US3928216A

US3928216A - Preparation of overbased magnesium lubricant additives

Info

Publication number: US3928216A
Application number: US510038A
Authority: US
Inventors: Peter Anthony Saunders; Michael Frank Fox; Anthony Francis Fagan; Philip Edward Derbyshire
Original assignee: Edwin Cooper and Co Ltd
Current assignee: Edwin Cooper & Co; Edwin Cooper and Co Ltd
Priority date: 1971-05-27
Filing date: 1974-09-27
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: AU468371B2; CA985668A; AU4282072A; DE2225714A1; DE2225714B2; DE2225714C3; FR2139120A1; NL7207250A; AT326252B; US3857790A; GB1399092A; ATA460872A; FR2139120B1

Abstract

A process for preparing overbased lubricant additives comprises: A. FORMING IN AN INERT SOLVENT A REACTION MIXTURE OF, I. AN OIL-SOLUBLE DETERGENT OR DISPERSANT, II. A BASIC ALKALINE EARTH COMPOUND, III. A HYDROXY CONTAINING ORGANIC COMPOUND, AND IV. AS PROMOTER, AN AMINE SALT OF AN ACID; B. TREATING THE REACTION MIXTURE WITH AN ACIDIC GAS; AND C. HEATING THE RESULTANT PRODUCT TO REMOVE VOLATILE COMPONENTS. Also described are lubricants containing the overbased additives as detergents and dispersants.

Description

United States Patent 1191 Saunders et a1.

[ Dec. 23, 1975 PREPARATION OF OVERBASED MAGNESIUM LUBRICANT ADDITIVES Inventors: Peter Anthony Saunders; Michael Frank Fox; Anthony Francis Fagan; Philip Edward Derbyshire, all of London, England Edwin Cooper & Company, London, England Filed: Sept. 27, 1974 Appl. No.: 510,038

Related US. Application Data Division of Ser. No. 257,424, May 26, 1972, Pat. No. 3,857,790.

Assignee:

Foreign Application Priority Data May 27, 1971 United Kingdom 17604/71 References Cited UNITED STATES PATENTS 4/1963 Sabol et a1. 252/46.7 X

5/1966 Vogel 252/32.7 HC 4/1967 LeSuer et a]. 252/33 3,429,811 2/1969 Robbins et a1 252/18 X 3,480,548 11/1969 Hellmuth et a1. 252/33.4

3,595,790 7/1971 Norman et a1 252/33 X 3,609,076 9/1971 Sabol et a1. 252/18 X 3,629,109 12/1971 Gergel et al 252/32.7 l-lC X 3,691,075 9/1972 S ias 252/39 X 3,829,381 8/1974 LeSuer 252/33 X R27,582 2/1973 Kahn et a1. 252/18 X FOREIGN PATENTS OR APPLICATIONS 1,225,039 3/1971 United Kingdom 44/51 Primary ExaminerDelbert E. Gantz Assistant ExaminerAndrew H. Metz Attorney, Agent, or FirmBacon & Thomas [57] ABSTRACT A process for preparing overbased lubricant additives comprises:-

a. forming in an inert solvent a reaction mixture of,

i. an oil-soluble detergent or dispersant, ii. a basic alkaline earth compound, iii. a hydroxy-comtaining organic compound, and iv. as promoter, an amine salt of an acid; b. treating the reaction mixture with an acidic gas;

and c. heating the resultant product to remove volatile components. Also described are lubricants containing the overbased additives as detergents and dispersants.

22 Claims, No Drawings PREPARATION OF OVERBASED MAGNESIUM LUBRICANT ADDITIVES This is a division, of application Ser. No. 257,424, filed May 26, 1972 and now US. Pat. No. 3,857,790.

This invention relates to lubricant additives, and in particular to the preparation of overbased lubricant additives, which are detergents and dispersants, and to compositions containing the additives so prepared.

In the lubrication of modern internal combustion engines deposits, such as soot, lacquers and sludge, may be formed and detergent and/or dispersant additives are commonly incorporated in lubricants to counteract such deposits. It has been found that basic detergents and dispersants, i.e. detergents and dispersants having a high content of an alkali or alkaline earth metal salt of a weak acid such as carbonate, are particularly useful. The basicity of such additives counteracts corrosive acidic compounds, e.g. combustion products, which are formed during the operation of engines.

The basic additives are commonly prepared by'a process consisting essentially of suspending a basic metal compound, e.g. calcium hydroxide or oxide, in an inert solvent (usually lubricating oil) containing a detergent or dispersant, such as a carboxylic or sulphonic acid or metal salt thereof, and passing an acidic gas, usually carbon dioxide, through the suspension. This process, which is often referred to as overbasing, produces a product in which the metal compound is complexed or dispersed in the lubricating oil. Ideally, the product should be a clear liquid which is stable, i.e. the basic metal compound which should not separate from the liquid phase, and in which the metal of the r'netalcompound is present in an excess of the stoichiometric amount required to react with the acid groups of the detergent or dispersant. For many purposes it is desirable for a very large excess of metal to be present. Moreover, the overbasing process should have good repeatability. That is to say there should be a high degree of consistency in the quality of products obtained when the process is carried out repeatedly under identical conditions, as happens when commercial production is undertaken.

Although calcium and barium compounds were initially the most commonly used metal compounds, more recently magnesium compounds have become of greater interest because of the lower ash content of lubricants containing magnesium. However, it has been found that the overbasing process usually applied to calcium and barium compounds cannot be modified in a simple manner to produce basic detergents and dispersants containing magnesium. Attempts to produce magnesium-containing basic detergents and dispersants have commonly been uneconomic or have yielded products having inferior properties.

