NO168536B - LUBRICANT PREPARATION AND MANUFACTURING THEREOF. - Google Patents

Description

The present invention relates to a lubricant preparation comprising a main quantity of an oil with lubricant viscosity and a smaller quantity of an oil-soluble preparation.

The invention also relates to a method for producing this lubricant preparation.

Various preparations produced by sulphurisation of olefins and olefin-containing compounds are known in the art, as are lubricants containing these products. Typical sulfurized preparations prepared by reacting olefins such as isobutene, diisobutene and triisobutene, with sulfur under various conditions, are described in, for example, "Chemical Review", 65, 237 (1965). Other references describe the reaction of such olefins with hydrogen sulfide to form predominantly mercaptans where sulfides, disulfides and higher polysulfides are also formed as by-products. Reference should be made to "J. Am. Chem. Soc.", 60, 2452 (1938) as well as US-PS 3,419,614. The patent describes a method for increasing the yield of mercaptan by carrying out the reaction between olefin and hydrogen sulphide and sulfur at high temperature in the presence of various basic substances.

It is also known that Diels-Alder adducts can be sulfurized to form sulfur-containing preparations which are particularly useful as extreme pressure and antiwear additives in various lubricating oils. US-PS 3,632,566 and US-Reissue 27,331 describe such sulfurized Diels-Alder adducts and lubricants containing them. These patents describe the ratio of sulfur:Diels-Alder adduct to a molar ratio of 0.5:1 to 10.0:1. The patents indicate that it is usually desirable to incorporate as much stable sulfur into the compound as possible, and therefore a molar excess of sulfur is usually used. The described lubricating preparations may contain other additives which are usually used to improve the properties of lubricating preparations such as dispersants, detergents, extreme pressure agents, and further oxidation and corrosion inhibiting agents. For some lubrication applications, however, the sulfur-containing preparations described above have not proven to be completely sufficient as multi-purpose additives.

Organophosphorus and metal organophosphorus compounds are used extensively in lubricating oils as extreme pressure agents and antiwear agents. Examples of such compounds are: phosphosulphured hydrocarbons such as the reaction product between a phosphorus sulphide and turpentine; phosphorous esters including dihydrocarbyl and trihydrocarbyl phosphites; and metal phosphorodithioates such as zinc dialkyl phosphorodithioates. Due to toxicological problems associated with the use of organo-phosphorus compounds and especially with metal dialkyl phosphorodithioates, there is a need to develop lubricant preparations which contain lower levels of phosphorus, and which are nevertheless characterized by having acceptable oxidation, inhibition and anti-wear properties. Lubricants containing low levels of phosphorus are also desirable in view of the tendency of phosphorus to poison catalytic converters used to control emissions from gasoline engines.

Polyvalent metal salts of dithiocarbamic acids are known and have been described as useful oil additives because they serve a dual function, namely sequestering unwanted components in the oil and because they act as antioxidants. Lubricating oil preparations are described as extensive combinations of

-various polyvalent metal dithiocarbamates with other chemical additives that exhibit desirable property-enhancing characteristics when added to the lubricating oils in combination with the dithiocarbamates. For example, US-PS 2,999,813 describes a lubricating composition comprising a sulfurized mineral oil and a polyvalent metal dithiocarbamate. Preferably, the preparation also includes a lead soap of a naphthenic fatty acid. The production of lubricating preparations comprising mineral oil, metal salts of dithiocarbamic acids and coupling agents such as alcohols, esters, ketones and other stable

oxygen-containing substances, is described in US-PS 2,265,851. US-PS 2,394,536 describes lubricating oil preparations containing the combination of organic sulphides and salts of dithiocarbamic acids. Organic sulfides are generally represented by the formula P»l(s)nR2 where R^ and R£ are allphatic groups and n is 1, 2 or 3.

US-PS 2,805,996 describes the use of amine thiocarbarnate complexes in lubricating oil preparations, and US-PS 2,947,695 describes the advantages of using mixtures of polyvalent metal dithiocarbamates in the manufacture of oil-soluble additive preparations which can be used in the manufacture of lubricating oil.

The present invention aims to improve the known technique and thus relates to a lubricant preparation of the type mentioned at the outset and this lubricant which is characterized by the fact that it comprises:

(A) at least one metal salt of at least one dithiocarbamic acid of the formula

where Rj and R2 are each independently hydrocarbyl groups or together form polymethylene or alkyl-substituted polymethylene groups where the total number of carbon atoms in R^ and R2 is sufficient to make the metal salt oil-soluble, and

(B) at least one oil-soluble sulfurized Diels-Alder adduct of at least one dienophile with at least one aliphatic conjugated diene

wherein the sulfurized adduct comprises the reaction product of sulfur and Diels-Alder adducts in a molar ratio of less than 1:1;

where the weight ratio A:B lies within the range 1:10 to 50:1 and where further the lubricant preparation contains less than 0.1 weight-3t of phosphorus.

As mentioned, the invention also relates to a method for producing such a lubricating oil preparation and this is characterized by the fact that it comprises combining a larger amount of an oil with lubricant viscosity with a smaller amount of an oil-soluble preparation comprising:

(A) at least one metal salt of at least one dithiocarbamic acid of the formula

where R 1 and R 2 are each independently hydrocarbyl groups or together form polymethylene or alkyl-substituted polymethylene groups where the total number of carbon atoms in R 1 and R 2 is sufficient to make the metal salt oil-soluble, and

(B) at least one oil-soluble sulfurized Diels-Alder adduct of at least one dienophile with at least one aliphatic conjugated diene

wherein the sulfurized adduct comprises the reaction product of sulfur and Diels-Alder adducts in a molar ratio of less than 1:1;

where the weight ratio A:B lies within the range 1:10 to 50:1 and where further the lubricant preparation contains less than 0.1 weight-# phosphorus.

