.% magnesium (ii) 43.6 kilogrammes of sulphurised monononyl phenol having a hydroxyl number of 178 and containing 7.7 wt.% sulphur (iii) 3.3 kilogrammes of C24 alkyl benzene sulphonic acid (iv) 32.4 kilogrammes of a paraffinic diluent oil The mixture was heated to 60C and 11.4 kilogrammes of a 50 wt.% water and eth-oxyethanol methanol mixture were then run into the reactor over a period of 1 hour.

Carbon dioxide was next passed into the reactor for a period of 4 hours at ~` a rate of 20 litres per minute whilst the temperature was allowed to increase by 10 C per hour. ~bsorption of carbon dioxide was complete after 4 hours and the rate of introduction was then reduced to 10 litres per minute and the temperature -raised to 150C and the pressure reduced to 30 millimetres of mercury. 59.4 ~ kilogrammes of ethoxyethanol containing 1% by weight of water were distilled off.
i~ After centrifugation for 30 minutes in white spirit the product had a sediment of 0.08 wt.% and after addition of 250 grams of filter aid and then filtering and washing the reactor with 5.0 kilogrammes of diluent oil the combined weight of filtrate and washing was 99 kilogrammes. The product had zero sediment, a TBN of 252 and a viscosity at 210 F of 240 centistokes.
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The product contained 5.5 wt.~ magnesium 3.44 wt.% sulphur 0.26 wt.~ chlorine ExamPle 7 1500 grams of nonyl phenol (65 wt.% monononyl phenol and 35 wt.% dinonyl phenol) having a hydroxy number of 216 were mixed in a reaction vessel with 606 grams of a hydrofined paraffinic oil of viscosity 4cS at 210F at a temperature between ôO C and 90 C. 430 grams of a mixture containing 60% SC12 and 40% S2C12 were then added over a period of 4 hours after which the product was blown with nitrogen at 100C over a period of 8 hours to remove hydrochloric acid.
2300 grams of a product were obtained which had a hydroxyl number of 138 and contained 6.87 wt.% sulphur and 0.25 wt.% chlorine.
2100 grams of this product were mixed with 1260 grams of a paraffinic diluent oil having a viscosity of 4cS at 210 C, 140 grams of an 88% active in8redient oil~solution of a C24 alkylbenzene sulphonic acid and a magnesium .
alkoxy alkoxide prepared by dissolving 240 grams of magnesium in 2400 grams of ethoxyethanol. This mixture was stirred vigorously at 60 C whilst 380 grams of a 50 wt.% water ethoxyethanol mixture was run in over a period of 2 hours. The product was then saturated with carbon dioxide at a temperature between 60C
and 80 C, 258 grams of carbon dioxide being absorbed. After stripping 4350 grams ~f material of TBN 251 and having a viscosity at 210F of 502 centistokes was obtained. When the product was diluted with more diluent oil to have a TBN of 241 the viscosity at 210 F reduced to 333 centistokes.
ExamPle 8 52 kilogrammes of the sulphurised nonyl phenol A containing 35 wt.% dinonyl phenol and 65 wt.% monononyl phenol and 6.7 wt.% sulphur having a hydroxyI
number of 121 were charged to a reaction vessel together with 62 kilogrammes of ~1 , a solution of magnesium ethoxyethoxide containing 8.7 wt.% magnesium and 31.3 .
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kilogrammes of a diluent oil viscosity of 4cS at 210F. The mixture was stirred at 60C and 8.4 kilogrammes of a 50% by wt. mixture of water and ethoxyethanol added over a period of 2 hours.
Carbon dioxide was then passed into the reaction vessel at the rate of 20 litres per minute for a period of 4 hours during which the temperature was allowed to rise to oOC and 6.2 kilogrammes of carbon dioxide were absorbed. When there was no further absorption of carbon dioxide the rate at which it was introduced was reduced to 10 litres per minute and the temperature slowly raised to 150C;
when the temperature reached 120C the pressure was gradually reduced until ethoxyethanol started to distil and this was allowed to continue until there was no further distillation of ethoxy ethanol.
The product which contained 0.05~ sediment had a TBN of 242 and a viscosity of 372 centistokes at 210 F.