Among the variations in technique which have been proposed for the overbasing process is the incorporation of a promoter in the reaction mixture to improve the process and the properties of the product. This is illustrated by US. Pat. No. 3492230 of Jan. 27, 1970, to R. W. Watson. E. E. Richardson and A. R. Sabol, which discloses the use of ethylene diamine as promoter, and by US. Pat. No. 3629109 of Dec. 21, 1970, to W. C. Gergel, J. L. Karn and L. E. King. However, as far as the preparation of overbased magnesium-containing detergents and dispersants are concerned, there remains a need for an economical process for preparing a technically suitable product. Thus, techniques hitherto proposed for using magnesium oxide or hydroxide as a source of magnesium have been uneconomic, e.g. by virtue of being multi-stage processes, and/or have produced additives lacking, to an unacceptable degree, one or more of the properties of clarity, basicity, consistency of quality and performance in engine tests. The products have been unsuitable therefore for economic or technical reasons. To the best of our knowledge and belief overbased magnesium-containing detergents have not been produced on a commercial scale from magnesium oxide or hydroxide and the only commercially used method employs magnesium metal, despite the unfavourable economics of using such expensive starting materials.

We have now found that certain compounds are effective promoters, such that by using these compounds, it is possible to obtain an improvement in one or more of the properties of clarity, basicity, repeatability and performance in engine tests even when the alkaline earth metal present is magnesium.

Accordingly, the present invention provides a process for preparing an overbased lubricant additive, which process comprises:

a. forming in an inert solvent a reaction mixture of,

i. an oil-soluble detergent or dispersant,

ii. a basic alkaline earth compound,

iii. a hydroxy containing organic compound, and iv. as promoter, an amine salt of an acid;

b. treating the reaction mixture with an acidic gas;

and

c. heating the resultant product to remove volatile components.

The inert solvent employed in the process of the present invention may be a lubricating oil of the synthetic ester type well known in the art. An example of such esters is dioctyl sebacate. Further examples of these esters are described in UK. Pat. No. 1,205,177 the relevant portions of which are incorporated herein by reference. Such esters are also available commercially, for example, the range of pentaerythritol esters marketed under the trade name Hercolube." However, it is preferred to use a hydrocarbon solvent such as petroleum oil of the type used in lubricating compositions. Alternatively, the hydrocarbon oil vehicle may consist of a synthetic hydrocarbon oil, for example, an alkylated benzene fraction, or a mixture of such an oil with petroleum oil.

In yet another alternative the inert solvent may be a non-polar diluent, particularly a hydrocarbon diluent, as referred to hereinafter. Such diluents of comparatively low viscosity, may be useful when the detergent or dispersant is a pure sulphonic acid or salt thereof which is solid or a highly viscous liquid.

The proportions of the inert solvent which is employed can vary widely depending on the proportions of the other components of the reaction mixture. Indeed the proportion of each component can vary according to the varying proportions of each of the other components. In view of this interdependency of the proportions it is convenient to take the amount of the inert solvent as a reference point and relate the proportions of other components thereto.

Oil-soluble detergents or dispersants which are susceptible to overbasing are well known in the art and the material used in the present process may be selected from those conventionally used in overbasing processes, such as phosphosulphurised hydrocarbons, e.g. polyisobutylene treated with phosphorus pentasulphide, or metal salts of carboxylic acids, particularly alkanoic acids, e.g. acetic or fatty acids, or naphthenic acids. Suitable oil-soluble detergents or dispersants include those disclosed in the aforementioned US. Pat. Nos. 3492230 and 3629109. It is particularly preferred to use a sulphonic acid or metal salt thereof, especially a metal salt wherein the metal is an alkaline earth metal. In a preferred embodiment the metal is the same as the metal present in the basic alkaline earth compound.

The sulphonic acid may be a petroleum sulphonic acid (also termed mahogany sulphonic acids) prepared by sulphonating petroleum feedstocks or it may be an alkyl, aryl or alkaryl sulphonic acid. Examples of such sulphonic acids include petroleum sulphonic acids of molecular weight 350 to 750, dilauryl aryl sulphonic acid, lauryl-cetyl aryl sulphonic acid, paraffin wax-substituted benzene sulphonic acid, didodecyl benzene sulphonic acid, polyolefm alkylated benzene sulphonic acids, such as polyisobutylene alkylated benzene sulphonic acids in which the polyisobutylene substituents have molecular weights of at least 200, preferably from 300 to 2, 500, polypropylene alkylated benzene sulphonic acids in which the polypropylene substituents have molecular weights of at least 200, preferably from 290 to 1,500, naphthalene sulphonic acids and alkylsubstituted naphthalene sulphonic acids. Particularly preferred sulphonic acids are mono-alkyl substituted benzene sulphonic acids having molecular weights of from 450 to 550, for example, the commercially available product Monsanto M 5336 (straight chain monoalkyl substituted benzene sulphonic acid of molecular weight 470 to 480).

The amount of detergent or dispersant employed may be varied over a wide range. We prefer to use from more preferably at least up to 120 or even 150% by weight based on the weight of the inert solvent. A particularly preferred proportion is from 60 to 120% by weight.

The basic alkaline earth compounds useful in overbasing processes are also well known, examples being oxides and hydroxides such as magnesium, barium and calcium oxides and hydroxides, the magnesium compounds, especially magnesium oxide, being preferred.

Thus, although particularly suitable for preparing overbased magnesium-containing additives the process of the present invention can also be used for preparing overbased additives containing other metals. The amount of the basic alkaline earth compound to be employed may be readily calculated from the intended basicity of the additive product. The maximum basicity which can be achieved will depend, inter alia, on the degree of susceptibility of the detergent or dispersant. In overbasing magnesium salts of sulphonic acids it may be possible to achieve a total base number (T.B.N) as high as 600mg KOH/g. However, it is preferred to use sufficient base to produce a T.B.N. of 250 to 500, more preferably 300 to 400, mg.KOH/g. Additives having this level of basicity are regarded as highly basic and the process of the present invention is particularly suitable for preparing such highly basic additives. However, additives of lower basicity are also useful commercial products and may also be prepared by the process of the present invention.