The sulfurized Diels-Alder adduct is generally prepared by reacting sulfur and a Diels-Alder adduct in a molar ratio of between 0.5:1 and 10:1 where the adduct is an adduct of at least one dienophile with at least one aliphatic or alicyclic conjugate the day. Additive concentrates and lubricating oil preparations containing the oil-soluble preparations according to the invention are also described. The oil-soluble preparations according to the invention are usable especially in lubricating oil formulations which contain little or no phosphorus.

The hydrocarbyl groups Rj and R2 in component (A) can be alkyl groups, cycloalkyl groups, aryl groups, alkaryl groups or aralkyl groups. R 1 and R 2 taken together may represent the group consisting of polymethylene and alkyl substituted polymethylene groups to thereby form a cyclic compound with nitrogen. In general, the alkyl group will contain at least two carbon atoms. The metal in the metal salt can be a monovalent metal or a polyvalent metal, although polyvalent metals are preferred because it is generally difficult to prepare oil solutions containing the desired amounts of alkali metal salts. Suitable polyvalent metals are, for example, the alkaline earth metals, zinc, cadmium, magnesium, tin, molybdenum, iron, copper, nickel, cobalt, chromium, lead and so on. The Group II metals are preferred.

When choosing a metal salt of a dlthiocarbamic acid to be used in the oil-soluble preparations according to the invention, Ri, R2 and the metal can be varied as long as the metal is sufficiently oil-soluble. The nature and type of the mineral base raw material and the type of service desired for the treated lubricating oil are important modifying factors in the choice of metal salt.

Mixtures of the metal salts of dithiocarbamic acids are also considered useful according to the present invention. Such mixtures can be prepared by first preparing mixtures of dithiocarbamic acids and then converting these acids to metal salts or alternatively preparing metal salts of different dithiocarbamic acids and then mixing these to give the desired products. Thus, the mixtures that can be incorporated into the preparations according to the invention can be mere physical mixtures of the different metallic dithiocarbamine compounds or different dithiocarbamide groupings bound to the same polyvalent metal atom.

Examples of alkyl groups are ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, decyl, dodecyl, tridecyl, pentadecyl and hexadecyl groups including isomeric forms thereof. Examples of cycloalkyl groups are cyclohexyl and cycloheptyl groups, and examples of aralkyl groups are benzyl and phenylethyl. Examples of polymethylene groups are penta- and hexamethylene groups, and examples of alkyl-substituted polymethylene groups are methylpentamethylene, dimethylpentamethylene and so on.

Specific examples of the metal dithiocarbamates that can be used as component (A) in the preparations according to the invention are zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, zinc di(2-ethylhexyl)dithiocarbamate, cadmium dibutyldithiocarbamate, cadmium dioctyldithiocarbamate, cadmium octylbutyldithiocarbamate, magnesium dibutyldithiocarbamate, magnesium dioctylthiocarbamate, sodium diamyldithiocarbamate, sodium diisopropyldithiocarbamate and so on.

The various metal salts of dithiocarbamic acids used in the preparations according to the invention are well known in this technique and can be prepared by known techniques.

Component (B) in the oil-soluble preparations according to the invention comprises at least one oil-soluble sulfurized Diels-Alder adduct of at least one dienophile with at least one aliphatic conjugated diene. The sulphurised Diels-Alder adducts can be produced by reacting various sulphurisation agents with the Diels-Alder adducts as described in more detail below. Preferably, the sulfurizing agent is sulfur.

The Diels-Alder adducts are a well-known class of components produced by diene synthesis or a Diels-Alder reaction. A summary of the prior art in connection with this class of compounds can be found in the Russian monograph, "Dienovyi Sintes, Izdatelstwo Akademii Nauk" SSSR, 1963 by A.S. Onischenko. (Translated into English by L. Mandel as A.S Onischenko", Diene Synthesis", N.Y., Daniel Davey and Co., Inc., 1964).

In principle, the diene synthesis (Diels-Alder reaction) involves the reaction of at least one conjugated diene, >C-C-C-C<, with at least one ethylenic or acetylenic unsaturated compound, >C-C> or -C«=C-, these latter compounds being known as dienophiles. The reaction can be represented as follows:

Reaction 1:

React. loan 2:

The products A and B are usually called Diels-Alder adducts. It is these adducts that are used as starting materials for the production of the sulphurised Diels-Alder adducts that are used according to the invention.

Representative examples of 1,3-dienes are aliphatic and alicyclic conjugated diolefins or dienes of the formula

wherein R to R^ are each independently selected from halogen, alkyl, halogen, alkoxy, alkenyl, alkenyloxy, carboxy, cyano, amino, alkylamino, dialkylamino, phenyl, and phenyl substituted with 1 to 3 substituents corresponding to R to R<5> provided that a pair of R's on adjacent carbon atoms does not form an additional double bond in the diene, or R, R<2>, R<3> and R<5> are as defined and R<1> and R<4 > are alkylene groups bonded together to form a ring including the nitrogen atom. Preferably, R is not more than three of the R variables different from hydrogen and at least one is hydrogen. Usually the total carbon content in the diene will not exceed 20. In a preferred feature of the invention, adducts are used where R<2> and R<3> are both hydrogen and at least one of the remaining R variables is also hydrogen. Preferably, the carbon content of these R variables when different from hydrogen is 7 or less. In this most preferred class, those dienes in which R, R<1>, R<4> and R<5> are hydrogen, chlorine or lower alkyl are particularly useful. Special examples of R variables are the following groups: methyl, ethyl, phenyl, H00C-, N-C-, CH3O-, CH3COO-, CH3CH20-, CH3C(0)-, HC(0)-, Cl, Br, tert- butyl, CF3, tolyl and so on. Piperylene, isoprene, methylisoprene, chloroprene and 1,3-butadiene are among the preferred dienes for use in the preparation of the Diels-Alder adducts.