Example 9 1225 parts of 70~ active ingredient dodecyl phenol sulphide of hydroxyl number 133 containing 7.2 wt.~ sulphur, 728 parts of diluent oil and 65 parts of C24 alkyl benzene sulphonic acid were added to 144 parts of magnesium dissolved - 15 ~
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in 1444 parts of ethoxyethanol held at 60C. 144 parts of water mixed with 432 parts of ethoxyethanol were added slowly to the original mixture which was then at 65C.
After the addition of the water/ethoxyethanol mixture carbon dioxide was passed into the reaction vessel whose temperature was held at 65 C until 137 parts of carbon dioxide had been absorbed. The introduction of carbon dioxide was continued whilst the product was stripped to 150C and 50 millimetres mercury pressure.
Upon filtration a product was obtained that had a TBN of 242 and a viscosity of 391 centistokes at 210F.
Analysis of the product showed 5.3 % magnesium 3.8 % sulphur Example lO
The products of Examples 7, 8, 9 and lO were included in lubricating oils based on a MIL-C lubricating oil and containing, 3.7 wt.% of an ashless polyamine dispersant and 1.2% by weight of neutral calcium phenate, 1.2 wt.~ of a zinc dislkyldithiophosphate and 1.2 wt.% of magnesium sulphonate.
These oils were subjected to the following tests to determine thelr suitability as lubricating oils:
(i) The MS IIC anti-rust test (ASTM STP 315 F) (ii) The L38 bearing corrosion test (SAE publication 680538) (iii) The Modified Catalysed Oxidation test (Mod COT) in which an oil sample containing 0.1 wt.% iron naphthenate is stirred with a paddle !, *
.i made from a Petter W-l engine bearing with air blowing at 171 C and the % increase in the viscosity in the viscosity of the oil after 30 and 48 hours is measured.
(iv) Differential Scanning Calorimeter (DSC) in which an oil sample is heated in an aluminium pan in air at 210C and lOO psi pressure. After a certain length of time (the induction time) the oil oxidises and the heat of oxidation is measured. The induction time and the heat of oxidation are then combined according to the following formula:

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L = 1.5188 log10 G - 0.3167 log10 F
where G = induction period in minutes F - heat of oxidation in calories per gram.m to give the "b " value which gives an indication of the oxidation stability of the oil. The lower the ~ value the greater the oxidation stability.
The results of these tests are as follow: .
Mod COT
MSIIC BWL Visc. Increase~ DSC
Magnesium Phenate l~t.~Value Mg. 30H 48H Value Example 7 2.5 - 26.0 Example 8 1.5 - 65.5 llO 390 0.6 Fxample 8 2.5 8.1 59.5 120 550 1.0 Example 9 1.5 - 28.0 140 - 1.0 Example 9 2.5 7.6 25.0 230 - 1.0 ; Example 10 1.5 - 44.3 170 780 0.8 Example 10 2.5 8.5 4.55 170 670 0.6 L ~ ~

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process comprising the following steps:
(i) forming a reaction mixture comprising:
(a) a magnesium alkoxyalkoxide together with the alkoxyalcohol (b) a surfactant being a sulphonic acid or metal sulphonate or one or more hydrocarbyl substituted phenols or metal phenates wherein the or each hydrocarbyl group contains up to 60 carbon atoms or one or more sulphurised phenols having one or more hydrocarbyl group substituents each substituent containing up to 60 carbon atoms or mixtures of said surfactants.
(c) a non-volatile diluent oil (d) at least one mole of water for every gram atom of the alkaline earth metal present in excess of the amount of the metal required to neutralise the surfactant (ii) hydrolysing the magnesium alkoxyalkoxide (iii) introducing carbon dioxide into the reaction mixture (iv) removing volatiles from the reaction mixture

2. A process according to claim 1 in which the magnesium alkoxide is prepared in situ.

3. A process according to claim 1 in which the magnesium alkoxide is prepared in situ by reacting magnesium metal with an alkoxy alcohol.

4. A process according to claim 1 in which the alkoxyalcohol is ethoxyethanol.

5. A process according to claim 1 in which the surfactant is phenolic and the or each hydrocarbyl substituent in the hydrocarbyl substituted phenol has at least nine carbon atoms.

6. A process according to claim 5 in which the or each hydrocarbyl substituent has from 9 to 15 carbon atoms.

7. A process according to claim 5 in which the phenol is a sulphurised phenol of the general formula:

where R1 and R are the same or different and represent one or more alkyl groups and x has an average value from 1 to 2.

8. A process according to claim 7 in which the sulphurised phenol contains at least 90% by weight of material in which R1 and R represent one alkyl group.

9. A process according to claim 7 in which the sulphurised phenol contains from 7.5% to 11.0% by weight of sulphur.

10. A process according to claim 5 in which up to 6% by weight of a sulphonate or sulphonic acid is added to the reaction mixture.

11. A process according to claim 1 in which the surfactant is a C18 to C30 alkyl benzene sulphonic acid or sulphonate.

12. A process according to claim 1 in which there is from 25% to 50% by weight excess alkoxyalcohol present above that required to dissolve the magnesium metal alkoxyalkoxide.

13. A process according to claim 1 in which the water is added to the mixture of the solution of the magnesium alkoxyalkoxide and the surfactant.

14. A process according to claim 13 in which the water is added in admixture with the alkoxy alcohol.

15. A process according to claim 1 in which at least 1.4 moles of water are used for each metal atom present in excess of the number of metal atoms required to react with the phenol.

16. A process according to claim 1 in which the reaction mixture is at a temperature in the range 50°C to 70°C during the hydrolysis.

17. A process according to claim 1 in which the temperature is maintained below 100°C until the reaction mixture is saturated with carbon dioxide.