To allow for incomplete utilisation of the base it may be desirable to use a small amount in excess of that theoretically required to produce the desired basicity.

As hereinbefore indicated magnesium oxide is the most preferred basic alkaline earth compound for use in the present invention. Magnesium oxide is commercially available in two forms, sometimes referred to as light and heavy magnesium oxide. The former is a relatively active form, usually derived from extraction from sea water. Heavy magnesium oxide, sometimes called dead burned," is produced by mining and roasting of the mineral material and is commonly considered a less active form of magnesium oxide. In the present invention either form of magnesium oxide may be used. Light magnesium oxide, such as the commercially available material Merck Maglite Y3234 supplied by Merck Chemical Division, N.J., is preferable from the viewpoint of providing a somewhat more easily controlled process and somewhat better product; whereas heavy magnesium oxide, which is less expensive, may be used without introducing undue difficulty into the operability of the process and without too serious a reduction in the quality of the product.

The hydroxy compound employed in the reaction mixture is believed to act as a co-promoter with the amine salt of an acid. Examples of suitable hydroxy compounds include alcohols, glycols and glycol monoethers. The choice of hydroxy compound is not critical. However, for ease of removal of the hydroxy compound from the product of the process it is preferred that the hydroxy compound has as low a boiling point as possible. For this reason the hydroxy compound preferably contains from 1 to 4 carbon atoms and the preferred hydroxy compounds are therefore lower alcohols, particularly alkanols, glycols containing from 1 to 4 carbon atoms, e.g. ethylene glycol, propylene glycol, butylene glycol or diethylene glycol, and monoethers of glycols containing from 1 to 4 carbon atoms, e.g. ethylene monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monisopropyl ether, ethylene glycol mono-n-propyl ether, propylene glycol mono-ethyl ether, propylene glycol mono-methyl ether, diethylene glycol mono-methyl ether or butylene glycol mono-methyl ether. The lower alkanols, particularly methanol, are especially preferred. The amount of hydroxy compound used is preferably at least 5%, more preferably 25 to 50% by weight based on the weight of the inert solvent.

In a highly preferred embodiment of the invention water is also present in the reaction mixture, for example in an amount of from 5 to 50%, more preferably 15 to 30% by weight based on the weight of the inert solvent. In the preparation of highly basic additives it may be desirable to subsequently add a further quantity of water, for example from 10 to 25% by weight based on the weight of the inert solvent, during the treatment of the reaction mixture with acidic gas.

The amine salt of an acid which is used as a promoter in the process of the present invention may be a salt of a mono-, dior poly-amine with an inorganic acid or an organic acid, e.g. a mono-, dior poly-carboxylic acid and the amine and/or the acid may be aliphatic or aromatic. Alternatively, a heterocyclic amine may be used. Thus, the promoter may be selected from salts of a large number of amines, although among these certain salts are preferred. Thus, salts of aliphatic amines with aliphatic carboxylic acids, particularly monocarboxylic acids, are especially useful. The salts are preferably neutral salts.

In a preferred embodiment of the invention the promoter is a salt of a carboxylic acid. If an aromatic carboxylic acid'is u'sed, thispreferably consists only of carbon and hydrogen atoms other than the two oxygen atoms in the, or each, carboxyl group. However salts of aliphatic carboxylic acids are preferred. Diand polycarboxylic aliphatic acids which may be used include those containing 2 to carbon atoms, examples being adipic, maleic, glutaric, succinic, and azelaic acids. Monocarboxylic acids, such as alkanoic acids, may also be used. Examples of particularly suitable acidsfrom which the promoters may be formed are alkanoic acids containing from 1 to 20 carbonatoms (including the carbon atom present in the carboxylic group). The most preferred acids are formic acid and alkanoic acids containing from 7 to 12 carbon atoms, e.g. decanoic.

The amines from 'which the salts are formed include monoamines, such as oleylamine and laurylamine, diamines, such as ethylene diamine of propylene diamine, and polyamines, such as diethylene triamine. Suitable amines also include those disclosed in the aforementioned U.S. Pat. No. 3492230. Preferred amines contain not more than 10 carbon atoms. Diamines and polyamines are the most preferred amine moiety, particularly those containing from 2 to 8 carbon atoms. Ethylene diamine is the most preferred amine and it is especially preferred-to use as the promoter the diformate salt of ethylene diamine.

The amount of the promoter used may be, for example, from-0.1% to 30 or 40% by weight, based on the weight of the inert solvent, within which range optimum proportions r'nay be-selected according to the amine saltused and the intended basicity. In the case of ethylene diamine diformate the preferred proportions of promoter are from 0.1 to more preferably 1.0 to 10% by weight based on the weight of the inert solvent. This may be varied according to the intended basicity of the product. For example, from 5 to 7% by weight of promoter may be used in the preparation of an additive having a T.B.N. of 300 and from 7 to 10% by weight in the preparation of an additive having a T.B.N. of 400.

In the case of other amine salts the preferred proportions are such as to give the same molar ratio of promoter to other components of the reaction mixture as in the case of the preferred proportions of ethylene diamine diformate.

There may also be included in the reaction mixture a non-polar diluent other than any used as, or as part of, the inert solvent, particularly a hydrocarbon diluent such as xylene, benzene, toluene or petroleum ether. This diluent assists in maintaining the reaction mixture at a low viscosity during the overbasing process and is preferably a volatile diluent which can be varied over a very wide range depending on the choice of other components in the reaction mixture and their effect on viscosity. ln a preferred embodiment of the invention from 80 to 150%, more preferably 100 to 130% by weight, based on the weight of the inert solvent, of toluene is used as diluent.