In addition to these linear 1,3-conjugated dienes, cyclic dienes are also useful as reactants in the formation of the Diels-Alder adducts. Examples of these cyclic dienes are cyclopentadienes, fulvenes, 1,3-cyclohexadelenes, 1,3-cycloheptadienes, 1,3,5-cycloheptatrilenes, cyclooctatetraene and 1,3,5-cyclononatrienes. Various substituted derivatives of these compounds enter the diene syntheses.

The dienophiles which are calculated for reaction with the above-mentioned dienes to form the adducts used as reactants can be represented by the formula

where the K variables are the same as the R variables in formula II because it is possible that a pair of K variables can form a further carbon-carbon bond, that is K-C=C-K2, but does not necessarily do this.

A preferred class of dienophiles are those in which at least one of the K variables is selected from electron-accepting groups such as formyl, cyano, nitro, carboxy, carbohydrocarbyloxy, hydrocarbylcarbonyl, hydrocarbylsulfonyl, carbamyl, alkylcarbamyl, N-acyl-N-hydrocarbylcarbamyl, N-hydrocarbylcarbamyl and N,N-dihydrocarbylcarbamyl. The K variables that are not electron-accepting groups are hydrogen, hydrocarbyl or substituted hydrocarbyl groups. Generally, hydrocarbyl and substituted hydrocarbyl groups will not contain more than 10 carbon atoms each.

The hydrocarbyl groups present as N-hydrocarbyl substituents are preferably alkyl of 1 to 30 carbon atoms and especially 1 to 10 carbon atoms. Representative of this class of dienophiles are the following: nitroalkanes, for example 1-nitrobutene-1, 1-nitropene-1, 3-methyl-1-nitrobutene-1, 1-nitroheptene-1, 1-nitrooctene-1, 4-ethoxy -1-nitrobutene-1; a,<p->ethylenically unsaturated aliphatic carboxylic acid esters, for example acrylates and a-methylalkyl acrylates (for example alkyl methacrylates) such as butyl acrylate and butyl methacrylate, decyl methacrylate, di-(n-butyl) maleate, di-(t-butyl maleate); acrylonitrile, methacrylonitrile, p<->nitrostyrene, methyl vinyl sulfone, acrolein, acrylic acid; cx ,P-ethylenically unsaturated aliphatic carboxylic acid amides, for example acrylamide, N,N-dibutylacrylamide, methacrylamide, N-dodecyl methacrylamide, N-pentylcrotonamide; crotonaldehyde, crotonic acid, p,p-dimethyl-divinyl ketone, methyl-vinyl ketone, N-vinylpyrrolidone, alkyl halides and the like.

A preferred class of dienophiles are those in which at least one but not more than two K variables are -C(0)0-Ro where RQ is the residue of a saturated aliphatic alcohol of up to 40 carbon atoms; for example, at least one K is carbohydrocarbyloxy such as carboethoxy, carbobutoxy and so on, the aliphatic alcohol from which -RQ is derived may be a mono- or polyhydroxy alcohol such as alkylene glycols, alkanols, aminoalkanols, alkoxy-substituted alkanols, ethanol, ethoxyethanol, propanol, p< ->diethylaminoethanol, dodecyl alcohol, diethylene glycol, tripropylene glycol, tetrabutylene glycol, hexanol, octanol, isooctyl alcohol and the like. In this particularly preferred class of dienophiles, no more than two K variables will be -C(0)-O-Ro groups and the remaining K variables will be hydrogen or lower alkyl, for example methyl, ethyl, propyl, isopropyl and the like .

Specific examples of dienophiles of the type discussed above are those in which at least one of the K variables is one of the following groups: hydrogen, methyl, ethyl, phenyl, H00C-, HC(0)-, CH2-CH-, HG -- HOG-, CH3C(0)0-, C1CH2-, H0CH2-, α-pyridyl, -NO2, Cl, Br, propyl, iso-butyl and so on.

In addition to the ethylenically unsaturated dienophiles, there are many usable acetylenically: unsaturated dienophiles such as propiolaldehyde, methylethynyl ketone, propylethynyl ketone, propenylethynyl ketone, propiolic acid, propiolic acid nitrile, ethyl propiolate, tetrolic acid, propargyl aldehyde, acetylene dicarboxylic acid, the dimethyl ester of acetylene dicarboxylic acid, dibenzoylacetylene and the like. Cyclic dienophiles include cyclopentendlone, coumarin, 3-cyanocoumarin, dimethylmaleic anhydride, 3,6-endomethylene-cyclohexendylcarboxylic acid and so on. With the exception of the unsaturated dicarboxylic anhydrides derived from linear dicarboxylic acids (eg, maleic anhydride, methylmaleic anhydride, chloromaleic anhydride), this class of cyclic dienophiles is limited in commercial utility due to limited availability or other economic considerations.

The reaction products of these dienes and dienophiles correspond to the general formulas where R to R<5> and K to K3 are as defined above. If the dienof The moiety entering the reaction is acetylenic instead of ethylenic, two of the K variables, one from each carbon atom, form another carbon-carbon double bond. Where the diene and/or dienophile is itself cyclic, the adduct will obviously become bicyclic, tricyclic, condensed and so on, as exemplified below:

Reaction 3:

Reaction 4:

Typically, the adducts involve reaction between equimolar amounts of diene and dienophile. However, if the dienophile has more than one ethylenic bond, it is possible for additional diene to react if present in the reaction mixture.

The adducts and the processes for producing the adducts shall be further exemplified by the examples below. Unless otherwise indicated in these examples and in other parts of the description and in the claims, all parts and percentages are by weight.