The components of the reaction mixture may be merely mixed in a reaction vessel and the order in which the components are added is not critical. However, a convenient technique is to prepare an aqueous solution of the promoter and add it to the remaining components previously mixed in the reaction vessel.

After formation of the reaction mixture an acidic gas is passed therethrough. The acidic gases which may be used in overbasing processes are a'lso'well-kn'own i'n'the art, examples being sulphur dioxide 'and hydrogen sulphide. However, a particularly preferred acidic gasis carbon dioxide. The pressure at which the reaction mixture is treated with the acidic gas is also not critical. A pressure above, below or at atmospheric may be used. Treatment-at atmospheric pressure is convenient as not requiring equipment to establish and maintain the pressure at which the reaction is carried out.

Alternately, an increase in pressure over atmospheric may assist utilization of the acid gas. For this purpose a small increase over atmospheric, e.g. up to 4 or 5 p.s.i.g., will suffice and normally only 1 or 2 p.s.i.g. is sufficient.

The temperature at which the process-is carried out is likewise not critical'and treatment with the acidic gas may take place at any temperature from ambient (about 20C) up to the decomposition temperature of the reaction mixture. The reaction is exothermic and the temperature of the reaction mixture will tend to increase as the reaction proceeds. If desired, this can be counterbalanced, e.g. by cooling, to maintain a low reaction temperature. At the upper end of the tempe rature range, the important factor in the decomposition temperature of the reaction mixture is the temperature at which significant deterioration of the product formed in the reaction mixture occurs. We prefer therefore to keep the reaction temperature below 180C., more preferably below 150C. However, the reaction temperature will also be affected by water, and non-polar diluent, if used, and the choice of hydroxy compound. Volatile components will be distilled off if the reaction temperature is too high. The reaction temperature therefore desirably does not exceed the boiling point of the most volatile component of the reaction mixture (normally methanol) or any azeotrope formed by components of the reaction mixture (e.g. a methanol/water/toluene azeotrope). It is normally advantageous therefore to carry out the reaction at or below the reflux temperature of the reaction mixture. In the case of reaction mixtures containing the more volatile hydroxy compounds, such as methanol, treatment at the reflux temperature has the advantage that a constant temperature is easily maintained. During treatment with the acidic gas the reaction mixture may be agitated to improve contact between gas and reaction mixture.

The acidic gas is passed through the reaction mixture until the basic alkaline earth compound is substantially converted to alkaline earth salt, whereafter the reaction mixture is heated to remove volatile components; e.g. water, methanol and any non-polar diluent. Preferably the volatile components are removed under reduced pressure, e.g. by vacuum stripping. Basic alkaline earth compound not consumed'during the overbasing process may be removed by filtration of the product. A filter aid, such as diatomaceous earth, may be used in the filtration, which may be carried out after stripping, although we prefer to filter before stripping off volatile components. Alternatively, in a very useful technique, water and volatile hydroxy compound, particularly 'in' the case of methanol, are substantially removed before filtration, and any non-polar diluent and remaining water and volatile .hydroxy compound are stripped off after filtration.

In a particularly preferred embodiment of the present invention there is provided a process for preparing an overbased lubricant additive, which process comprises:

a. forming in an inert solvent a reaction mixture of i. about 20 to by weight, based on the weight of the inert solvent, of an oil-soluble sulphonic acid or alkaline earth metal salt thereof,

ii. magnesium oxide or hydroxide,

iii. about 5 to 50% by weight, based on the weight of the inert solvent, of a lower alcohol, preferably methanol,

iv. about 5 to 50% by weight, based on the weight of the inert solvent, of water,

v. about 0.1 to 40% by weight, based on the weight of the inert solvent, of a salt of an aliphatic amine and an alkanoic acid, preferably the diformate salt of ethylene diamine, and, optionally,

vi. about 80 to 150% by weight, based on the weight of the inert solvent, of a non-polar diluent, preferably toluene or xylene;

b. passing carbon dioxide through the reaction mixture at a temperature of from about 20C up to the reflux temperature of the reaction mixture until the magnesium oxide or hydroxide is substantially converted to magnesium carbonate; and

c. heating the resultant product to remove volatile components, i.e. water, alcohol and any diluent present.

In the preceding paragraph, and also in the appended claims, by converting the magnesium oxide or hydroxide to magnesium carbonate is meant complexing or dispersing the magnesium in the inert solvent to form a stable, liquid product, by means of the treatment with carbon dioxide. As with other overbased additives, the exact chemical structure of the additives of the present invention is not completely understood.

The present invention further includes an overbased lubricant additive whenever prepared by the process of the present invention and a composition comprising a lubricating oil and an overbased lubricant additive prepared by the process of the present invention. Such compositions may be lubricant compositions containing a major amount of lubricating oil and a minor amount, for example 0.1 to preferably 0.5 to 5% by weight based on the total weight of the compositions of one or more overbased additives prepared by the process of the present invention. These lubricant compositions may also contain conventional additives such as antioxidants, corrosion inhibitors, anti-wear additives, detergents, dispersants, extreme pressure additives, viscosity index improvers, pour point depressants and/or load carrying additives.

Alternatively, the compositions may be concentrates containing a minor amount of lubricating oil and a major amount of one or more overbased additives prepared by the process of the present invention or additive packages containing a minor amount of lubricating oil and a major amount of an additive consisting of one or more additives prepared in accordance with the present invention in combination with one or more conventional additives.

The present invention will now be illustrated by way of example with reference to the following nonlimitative examples, in which weight percentages given for soap and Mg in the final product are based on the total weight of the product:

EXAMPLE 1 The following reactants were stirred together in a 2-litre flask:

208g. Esso HT 233 sulphonic acid (branched chain mono-substituted alkyl benzene sulphonic acid of molecular weight about 500; 70% active) 190g. Mineral Oil A.

g. Magnesium oxide (commercially available reagent grade of heavy oxide) 312g. Toluene 86g. Methanol A promoter was prepared by reacting 8g. formic acid with 5g. ethylene diamine in 25ml. water and the promoter was transferred to the 2-litre flask with the aid of a further 15ml. water. The mixture in the flask was then heated to its reflux temperature (about 67) and CO introduced, via a dip tube, into the mixture at a flow rate of 1.92 litres/min. Carbonation was continued for 2 hours.

The product of the carbonation was filtered with the aid of a filter aid. Toluene, water and methanol were removed from the product by vacuum stripping to C. The final product contained 6.7% by weight Mg., 30% by weight soap (magnesium sulphonate) and had a T.B.N. of 300 mg, KOH/g.

EXAMPLE 2 The following reactants were stirred together in a 2-litre flask:

208g. Esso HT 233 sulphonic acid 310g. Mineral Oil A.

g. Magnesium oxide (as in Example 1) 312g. Toluene 84g. Methanol A promoter was prepared by reacting 16g. formic acid with 10g. ethylene diamine in 501111. water and the promoter was transferred to the flask with the aid of a further 25ml. water. The mixture was then carbonated under reflux in the same manner as in Example 1., whereafter a further 50ml. water was added and carbonation continued for a further 2 hours.

The product was filtered and vacuum stripped as in Example 1, to yield a final product containing 8.7% by weight Mg., 20% by weight soap and having a T.B.N. of

EXAMPLE 3 Constituent quantities:

208g. Esso sulphonic acid HT 233 207g. Mineral Oil B 312g. Toluene 70g. Methanol 90g. Magnesium oxide (Merck Maglite Y3234) 10g. Ethylene diamine 16g. formic acid 90g. water The sulphonic acid, base oil, toluene, methanol and magnesium oxide were weighed into a 2-litre reaction flask fitted with a stirrer, reflux condenser, thermometer and a sub-surface injection tube for carbon dioxide.

These reactants were allowed to stir together for approximately 10 mins. in order to form the neutral magnesium sulphonate. The temperature rose from approx 20C to approx. 33C.

The ethylene diamine and formic acid were dissolved separately in 25g. and 50g. water, respectively. The two resulting solutions werecarefully mixed together with a further g. of water and the ethylene diamine difor-' Carbon dioxide gas was injected into the stirred reaction mixture via the injection tubea t a rate of 1.22 litres per minute. The passage of gas was continued for 1 hour, during which period the reaction temperature rose from 43C to 68C maximum.

The passage of gas was stopped and the product mixture was filtered through a bed of a filter aid.The filtration was rapid and the resulting filtrate was vacuum stripped to a maximum temperature of 180C and 50 mm. Hg'vacuum.

The product was clear, bright and mobile. The total base number (TBN) was 396mg. KOH/g., with a total magnesium content of 9.3%. The soap content was 25%.

Mineral Oil B used in this example had viscosities of about 22 and 4 cSt. at 100F and 210F respectively and a Viscosity Index of 95.

EXAMPLE 4 An additive having a TBN of 338mg. KOH/g.and containing 26.6% by weight soap and 7.86% by weight Mg was prepared by a procedure identical to and using the same quantities of the same materials as in Example 3, except in that 207g. dioctyl sebacate was used in place of Mineral Oil B. The product was a clear, bright liquid.

EXAMPLE 5 An additive having a TBN of 183mg. KOH/g. and containing 30.7% by weight soap and 4.64% by weight Mg was prepared by the same procedure as, and using the same quantities of the same materials as, Example 3 except for the following:-

a. Magnesium hydroxide (146g.) was used in place of the magnesium oxide.

b. The initial starting temperature was 19C.

c. The exotherm due to neutralisation of sulphonic acid increased the temperature from 19C to 28C.

d. Addition of the promoter solution increased reaction mixture temperature to 38C.

e. The exotherm during carbonation increased the temperature to 39C.

EXAMPLE 6 An additive having a TBN of 377mg. KOl-l/g. and containing 25.5% by weight soap and 8.66% by weight Mg was prepared using the same quantities of the same material as, and following the procedure of, Example 3 except in that carbonation was continued for 75 minutes and the temperature of the reaction mixture was maintained at 40C i 1C. throughout the carbonation. The product'was a clear, bright liquid.

EXAMPLE 7 An additive having a TBN of 298mg. KOl-l/g. and containing 27.6% by weight soap and 7.02% by weight Mg was prepared by the procedure of Example 3 except as follows:-

a. The methanol was replaced by g. methyl dioxitol (di-ethylene glycol monomethyl ether).

b. The starting temperature was 21C.

' cf'The exotherm due to neutralisation of sulphonic acid increased the reaction mixture temperature to 33C.

d. Addition of the promoter solution increased reaction mixture temperature .to 42.5C.

e. The exotherm during carbonation increased the temperature to 73C after 35 minutes and thereafter external heating was used to raise the reaction mixture to its reflux temperature (895C) during the remaining 25 minutes carbonation.

The product was a clear, bright, mobile liquid having excellent filterability.

EXAMPLE 8 A very highly basic additive (TBN 543mg.KOH/g.') containing 21.8% by weight soap and 1 1.35% by weight Mg. was prepared from the following materials:

208g. Esso sulphonic acid HT 233 207g. Mineral Oil B 312g. Toluene 140g. Magnesium oxide (Maglite Y3234) 70g. Methanol 7g. Ethylene diamine 11.2g. Formic Acid g. Water.

The procedure was the same as that of Example 3 except that during carbonation the temperature rose, due to the exotherm, to a maximum of 61C after 20 minutes and carbonation was continued for a total of 1% hours. Further preparations were carried out to demonstrate variations in the choice of the components of the reaction mixture. These preparations, and the results obtained, are summarized in the following Tables 1 to 6.