EXAMPLE A

A mixture comprising 400 parts toluene and 66.7 parts aluminum chloride is charged to a two liter flask equipped with a stirrer, nitrogen inlet tube, and a solid carbon dioxide cooled reflux condenser. A second mixture comprising 640 parts or 5 moles of butyl acrylate and 240.8 parts of toluene is added to the AlCl 3 slurry while maintaining the temperature within the range of 37-58°C over a period of fifteen minutes. Then 313 parts or 5.8 moles of butadiene are added to the slurry over a period of two hours and three quarters while maintaining the temperature in the reaction mass at 50-61°C by means of external cooling. The reaction mass is blown with nitrogen for approx. 20 minutes and then transferred to a four-liter separatory funnel and washed with a solution of 150 parts concentrated hydrochloric acid in 1100 parts water. The product is then subjected to two additional water washes using 1,000 parts of water per washing. The washed reaction product is then distilled to remove unreacted butyl acrylate and toluene. The residue from this first distillation step is subjected to further distillation at a pressure of 9-10 mm of mercury, after which 785 parts of the desired product are collected over the temperature range 105-115°C.

EXAMPLE B

The adduct of isoprene and acrylonitrile is prepared by mixing 136 parts of isoprene, 106 parts of acrylonitrile and 0.5 parts of hydroquinone (polymerization inhibitor) in a cradle autoclave and is then heated for 16 hours at a temperature within the range of 130-140°C. The autoclave is vented and the contents are decanted, whereby 240 parts of a pale yellow liquid are produced. This is stripped at a temperature of 90° C and a pressure of 10 mm Hg and the desired liquid product is obtained as a residue.

EXAMPLE C

Using the procedure in Example B, 136 parts of isoprene, 172 parts of methyl acrylate and 0.9 parts of hydroquinone are converted to the isoprene-methyl acrylate adduct.

EXAMPLE D

By following procedure 1 example B, 104 parts of liquefied butadiene, 166 parts of methyl acrylate and 1 part of hydroquinone are charged to the cradle auto oven and heated to 130-135°C for 14 hours. The product is then decanted and stripped, thereby obtaining 237 parts of the adduct.

EXAMPLE E

The adduct of isoprene and methyl methacrylate is prepared by reacting 745 parts of isoprene with 1095 parts of methyl methacrylate in the presence of 5.4 parts of hydroquinone in the cradle autoclave by following the procedure according to example B above. 1490 parts of the adduct are recovered.

EXAMPLE F

The adduct of butadiene and dibutyl maleate in an amount of 810 parts is prepared by reacting 915 parts of dibutyl maleate, 216 parts of liquefied butadiene and 3.4 parts of hydroquinone in the cradle autoclave according to Example B.

EXAMPLE G

A reaction mixture comprising 378 parts of butadiene, 778 parts of N-vinylpyrrolidone, and 3.5 parts of hydroquinone is added to a cradle autoclave pre-cooled to -35°C. The autoclave is then heated to a temperature of 130-140° C for approx. 15 hours. After aeration, decantation and stripping of the reaction mass, 75 parts of the desired adduct are obtained.

EXAMPLE H

By following the technique in example B, 270 parts of liquefied butadiene, 1060 parts of isodecyl acrylate and 4 parts of hydroquinone are reacted in the cradle autoclave at a temperature of 130-140°C for approx. 11 hours. After decantation and stripping, 1136 parts of the adduct are obtained.

EXAMPLE I

By following the same general procedure as Example A, 132 parts (2 mol) of cyclopentadiene, 256 parts (2 mol) of butyl acrylate and 12.8 parts of aluminum chloride are reacted to obtain the desired adduct. The butyl acrylate and aluminum chloride are first added to a 2 liter flask equipped with a stirrer and reflux condenser. While heating the reaction mass to a temperature within the range of 59-52°C, cyclopentadiene is added to the flask over a period of half an hour. The reaction mass was then heated for approx. 7.5 hours at a temperature of 95-100°C. The product is washed with a solution containing 400 parts water and 100 parts concentrated hydrochloric acid and the aqueous layer is discarded. Then 1500 parts of benzene are added to the reaction mixture and the benzene solution is washed with 300 parts of water and the aqueous phase is removed. The benzene is removed by distillation and the residue is stripped at 0.2 mm Hg to recover the adduct as a distillate.

EXAMPLE J

By following the technique in Example B, the adduct of butadiene and allyl chloride is prepared using two moles of each reactant.

EXAMPLE K

139 parts (or 1 mol) adduct of butadiene and methyl acrylate is transesterified with 158 parts or 1 mol of decyl alcohol. The reactants are added to a reaction flask and 3 parts sodium methoxide are added. The reaction mixture is then heated to a temperature of 190-200°C for 7 hours. The reaction mass is washed with a 10% sodium hydroxide solution, after which 250 parts of naphtha are added. The naphtha solution is washed with water. After complete washing, 150 parts of toluene are added and the reaction mass is stripped at 150°C under a pressure of 28 mm Hg. A dark brown fluid product is recovered in a quantity of 225 parts. This product is fractionated under reduced pressure, resulting in the recovery of 178 parts of a product boiling in the range of 130-133°C at a pressure of 0.45 to 0.6 mm Hg.

EXAMPLE L

The general procedure in Example A is repeated except that only 270 parts or 5 moles of butadiene are incorporated into the reaction mixture.

The sulfur-containing compounds of the invention are readily prepared by heating a mixture of a sulfurizing agent such as sulfur, and at least one of the Diels-Alder adducts of the types discussed above, at a temperature in the range of 110°C to just below the Diels decomposition temperature -The age adducts. Temperatures in the range of 110 to 200°C will usually be used. This reaction results in a mixture of products, some of which have been identified. In the compounds of known structure, the sulfur reacts with the substituted unsaturated cycloaliphatic reactants at a double bond in the nucleus of the unsaturated reactant.

The molar ratio between sulfur and Diels-Alder adduct used in the preparation of the sulfur-containing preparation is from 0.5:1 to 10:1f, although the molar ratio will usually be less than 4:1. In one embodiment of the invention, the molar ratio is less than 1.7:1 and most preferably less than 1:1.

The sulfurization reaction can be carried out in the presence of suitable inert solvents such as mineral oils, alkanes of 7 to 18 carbon atoms and so on, although no solvent is generally required. After completion of the reaction, the reaction mass can be filtered and/or subjected to other conventional cleaning techniques. There is no need to separate the different sulfur-containing products as they can be used in the form of a reaction mixture comprising compounds of known and unknown structure.

As the hydrogen sulphide is an unwanted pollutant, it is advantageous to use standard procedures to support the removal of H2S from the products. Blowing with steam, alcohols, air or nitrogen supports the removal of ItøS in the same way as heating under reduced pressure with or without blowing. It is sometimes advantageous to incorporate substances which are usable as sulphurisation catalysts into the reaction mixture. These substances can be acidic, basic or neutral. Useful neutral and acidic substances are acidified clays such as "Super Filtrol", p-toluenesulfonic acid, dialkyl phosphorodithionic acids, phosphorus sulfides such as phosphorus pentasulfide and phosphites such as triaryl phosphites, for example triphenyl phosphite.

The basic substances can be inorganic oxides and salts such as sodium hydroxide, calcium oxide and sodium sulphide. However, the most desirable basic catalysts are nitrogen bases including ammonia and amines. The amines can be primary, secondary and tertiary hydrocarbylamines in which the hydrocarbyl residues are alkyl, aryl, aralkyl, alkaryl and the like and contain 1-20 carbon atoms. Suitable amines include aniline, benzylamine, dibenzylamine, dodecylamine, naphthylamine, tallamines, N-ethyldipropylamine, N-phenylbenzylamine, N,N-diethylbutylamine, m-toluidine and 2,3-xylidine. Also useful are heterocyclic amines such as pyrrolidine, N-methylpyrrolidine, piperidine, pyridine and quinoline.

The preferred basic catalysts are ammonia and primary, secondary or tertiary alkylamines with 1-8 carbon atoms in the alkyl residues. Representative amines of this type are methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, di-n-butylamine, tri-n-butylamine, tri-sec-hexylamine and tri-n-octylamine. Mixtures of these amines can be used in the same way as mixtures of ammonia and amines.

When a catalyst is used, the amount is generally 0.05-2.0% by weight of the adduct.

The following examples illustrate the preparation of the new sulfur-containing compounds which can be used according to the invention.

EXAMPLE I

To 255 parts or 1.65 mol of the isoprene acrylate adduct from Example C, heated to a temperature of 110-120°C, is added 53 parts or 1.65 mol of sulfur over a 45 minute period. The heating continues for 4.5 hours to a temperature within the range of 130-160°C. After cooling to room temperature, the reaction mixture is filtered through a medium sintered glass funnel. The filtrate consists of 301 parts of the desired sulfur-containing products.

EXAMPLE II

A reaction mixture comprising 1175 parts or 6 moles of the Dlels-Alder adduct of butyl acrylate and Isoprene as well as 192 parts or 6 moles of sulfur is heated for 0.5 hours to 108-110°C and then to 155-165°C for 6 hours under simultaneous bubbling nitrogen through the reaction mixture in an amount of 0.007 to 0.014 standard m<5> per hour. At the end of the heating period, the reaction mixture is allowed to cool and it is then filtered at room temperature. The product is then allowed to stand for 24 hours, after which it is refiltered. The filtrate is the desired product.

EXAMPLE III

4.5 mol of sulfur and 4.5 mol of the adduct of isoprene-methyl methacrylate are mixed at room temperature and heated for one hour to 110°C while simultaneously blowing nitrogen through the reaction mass in an amount of 0.007-0.014 standard m<5> per hour. The temperature of the reaction mixture is then raised to 150-155°C for 6 hours while maintaining the nitrogen blowing. After heating, the reaction mixture is allowed to stand for a few hours while cooling to room temperature, after which it is filtered. The filtrate consists of 842 parts of the desired sulfur-containing product.

EXAMPLE IV

A one liter flask equipped with a stirrer, reflux condenser, condenser and a nitrogen inlet is charged with 256 parts or 1 mole of the adduct of butadiene and isodecyl acrylate and 51 grams or 1.6 moles of sulfur and then heated for 1 12 hours, allowed to stand for 21 hours and is filtered at room temperature whereby the desired product is obtained as a filtrate.

EXAMPLE V

A mixture of 1703 parts or 9.4 moles of a butyl acrylate-butadiene adduct as prepared in Example L, 280 parts or 8.8 moles of sulfur and 17 parts of triphenyl phosphite is prepared in a reaction vessel and gradually heated over 2 hours to a temperature to approx. 185°C under stirring and purging with nitrogen. The reaction is exothermic near 160-170°C and the mixture is kept at approx. 185°C for 3 hours. The mixture is cooled to 90°C over a period of 2 hours and filtered using a filter aid. The filtrate is the desired product and contains 14.056 sulfur.

EXAMPLE VI

The procedure of Example V is repeated except that triphenyl phosphite is omitted from the reaction mixture.

EXAMPLE VII

The procedure in Example V is repeated except that the triphenyl phosphite is replaced with 2.0 parts of triamylamine as sulphurisation catalyst.

EXAMPLE VIII

A mixture of 547 parts of a butyl acrylate-butadiene adduct, prepared as in example L, as well as 5.5 parts triphenylphosphite, is prepared in a reaction vessel and heated with stirring to a temperature of approx. 50°C after which 94 parts of sulfur are added over a period of 30 minutes. The mixture is heated to 150°C for 3 hours while flushing with nitrogen. The mixture is then heated to approx. 185°C for approx. 1 hour. The reaction is exothermic and the temperature is kept at approx. 185 °C by using a cold water jacket during approx. 5 hours. At this point, the contents of the reaction vessel are cooled to 85°C and 33 parts of mineral oil are added. The mixture is filtered at this temperature and the filtrate is the desired product in which the ratio of sulphur: adduct is 0.98:1.

EXAMPLE IX

The general procedure of Example 8 except that triphenyl phosphite is not incorporated into the reaction mixture.