Table 1 shows the results obtained using various detergents and dispersants in the process of Example 3. Except in respect of the detergent or dispersant the materials used, and the quantities thereof, were the same as in Example 3.

Table 2 summarizes the preparation of additives of varying soap content by the process of Example 3. The quantities of the sulphonic acid and Mineral Oil B were varied to adjust the final soap content. All other components, and the quantities thereof, were the same as in Example 3.

Table 3 shows preparations wherein the same procedure as in Example 3 was used and the materials and quantities were the same as in Example 3, except in that the 70g. methanol was replaced by 70g. of various other hydroxy compounds.

Tables 4 and 5 show the use of differing amines and acids in the promoter. Table 4 summarizes preparations using the neutral formate salts of various amines, and Table 5 summarizes preparations usingethylene diamine salts of various'acids. Except for the indicated variations all the preparations were carried out using the same procedure, materials and quantities thereof as in Example 3.

Table 6 shows preparations using ethylene diamine salts of various acids, but the preparations were carried out using the same procedure, materials and quantities thereof as in Example 1, except for the indicated variations.

- 1n the preparations shown in Tables 1 to 6, for the purpose of illustration only, one component of the 1 1 reaction mixture has been varied and a standard preparative procedure has been used. To optimise reaction conditions and procedure for any particular variation simple adjustments can be made, the adjustments to be made being readily determinable. Moreover, it will be understood that various adjustments may be made to the process to suit the particular requirements and preferences of the operator. For example, viscosity control may be of less importance when the operator intends to immediately blend the product with a large quantity of lubricating oil, and other additives, toprepare a fully formulated lubricant. Alternatively, the process operator may, depending on the circumstances, wish to use various means to control viscosity such as using larger quantities of the less viscous components of the reaction mixture, filtering before removing volatile components to improve filterability (the volatile components are in general also the less viscous components) and/or selection of reaction mixture components (for example, in the case of the inert solvent synthetic ester lubricating oils normally have lower viscosities than mineral oils). Similarly, the rate at which and/or the period for which the reaction mixture is treated with the acidic gas may be varied according to such. factors as thedesign of the manufacturing plant and the level of basicity required by the process operator. Such variations in technique of a routine nature will be apparent to the process operator.

In the following Table 7 preparations using ethylene diamine diformate as promoter are compared with the use of ethylene diamine, under the conditions and procedure of Example 3 herein and also in accordance TABLE I EXAMPLE QUAN- T.B.N. of

TTTY DETERGENT/DISPERSANT PRODUCT NO. (gm.) (mg.KOl-l/g.)

9 Polyisobutylene substituted succinic acid prepared by l 160 reaction of maleic anhydride with l-lyvis (commercially available polyisobutylene of average molecular weight about 2000) l0 Succinimide prepared by formation of 1:1 molar reaction 1160 38 product of dicyandiamide and tetraethylene pentamine and reaction of this product with a polyisobutylene substituted succinic acid as in Example 9. l l Naphthenic Acid. 97 181 12 Magnesium sulphonate prepared by double decomposition 187 267 of a 50% solution in mineral oil (S.G. 0.9) of a sodium petroleum sulphonate with magnesium chloride. The sodium petroleum sulphonate had an average molecular weight of 460 to 465 and the mineral oil solution of the sulphonate consisted of 75 parts of a mineral oil solution (50%) of a medium molecular weight sulphonate and 25 parts of a mineral oil solution (50%) of a high molecular weight sulphonate. l3 Petroleum sulphonic acid (being the acid from which 156 333 the sodium petroleum sulphonate of Example l2 was derived).

TABLE 2 VARIATION OF SOAP CONTENT EXAMPLE REACTANTS T.B.N. SOAP CONTENT NO. HT 233 SULPHONlC AClD (gm.) MlNERAL OlL B (gm.) (mg.KOl-l/g.)' by weight) None inert solvent 14 416 provided by alkylated 380 49 benzene component of sulphonic acid. 15 203 834 280 10 I 16 I04 939 99 5 17 203 310 390 20 TABLE 3.

VARIATION OF HYDROXY COMPOUND EXAMPLE T.B.N. of REMARKS ON PRODUCT l-lYDROXY COMPOUND PRODUCT NO. (mg.KOH/g.)

l8 Ethanol 20l Some turbidity l9 n-Propanol 127 Some turbidity 20 i-Propanol Some turbidity 2l n-Butanol 173 Some turbidity 22 i-Butanol 230 Some turbidity 23 's-Butanol 243 Some turbidity TABLE 3.-continued VARIATION OF I-IYDROXY COMPOUND EXAMPLE T.B.N. of REMARKS ON PRODUCT HYDROXY COMPOUND PRODUCT NO. (mg.KOI-I/g.)

24 t-Butanol 257 Some turbidity 25 n-Pentanol 214 Some turbidity 26 Benzyl alcohol 266 Clear and bright 27 Ethylene glycol 205 Clear and bright 28 Propan-I ,2-diol 375 Clear and bright 29 Propan-l,3-diol 306 Clear and bright 3O Di-eth lene glycol. 334 Clear and bright 31 Methyl dioxitol (di-ethy ene glycol monomethyl ether) 300 Clear and bright 32 Ethyl dioxitol (di'ethylene glycol monoethyl ether) 250 Clear and bright 33 Ethylene glycol monomethyl ether 356 Clear and bright 34 Ethylene glycol monoethyl ether 235 Clear and bright TABLE 4.

VARIATION OF AMINE FORMATE PROMOTER 1 PRODUCT EXAMPLE T.B.W.