EXAMPLE X

A mixture of 500 parts or 2.7 moles of a butyl acrylate-butadiene adduct as prepared in Example L and 109 parts or 3.43 moles of sulfur is prepared and heated to 180°C and maintained at a temperature of 180-190°C in about. 6.5 hours. The mixture is cooled while blowing with nitrogen to remove hydrogen sulphide odour. The reaction mixture is filtered and the filtrate is the desired product containing 15.8% sulfur.

EXAMPLE XI

A mixture of 728 parts or 4.0 moles of a butyl acrylate-butadiene adduct as prepared in Example L, 218 parts or 6.8 moles of sulfur and 7 parts of triphenylphosphite is prepared and heated with stirring to a temperature of approx. 181°C in 1.3 hours. The mixture is kept under nitrogen purging at a temperature of 181-187°C for 3 hours. After the material has cooled to approx. 85° C. during 1.4 hours, the mixture is filtered using a filter aid and the filtrate is the desired product containing 23.1$.

EXAMPLE XII

A mixture of 910 parts or 5 moles of a butyl acrylate-butadiene adduct as prepared in Example L, 208 parts or 6.5 moles of sulfur and 9 parts of triphenyl phosphite is prepared and heated with stirring and nitrogen blowing to a temperature of approx. 140°C for 1.3 hours. Heating is continued to raise the temperature to 187°C over 1.5 hours and the material is held at 183-187°C for 3.2 hours. After cooling the mixture to 89°C, the mixture is filtered with a filter aid and the filtrate is the desired product containing 18.2% sulphur.

EXAMPLE XIII

A mixture of 910 parts or 5 moles of a butyl acrylate-butadiene adduct prepared as in Example L, 128 parts or 4 moles of sulfur and 9 parts of triphenyl phosphite is prepared and heated with stirring under a sweep of nitrogen to a temperature of 142°C During approx. . 1 hour. Heating is continued to raise the temperature to 185-186°C over 2 hours and the mixture is held at 185-187°C for 1 3.2 hours. After the reaction mixture is cooled to 96°C, it is filtered with filter aid and the filtrate is then the desired product containing 12% sulphur.

EXAMPLE XIV

The general procedure of Example XIII is repeated except that the mixture contains 259 parts or 8.09 moles of sulfur. The product thus obtained contains 21.7% of sulphur.

EXAMPLE XV

A reaction mixture comprising 1175 grams or 6 moles of the Diels-Alder adduct of butyl acrylate and isoprene as well as 384 grams or 12 moles of sulfur flower is heated for 0.5 hours to 108-110°C and then to 155-165°C for 6 hours while nitrogen gas is bubbled through the reaction mixture in an amount of 0.007 to 0.014 standard m<*> per hour. At the end of the heating period, the reaction mixture is allowed to cool and it is filtered at room temperature. The product is then allowed to stand for 24 hours and filtered again. The filtrate weighing 1278 grams is the desired product.

EXAMPLES XVI-XX

Examples XVI to XX illustrate the preparation of other sulfur-containing compounds which can be used according to the invention. In each case, the adduct and sulfur are mixed in a reaction flask and then heated to a temperature in the range of 150-160°C for a period of 7 to 10 hours with nitrogen bubbling through the reaction mixture. The sulphurised product is then allowed to cool to room temperature and it is set aside for a few hours. The reaction mass is then filtered and the filtrate represents the desired sulfur-containing products.

It has been found that if the sulfur-containing products according to the invention are treated with an aqueous solution of sodium sulphide containing from 5 to 75% by weight of Na 2 S, the treated product may show a lesser tendency to darken freshly polished copper.

The treatment involves mixing sulphurised reaction product and sodium sulphide solution for a period of time sufficient for all unreacted sulfur to be captured, usually a period of a few minutes to several hours depending on the amount of unreacted sulphur, the amount and concentration of the sodium sulphide solution. The temperature is not critical but will usually lie within the range of 20 to 100°C. After the treatment, the resulting aqueous phase is separated from the organic phase by conventional techniques, i.e. decantation and so on. Other alkali metal sulfides M2SX where M is an alkali metal and x is 1, 2 or 3 can be used to capture unreacted sulfur but those where x is greater than 1 are not nearly as effective. Sodium sulphide solutions are preferred for economic and efficiency reasons. This procedure is described in greater detail in US-PS 3,498,915.

It has also been established that treatment of the reaction products with solid, insoluble acidic substances such as acidified clays or acid resins and subsequent filtration of the sulfurized reaction mixture improves the products with regard to color and solubility characteristics. Such treatment comprises thorough mixing of the reaction mixture with from 0.1 to 10% by weight of the solid acidic material at a temperature of 25-150°C and subsequent filtration of the product.

As previously indicated, there is no need to separate the sulfur-containing products produced by this reaction. The reaction product is a mixture that includes compounds whose structures have been determined but which also includes compounds whose structures are unknown. Because it is not economically feasible to separate the components in the reaction mixtures, they are used in combination as a mixture of sulfur-containing compounds.

In order to remove the last traces of impurities from the reaction mixture, especially when the adduct produced was prepared using a Lewis acid catalyst, for example AICI3, it is sometimes desirable to add an organic inert solvent to the liquid reaction product and, after thorough mixing , to filter it all over again. The solvent is then stripped from the product. Suitable solvents include solvents of the type mentioned above such as benzene, toluene and the higher alkanes and so on. A particularly useful class of solvents is textile spirits.

In addition, other conventional cleaning techniques can be used with advantage when cleaning sulphurised products which are used according to the invention. For example, commercial filter aids can be added to the materials prior to filtration to increase filtration efficiency. Filtration through diatomaceous earth is particularly useful where the intended use requires the removal of essentially all solids. However, this is a well-known technique for the person skilled in the art and shall not be elaborated further.

The relative amounts of the metal salts of dithiocarbamic acid, component (A), and the sulfurized Diels-Alder adduct, component (B), may vary within ranges depending on the desired use of the preparation. In general, the weight ratio between the metal salt (A) and the sulfurized adduct (B) is in the range 1:10 to 50:1. The exact quantities for the two components to be incorporated in the formulations according to the invention can be easily determined by the person skilled in the art.

The preparations according to the invention comprising components (A) and (B) are usable in lubricating oil mixtures. The preparations can be added directly to the lubricant. Preferably, however, they are diluted with a substantially inert, usually liquid organic diluent such as mineral oil, naphtha, benzene, toluene or xylene to form an additive concentrate. These additives usually contain from 20 to 90% by weight of the preparations and may additionally contain one or more other additives which are known in this technique and described below. The rest of the concentrate is essentially inert and usually liquid diluent.

The preparations according to the invention are useful for improving the properties of lubricants containing little or no phosphorus, especially lubricants containing less than 0.1% phosphorus. In such low-phosphorus lubricants, it is preferred to use a sulphurised Diels-Alder adduct, component (B), which is produced by reacting sulfur with an adduct 1 in a molar ratio of less than 1:1.

The lubricating oil mixtures comprise a main quantity of an oil with a lubricating viscosity including natural and synthetic lubricating oils, as well as mixtures thereof.

Natural oils include animal oils and vegetable oils (for example, castor oil and lard oil), as well as mineral lubricating oil such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic, or mixed paraffinic naphthenic type. Oils with lubricant viscosity derived from coal or shale can also be used. Synthetic lubricating oils are hydrocarbon oils and halogen-substituted ones, such as polymerized and interpolymerized olefins (for example, polybutylenes, polypropylenes, propylene isobutylene copolymers, chlorinated polybutylenes, and so on); poly(1-hexenes), poly(1-octenes), poly(1-decenes) and so on and mixtures thereof; alkylbenzenes (for example dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)-n-benzenes and so on); polyphenyls (eg, biphenyls, terphenyls, alkylated polyphenyls, and so on); alkylated diphenyl ethers and alkylated diphenyl sulphides and derivatives, analogues and homologues thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof in which the terminal hydroxyl groups have been modified by esterification, etherification and so on, constitute another class of known synthetic lubricating oils which can be used. These are exemplified by the oils produced by polymerization of ethylene oxide or propylene oxide, alkyl and aryl ethers of these polyoxy-alkylene polymers (for example methyl polyisopropylene glycol ether with an average molecular weight of approx. 1000, dlphenyl ether of polyethylene glycol with a molecular weight of 500-1000, dlethyl ether of polypropylene glycol with a molecular weight of 1000-1500 and so on) or mono- and polycarboxylic esters thereof, for example acetic acid esters, mixed C 3 -C 8 fatty acid esters and C 1 -oxo acid diesters of tetraethylene glycol.

Other suitable classes of synthetic lubricating oils which may be used include the esters of dicarboxylic acids (for example, phthalic, succinic, alkyl succinic, alkenyl succinic, maleic, azelain, suberin, sebacin, fumaric, adipic, malonic, alkylmalonic -, alkenyl malonic acid or linoleic acid dimer) with a number of alcohols, for example butyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol and so on. Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of the linoleic acid dimer, the complex ester formed by reaction of one mole of sebacic acid with two moles of tetraethylene glycol and two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include those prepared from C 5 - to C 3 -monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol and so on.

Silicon-based oils such as polyalkyl, polyaryl, polyalkyloxy, or polyaryloxysiloxane oils and silicate oils constitute another useful class of synthetic lubricants (for example, tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate, tetra-(4-methyl -hexyl)silicate, tetra-(p-tert-butyl-phenyl)silicate, hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxane, poly(methylphenyl)siloxanes and so on). Other synthetic lubricating oils include liquid esters of phosphorous-containing acids, (for example, tricresyl phosphate, trioctyl phosphate, the diethyl ester of decanephosphonic acid, and so on), polymeric tetrahydrofurans, and the like.

Unrefined, refined or re-refined oils, either natural or synthetic (as well as mixtures of two or more of these) of the type described above can be used in the preparations according to the invention. Unreacted oils are those obtained directly from a natural or synthetic source without further purification. For example, a shale oil obtained directly from retorting, a petroleum oil obtained directly from a primary distillation or ester oil obtained from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to unrefined oils except that they are further processed in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art, for example solvent extraction, secondary distillation, acid or base extraction, filtration, percolation and so on. Re-refined oils are obtained by processes equivalent to those used to obtain refined oils, applied to refined oils that have already been in use. Such re-refined oils are also known as reprocessed or refreshed oils and are often further processed by techniques aimed at removing used additives or oil degradation products.

The preparations according to the invention will usually be used in the lubricant mixture according to the invention in an amount sufficient to provide the desired improvement in properties such as improved oxidation-corrosion inhibition, anti-wear and/or extreme pressure properties. More generally, this amount will be from 0.001 to 20% by weight of the particular oil in which they are used. The optimum amount used in a given lubricant is of course dependent on the further content of the particular lubricant mixture, the operating conditions and the particular additives used. In lubricant compositions operating under extremely adverse conditions such as marine diesel engine lubricant compositions, the formulations may be present in the lubricant in amounts up to 30% by weight or more of the total weight of the lubricant composition.

In a preferred embodiment, the lubricant oil mixture will comprise an oil with lubricity and the components (A) and

(B) as described above. The invention also aims at the use of other additives in the lubricant mixtures according to

the inventions. Such additives are those that are usually used in the lubricating oil, such as detergents, dispersing

agents, oxidation inhibiting agents, pour point reducing agents, extreme pressure agents, antiwear agents, color stabilizers and antifoam agents.

Further extreme pressure agents and corrosion and oxidation inhibiting agents which can be incorporated into the preparations according to the invention are exemplified by chlorinated aliphatic hydrocarbons such as chlorinated wax; organic sulfides and polysulfides such as benzyl disulfide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized methyl ester of olenic acid, sulfurized alkylphenol, sulfurized dipentene and sulfurized terpene. Group 11 metal phosphorodithioates can also be incorporated into some of the lubricants. Examples of useful metal phosphorodithioates include zinc dicyclohexyl phosphorodithioate, zinc dioctyl phosphorodithioate, barium di(heptylphenyl) phosphorodithioate, cadmium dinonyl phosphorodithioate and the zinc salt of a phosphorodithioate prepared by reacting phosphorus pentasulfide with an equimolar amount of isopropyl alcohol and a hexyl alcohol. When it is desired to formulate lubricating oils containing small amounts of phosphorus, such phosphorus dithioates should be avoided if possible.