NO. Amine in Formate Salt Quantity of Amine (mg.HOH/g.) REMARKS 35 1,3-Diamine Propano 12g. 376 Bright and clear, and mobile. 36 3,3-Diamino propylamine 10g. 353 Bright and clear, and mobile. 37 Dimethylamine 15g. 170 Bright and clear. and mobile. 38 Trimethylamino 18g. 81 Hazy. 39 1,6-Diamino hexane 19g. 113 Hazy. 40 Aniline 31 g. 107 Clear and bright. 41 1,2-Diamino benzene 18g. 184 Clear and bright. 42 1,3-Diamino benzene 18g. 140 Dark, but clear and bright. 43 1,4-Diamino benzene 18g. 176 Dark, but clear and bright. 44 Urea 10g. 112 Clear and bright, and mobile.

TABLE 5.

VARIATION OF ACID IN ETHYLENE DIAMINE SALT PRODUCT EXAMPLE Acid in Salt Quantity of Acid T.B.H. REMARKS NO. (mg.KOH/g.)

45 Nitric 21g. 244 Clear and bright. 46 Hydrochloric 12g. 347 47 Boric 7g. 331 48 Palmitic 86g. 381 49 Behenic 113g. 355 50 Benzoic 38g. 275 Carbonation stopped after half an hour due to viscosity increase:

TABLE 6 VARIATION OF ACID IN ETHYLENE DIAMINE SALT PRODUCT EXAMPLE Acid in Salt Quantity of Acid T.B.H. REMARKS NO. mg.I(OI-I/g.)

51 Acetic 10g. 260 High viscosity. 52 Pentanoic 16.5g. 270 High viscosity. 53 Heptanoic 2l.7g. 309 High viscosity. 54 Octanoic 26.0g. 298 High viscosity. 5 5 Iso-octanoic 26.0g. 315 Viscous. 56 Monanoic 29.0 293 Viscous. 57 Decanoic 28. g 316 Viscous. 58 Maleic 9.7g. 192 59 Succinic 9.8g. 188 60 Formic 8.0g. 290 Clear and bright, and mobile.

TABLE 7 COMPARISON OF ETI-IYLENE DIAMINE AND ITS DIFORMATE SALT AS PROMOTER EXAMPLE PROMOTER PREPARATIVE I T.B.H. REMARKS PROCEDURE NO. AND CONDITIONS (mg.KOH/g.)

61 Ethylerbe Diamine Example 3 herein 383 Hazy and viscous.

TABLE 7-continued COMPARISON OF ETHYLENE DlAMlNE AND ITS DlFORMATE SALT AS PROMOTER EXAMPLE PROMOTER PREPARATIVE T.B.H. REMARKS PROCEDURE NO. AND CONDITIONS (mg.KOH/g.)

62 Ethylene Diamine Di- Example 3 herein 402 Clear and bright formate (10g. ethylene diamine 16g. formic acid) 63 Ethylene Diamine Example 11 of US. 263 Hasy.

(20g.) Pat. No.3492230 64 Ethylene Diamine Di- Example 11 of US. 31 1 Clear and bright formatc (20g. ethylene Pat. No.3492230 diamine 32g. formic acid) We claim:

1. In a process for preparing a magnesium overbased lubricant additive wherein a reaction mixture of an oil soluble detergent or dispersant susceptible to overbasing selected from the group consisting of phosphosulphurized hydrocarbons, metal salts of carboxylic acids, sulphonic acids and metal salts of sulphonic acid, a basic magnesium compound in an amount sufficient to overbase said oil soluble detergent or dispersant, and a reaction promoting amount of a hydroxy-containing compound selected from the group consisting of alcohols and monoethers of glycols is formed in an inert solvent, said reaction mixture is contacted with an acidic gas at a reaction temperature of from about 20C up to the decomposition temperature of the reaction mixture and the resultant product is heated to remove volatile components; the improvement comprising: incorporating in said reaction mixture a reaction promoting amount, up to about 40% by weight based on the weight of the inert solvent, of a salt of boric acid and an aliphatic hydrocarbyl diamine or polyamine containing from 2 to 8 carbon atoms.

2. The process of claim 1 wherein the oil soluble detergent or dispersant is present in the amount of about 10 to 150% by weight based on the weight of the inert solvent, the hydroxy containing organic compound is present in an amount of about 5 to 50% by weight, based on the weight of the inert solvent, the salt of the amine and acid is present in the reaction mixture in an amount of about 0.1 to 40% by weight, based on the weight of the inert solvent, about 5 to 50% by weight, based on the weight of the inert solvent, of water is present in the reaction mixture and wherein the acidic gas is carbon dioxide.

3. The process of claim 2 wherein the said salt is a salt of boric acid and an aliphatic hydrocarbyl diamine containing from 2 to 8 carbon atoms.

4. The process of claim 3 wherein the salt is a salt of boric acid and ethylene diamine.

5. The process of claim 1 wherein the basic magnesium compound is magnesium oxide or magnesium hydroxide.

6. The process of claim 1 wherein the inert solvent is a hydrocarbon.

7. The process of claim 1 wherein the hydroxy con taining organic compound is selected from the group consisting of mono-hydroxy alcohols, containing from 1 to 4 carbon atoms, glycols containing from 1 to 4 carbon atoms and monoethers of glycols containing from 1 to 4 carbon atoms.

8. The process of claim 1 wherein the reaction mixture is formed by admixing the inert solvent, the oilsoluble detergent or dispersant, the basic magnesium compound and the hydroxy containing organic compound and thereafter adding thereto an aqueous solution of the amine salt of the acid.

9. The process of claim 1 wherein the basic magnesium compound is present in an amount to provide an additive having a total base number of from about 250 to 500 mg. KOH/g.

10. The process of claim 1 wherein the inert solvent is selected from the group consisting of mineral oils, alkylated benzene and mixtures thereof.