Many of the above-mentioned additional extreme pressure agents and corrosion oxidation inhibitors also serve as antiwear agents. Zinc dialkyl phosphorodithioates are well known examples.

Pour point depressants a particularly useful type of additive that is often incorporated into the lubricating oils described. The use of such pour point depressants in oil based mixtures to improve the low pressure properties of oil based mixtures is well known in the art, see for example page 8 of "Lubricant Additives" of CV. Smalheer and R. Kennedy Smith (Lezius-Hiles Co. publishers, Cleveland, Ohio, 1967).

Examples of usable pour point depressants are polymethacrylates, polyacrylates, polyacrylamides, condensation products of halogenated paraffin waxes and aromatic compounds, vinyl carboxylate polymers and terpolymers of dialkyl fumarates, vinyl esters of fatty acids and alkyl vinyl ethers. Pour point depressors which can be used for the purposes of the invention, techniques for their manufacture as well as their use are described in US-PS 2,387,501; 2,015,748; 2,655,479; 1,815,022; 2,191,498; 2,666,746; 2,721,877; 2,721,878 and 3,250,715.

Antifoam agents are used to reduce or prevent the formation of stable foam. Typical antifoam agents include silicones or organic polymers. Additional antifoam compositions are described in "Foam Control Agents" by Henty T. Kerner (Noyes Data Corporation, 1976), 125-162.

Following are illustrative examples of preparations according to the invention (including additive concentrates and lubricants). All parts and percentages are by weight of the total mixture unless otherwise stated. Lubricating oil mixtures containing the preparations according to the invention as illustrated above show improved corrosion inhibition, anti-wear and extreme pressure properties. When the lubricating oil mixtures according to the invention contain a sulfurized Diels-Alder adduct with a sulfur:adduct molar ratio of less than 1:1, good nitrile sealing compatibility is achieved.

Claims (13)

1. Lubricant preparation comprising a major amount of an oil with lubricant viscosity and a minor amount of an oil-soluble preparation, characterized in that it comprises: (A) at least one metal salt of at least one dithiocarbamic acid of the formula wherein Ri and R2 are each independently hydrocarbyl groups or together form polymethylene or alkyl-substituted polymethylene groups where the total number of carbon atoms in Ri and R2 is sufficient to make the metal salt oil-soluble, and (B) at least one oil-soluble sulfurized Diels-Alder adduct of at least a dienophile with at least one aliphatic conjugated diene, the sulfurized adduct comprising the reaction product of sulfur and Diels-Alder adducts in a molar ratio of less than 1:1; where the weight ratio A:B lies within the range 1:10 to 50:1 and where further the lubricant preparation contains less than 0.1 weight-$ phosphorus. 2. Preparation according to claim 1, characterized in that Ri and R2 are each independently alkyl-, cycloalkyl-, aryl-, alkaryl or aralkyl groups. 3. Preparation according to claim 2, characterized in that Ri and R2 are alkyl groups containing at least two carbon atoms. 4. Preparation according to any one of the preceding claims, characterized in that the metal salt A is of a polyvalent metal. 5. Preparation according to any one of the preceding claims, characterized in that the dienophile comprises an α, 3-ethylenically unsaturated aliphatic carboxylic acid ester, carboxylic acid amide, halide, nitrile, aldehyde, ketone or a mixture thereof. 6. Preparation according to claim 5, characterized in that the dienophile contains at least one but not more than two C(0)ORg where Rg is the residue of a saturated aliphatic alcohol with up to 40 carbon atoms. 7. Preparation according to any one of the preceding claims, characterized in that the dienophile is an ester of acrylic or methacrylic acid. 8. Preparation according to any one of the preceding claims, characterized in that the aliphatic conjugated diene corresponds to the formula where R to R<5> are each independently selected from hydrogen, alkyl, halogen, alkoxy, alkenyl, alkenyloxy, carboxy, cyano, amino, alkylamino, dialkylamino, phenyl and phenyl substituted with 1 to 3 substituents corresponding to R to R<5> ; or R, R<2>, R<3> and R<*> are as indicated above and R<*> and R<4> are alkylene groups linked together to form a cyclic diene. 9. Preparation according to claim 8, characterized in that R2 and R<3> are hydrogen and R, R1, R<4> and R<5> are each independently hydrogen, halogen or lower alkyl. 10. Preparation according to any one of the preceding claims, characterized in that the diene is piperylene, isoprene, methylisoprene, chloroprene, 1,3-butadiene or mixtures thereof. 11. Preparation according to any one of the preceding claims, characterized in that the phosphorus is present as a phosphorus dithioate. 12. Preparation according to any one of the preceding claims, characterized in that it essentially does not contain phosphorus. 13. Process for the production of a lubricating oil preparation, characterized in that it comprises combining a larger amount of an oil with lubricant viscosity with a smaller amount of an oil-soluble preparation, comprising (A) at least one metal salt wherein R 1 and R 2 are each independently hydrocarbyl groups or together form polymethylene or alkyl-substituted polymethylene groups where the total number of carbon atoms in R 1 and R 2 is sufficient to make the metal salt oil-soluble, and (B) at least one oil-soluble sulfurized Diels-Alder adduct of at least one dienophile with at least one aliphatic conjugated diene, the sulfurized adduct comprising the reaction product of sulfur and Diels-Alder adducts in a molar ratio of less than 1:1; where the weight ratio A:B lies within the range 1:10 to 50:1 and where further the lubricant preparation contains less than 0.1 weight-$ phosphorus.