11. The process of claim 1 wherein the inert solvent is a synthetic ester lubricating oil.

12. The process of claim 1 wherein the hydroxy containing organic compound is methanol.

13. The process of claim 1 wherein a non-polar diluent is also included in the reaction mixture.

14. The process of claim 13 wherein the non-polar diluent is selected from the group consisting of xylene, benzene, toluene and petroleum ether.

15. The process of claim 1 wherein from about 10 to 25% by weight, based on the weight of the inert solvent, of water is added to the reaction mixture during treatment of said reaction mixture with carbon dioxide.

16. The process of claim 1 wherein the inert solvent is a hydrocarbon oil solvent, the oil soluble detergent or dispersant is an oil soluble neutral magnesium salt of sulphonic acid in an amount of about 20 to by weight, based on the weight of the hydrocarbon oil solvent; the basic magnesium compound is magnesium oxide or magnesium hydroxide in an amount to provide an additive having a total base number of about 250 to 500 mg. KOl-l/g; the hydroxy-containing compound is methanol in an amount of about 25 to 50% by weight, based on the weight of the hydrocarbon oil solvent; the salt of boric acid and an aliphatic hydrocarbyl diamine is present in an amount of about 0.1 to 15% by weight, based on the weight of the hydrocarbon oil solvent; from about 5 to 50% by weight, based on the weight of the hydrocarbon oil solvent, of water is present in the reaction mixture; and the reaction mixture is treated with carbon dioxide at a temperature of from about 20C up to the reflux temperature of the reaction mixture until the magnesium oxide or magnesium hydroxide is substantially converted to magnesium carbonate.

17. An oil-soluble additive prepared according to the process of claim 1.

18. An oil-soluble additive prepared according to the process of claim 4.

19. An oil-soluble additive prepared according to the process of claim 16.

18 additive according to claim 18.

22. A lubricant comprising a major amount of lubricating oil containing from 0.1 to 10% by weight, based on the total weight of the lubricant, of an oil-soluble additive according to claim 19.

Claims

1. IN A PROCESS FOR PREPARING A MAGNESIUM OVERBASED LUBRICANT ADDITIVE WHEREIN A REACTION MIXTURE OF AN OIL SOLUBLE DETERGENT OR DISPERSANT SUSCEPTIBLE TO OVERBSING SELECTED FROM THE GROOUP CONSISTING OF PHOSPHOSULPHURIZED HYDROCARBONS, METAL SALTS OF CARBOXYLIC ACID, SULPHONIC ACIDS AND METALS SALTS OF SULPHONIC ACID, A BASIS MAGNESIUM COMPOUND IN AN AMOUNT SUFFICIENT TO OVERBASE SAID OIL SOLUBLE DETERGENT OR DISPERSANT, AND A REACTION PROMOTING AMOUNT OF A HYDROXYCONTAINING COMPOUND SELECTED FROM THHE GROUP CONSISTING OF ALCOHOLS AND MONOETHERS OF GLYCOLS IS FORMED IN AN INERT SOLVENT, SAID REACTION MIXTURE IS CONTACTED WITH AN ACIDIC GAS AT A REACTION TEMPERATURE OF FROM ABOUT 20*C UP TO THE DECOMPOSITION TEMPERATURE OF THE REACTION MIXTURE AND THE RESULTANT PRODUCT IS HEATED TO REMOVE VOLATILE COMPONENTS; THE IMPROVEMENT COMPRISING: INCORPORATING IN SAID REACTION MIXTURE A REACTION PROMOTING AMOUNT, UP TO ABOUT 40% BY WEIGHT BASED ON THE WEIGHT OF THE INERT SOLVENT, OF A SALT OF BORIC ACID AND AN ALIPHATIC HYDROCARBYL DIAMINE OR POLYAMINE CONTAINING FROM 2 TO 8 CARBON ATOMS.

6. The process of claim 1 wherein the inert solvent is a hydrocarbon.

7. The process of claim 1 wherein the hydroxy containing organic compound is selected from the group consisting of mono-hydroxy alcohols, containing from 1 to 4 carbon atoms, glycols containing from 1 to 4 carbon atoms and monoethers of glycols containing from 1 to 4 carbon atoms.

8. The process of claim 1 wherein the reaction mixture is formed by admixing the inert solvent, the oil-soluble detergent or dispersant, the basic magnesium compound and the hydroxy containing organic compound and thereafter adding thereto an aqueous solution of the amine salt of the acid.

16. The process of claim 1 wherein the inert solvent is a hydrocarbon oil solvent, the oil soluble detergent or dispersant is an oil soluble neutral magnesium salt of sulphonic acid in an amount of about 20 to 120% by weight, based on the weight of the hydrocarbon oil solvent; the basic magnesium compound is magnesium oxide or magnesium hydroxide in an amount to provide an additive having a total base number of about 250 to 500 mg. KOH/g.; the hydroxy-containing compound is methanol in an amount of about 25 to 50% by weight, based on the weight of the hydrocarbon oil solvent; the salt of boric acid and an aliphatic hydrocarbyl diamine is present in an amount of about 0.1 to 15% by weight, based on the weight of the hydrocarbon oil solvent; from about 5 to 50% by weight, based on the weight of the hydrocarbon oil solvent, of water is present in the reaction mixture; and the reaction mixture is treated with carbon dioxide at a temperature of from about 20*C up to the reflux temperature of the reaction mixture until the magnesium oxide or magnesium hydroxide is substantially converted to magnesium carbonate.

17. An oil-soluble additive prepared according to the process of claim 1.

18. An oil-soluble additive prepared according to the process of claim 4.

19. An oil-soluble additive prepared according to the process of claim 16.

20. A lubricant comprising a major amount of lubricating oil containing from 0.1 to 10% by weight, based on the total weight of the lubricant, of an oil-soluble additive according to claim 17.

21. A lubricant comprising a major amount of lubricating oil containing from 0.1 to 10% by weight, based on the total weight of the lubricant, of an oil-soluble additive according to claim 18.